dom: Implement `WritableStream` (#34844)

* add basic interface for writable stream Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add stubs for pipeTo and pipeThrough methods Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add stubs for writable stream defautl writer Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add stubs for writable stream controller Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add underlying source dict Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add underlying source dict Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement constructor Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement init writable stream Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * impl setup default controller Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller setup Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller advance queue if neededd Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream finish erroring Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream reject close and closed promise if needed Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * finish implementation of stream finish erroring Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * call into controller setup from stream constructor Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream mark first write request in flight Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller process write Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * call into advance queue if needed at various points Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream deal with rejection, use from_safe_context Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller clear algorithms Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unused todo Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream start erroring Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * finish writer ensure ready promise rejected Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream finish in flight write request Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement write constructor and setup Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller error Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary unsafe code Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * finish implementing process write Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement close sentinel Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement public locked Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream abort Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix use of crown Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary options around writer promises Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer get desired size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer ready Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer abort Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer release lock Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer public write Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement private writer write Uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement writer release. Uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * impl controller process close Uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * finish controller process close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * root promise handlers Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * handler errors in stream and writer constructor finish implementation of stream finish in flight close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix warnings Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement controller get chunk size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * tidy the webidls Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * implement stream get writer Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix assertion of stream state when advancing queue if needed Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add docs for value with size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * use reject_error in abort Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary allowances of unsafe code Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * turn writable-streams test suite on Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update encodings test expectations Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * properly check if type is set on sink in stream constructor Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix double borrow in controller advance queue if needed Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * make the queue aware of the close sentinel when dequeuing a value Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix assertion of no backpressure in update backpressure Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * also clear strategy size when clearing algorithms Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove this object arg when calling into strategy size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix has operations marked in flight Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix typo in has in flight write request Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * turn error into no-op when aborting a stream, if the stream is closed or errored. Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix error handling of calling into abort algorithm Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix error handling of calling into close and write algorithms Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix double borrow on queue fix logic in update_backpressure fix logic in get_desired_size fix logic in writer setup Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update test expectations for aborting suite Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix controller get_backpressure Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix clippy Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update test expectations to expect errors in tests using unsupported apis Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix error handling of calling into start algo in controller setup Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update test expectations for test checking for undefined this in strategy size call Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update test expectation to timeout for response-stream-with-broken-then.any.worker Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * update interfaces Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix use of global() and error to_jsval Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix use of crown for promise handlers Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove fail expectation from worker interface objects test Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove fail expectation for test expecting this to be undefined in callback Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix documentation link for writablestream state Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * refactor write_requests to use a vec deque uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary doc Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * refactor reject_close_and_closed_promise_if_needed to take a safe js context as argument uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * pass globals and contexts by ref where possible uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix doc link for controller Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary comment Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * change update_backpressure to be a method of the writablestream uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * rename writer method that resolve closed and ready promise for clarity uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * add comments for steps in peek queue value Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix doc link for the abort algorihtm fulfillment handler Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix step doc and variable name in abort algo rejection handler Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * Add must_root to pending abort request Co-authored-by: Josh Matthews <josh@joshmatthews.net> Signed-off-by: Gregory Terzian <2792687+gterzian@users.noreply.github.com> * limit visibility to crate for has_operations_marked_inflight Co-authored-by: Josh Matthews <josh@joshmatthews.net> Signed-off-by: Gregory Terzian <2792687+gterzian@users.noreply.github.com> * limit visibility to crate for get_stored_error Co-authored-by: Josh Matthews <josh@joshmatthews.net> Signed-off-by: Gregory Terzian <2792687+gterzian@users.noreply.github.com> * remove potention re-borrow risk in reject loop on write requests in finish_erroring Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove potential re-borrow risk when taking pending abort request in finish_erroring Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove potential re-borrow risk when taking close request in reject_close_and_closed_promise_if_needed Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove re-borrow risks in finish_in_flight_close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove re-borrow risk on in_flight_close_request in finish_in_flight_close_with_error Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary clone of of reason in abort Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix condition on backpressure and a writable state in close Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * limit visibility to crate for update_backpressure Co-authored-by: Josh Matthews <josh@joshmatthews.net> Signed-off-by: Gregory Terzian <2792687+gterzian@users.noreply.github.com> * remove mutability of reason in abort workflow Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove unnecessary use of ignore_malloc_size_of around Dom in controller Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix ignore malloc size of comment for strategy size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * reduce visibility of public methods to crate in controller Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * remove use of JS_GetPendingException in controller get_chunk_size Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * return early on error in write Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * use is_some_and in assertion that stream.witer is writer in release Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * root pending abort request uses ai Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> * fix mutable re-borrow risk in writer Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> --------- Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com> Signed-off-by: Gregory Terzian <2792687+gterzian@users.noreply.github.com> Co-authored-by: Josh Matthews <josh@joshmatthews.net>
author: Gregory Terzian <2792687+gterzian@users.noreply.github.com> 2025-02-19 20:02:14 +0700
committer: GitHub <noreply@github.com> 2025-02-19 13:02:14 +0000
commit: df6d6361688f487142809b5923e030447870e073 (patch)
tree: 3e81927a47cfc98e8c895c8153eee47ee5758753 /components/script/dom
parent: 720bc725b0c1cd5f01f9ff1d17793a3b1f32a480 (diff)
download: servo-df6d6361688f487142809b5923e030447870e073.tar.gz
servo-df6d6361688f487142809b5923e030447870e073.zip
5 files changed, 2350 insertions, 11 deletions
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 7127828224e..73320e527b4 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -628,6 +628,9 @@ pub(crate) mod workerlocation;
 pub(crate) mod workernavigator;
 pub(crate) mod worklet;
 pub(crate) mod workletglobalscope;
+pub(crate) mod writablestream;
+pub(crate) mod writablestreamdefaultcontroller;
+pub(crate) mod writablestreamdefaultwriter;
 pub(crate) mod xmldocument;
 pub(crate) mod xmlhttprequest;
 pub(crate) mod xmlhttprequesteventtarget;
diff --git a/components/script/dom/readablestreamdefaultcontroller.rs b/components/script/dom/readablestreamdefaultcontroller.rs
index 6aa17253282..779bf1947ba 100644
--- a/components/script/dom/readablestreamdefaultcontroller.rs
+++ b/components/script/dom/readablestreamdefaultcontroller.rs
@@ -115,21 +115,25 @@ impl Callback for StartAlgorithmRejectionHandler {
 }
 
 /// <https://streams.spec.whatwg.org/#value-with-size>
-#[derive(JSTraceable)]
+#[derive(Debug, JSTraceable, PartialEq)]
 #[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
 pub(crate) struct ValueWithSize {
-    value: Box<Heap<JSVal>>,
-    size: f64,
+    /// <https://streams.spec.whatwg.org/#value-with-size-value>
+    pub(crate) value: Box<Heap<JSVal>>,
+    /// <https://streams.spec.whatwg.org/#value-with-size-size>
+    pub(crate) size: f64,
 }
 
 /// <https://streams.spec.whatwg.org/#value-with-size>
-#[derive(JSTraceable)]
+#[derive(Debug, JSTraceable, PartialEq)]
 #[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
 pub(crate) enum EnqueuedValue {
     /// A value enqueued from Rust.
     Native(Box<[u8]>),
     /// A Js value.
     Js(ValueWithSize),
+    /// <https://streams.spec.whatwg.org/#close-sentinel>
+    CloseSentinel,
 }
 
 impl EnqueuedValue {
@@ -137,6 +141,9 @@ impl EnqueuedValue {
         match self {
             EnqueuedValue::Native(v) => v.len() as f64,
             EnqueuedValue::Js(v) => v.size,
+            // The size of the sentinel is zero,
+            // as per <https://streams.spec.whatwg.org/#ref-for-close-sentinel%E2%91%A0>
+            EnqueuedValue::CloseSentinel => 0.,
         }
     }
 
@@ -152,6 +159,9 @@ impl EnqueuedValue {
             EnqueuedValue::Js(value_with_size) => unsafe {
                 value_with_size.value.to_jsval(*cx, rval);
             },
+            EnqueuedValue::CloseSentinel => {
+                unreachable!("The close sentinel is never made available as a js val.")
+            },
         }
     }
 }
@@ -161,6 +171,7 @@ fn is_non_negative_number(value: &EnqueuedValue) -> bool {
     let value_with_size = match value {
         EnqueuedValue::Native(_) => return true,
         EnqueuedValue::Js(value_with_size) => value_with_size,
+        EnqueuedValue::CloseSentinel => return true,
     };
 
     // If v is not a Number, return false.
@@ -186,23 +197,29 @@ pub(crate) struct QueueWithSizes {
     #[ignore_malloc_size_of = "EnqueuedValue::Js"]
     queue: VecDeque<EnqueuedValue>,
     /// <https://streams.spec.whatwg.org/#readablestreamdefaultcontroller-queuetotalsize>
-    total_size: f64,
+    pub(crate) total_size: f64,
 }
 
 impl QueueWithSizes {
     /// <https://streams.spec.whatwg.org/#dequeue-value>
-    fn dequeue_value(&mut self, cx: SafeJSContext, rval: MutableHandleValue) {
+    /// A none `rval` means we're dequeing the close sentinel,
+    /// which should never be made available to script.
+    pub(crate) fn dequeue_value(&mut self, cx: SafeJSContext, rval: Option<MutableHandleValue>) {
         let Some(value) = self.queue.front() else {
             unreachable!("Buffer cannot be empty when dequeue value is called into.");
         };
         self.total_size -= value.size();
-        value.to_jsval(cx, rval);
+        if let Some(rval) = rval {
+            value.to_jsval(cx, rval);
+        } else {
+            assert_eq!(value, &EnqueuedValue::CloseSentinel);
+        }
         self.queue.pop_front();
     }
 
     /// <https://streams.spec.whatwg.org/#enqueue-value-with-size>
     #[cfg_attr(crown, allow(crown::unrooted_must_root))]
-    fn enqueue_value_with_size(&mut self, value: EnqueuedValue) -> Result<(), Error> {
+    pub(crate) fn enqueue_value_with_size(&mut self, value: EnqueuedValue) -> Result<(), Error> {
         // If ! IsNonNegativeNumber(size) is false, throw a RangeError exception.
         if !is_non_negative_number(&value) {
             return Err(Error::Range(
@@ -223,10 +240,30 @@ impl QueueWithSizes {
         Ok(())
     }
 
-    fn is_empty(&self) -> bool {
+    pub(crate) fn is_empty(&self) -> bool {
         self.queue.is_empty()
     }
 
+    /// <https://streams.spec.whatwg.org/#peek-queue-value>
+    /// Returns whether value is the close sentinel.
+    pub(crate) fn peek_queue_value(&self, cx: SafeJSContext, rval: MutableHandleValue) -> bool {
+        // Assert: container has [[queue]] and [[queueTotalSize]] internal slots.
+        // Done with the QueueWithSizes type.
+
+        // Assert: container.[[queue]] is not empty.
+        assert!(!self.is_empty());
+
+        // Let valueWithSize be container.[[queue]][0].
+        let value_with_size = self.queue.front().expect("Queue is not empty.");
+        if let EnqueuedValue::CloseSentinel = value_with_size {
+            return true;
+        }
+
+        // Return valueWithSize’s value.
+        value_with_size.to_jsval(cx, rval);
+        false
+    }
+
     /// Only used with native sources.
     fn get_in_memory_bytes(&self) -> Option<Vec<u8>> {
         self.queue
@@ -244,7 +281,7 @@ impl QueueWithSizes {
     }
 
     /// <https://streams.spec.whatwg.org/#reset-queue>
-    fn reset(&mut self) {
+    pub(crate) fn reset(&mut self) {
         self.queue.clear();
         self.total_size = Default::default();
     }
@@ -409,7 +446,7 @@ impl ReadableStreamDefaultController {
     /// <https://streams.spec.whatwg.org/#dequeue-value>
     fn dequeue_value(&self, cx: SafeJSContext, rval: MutableHandleValue) {
         let mut queue = self.queue.borrow_mut();
-        queue.dequeue_value(cx, rval);
+        queue.dequeue_value(cx, Some(rval));
     }
 
     /// <https://streams.spec.whatwg.org/#readable-stream-default-controller-should-call-pull>
diff --git a/components/script/dom/writablestream.rs b/components/script/dom/writablestream.rs
new file mode 100644
index 00000000000..e650db4a0ce
--- /dev/null
+++ b/components/script/dom/writablestream.rs
@@ -0,0 +1,970 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::cell::Cell;
+use std::collections::VecDeque;
+use std::mem;
+use std::ptr::{self};
+use std::rc::Rc;
+
+use dom_struct::dom_struct;
+use js::jsapi::{Heap, JSObject};
+use js::jsval::{JSVal, ObjectValue, UndefinedValue};
+use js::rust::{
+    HandleObject as SafeHandleObject, HandleValue as SafeHandleValue,
+    MutableHandleValue as SafeMutableHandleValue,
+};
+
+use crate::dom::bindings::cell::DomRefCell;
+use crate::dom::bindings::codegen::Bindings::QueuingStrategyBinding::QueuingStrategy;
+use crate::dom::bindings::codegen::Bindings::UnderlyingSinkBinding::UnderlyingSink;
+use crate::dom::bindings::codegen::Bindings::WritableStreamBinding::WritableStreamMethods;
+use crate::dom::bindings::conversions::ConversionResult;
+use crate::dom::bindings::error::Error;
+use crate::dom::bindings::import::module::Fallible;
+use crate::dom::bindings::reflector::{reflect_dom_object_with_proto, Reflector};
+use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
+use crate::dom::countqueuingstrategy::{extract_high_water_mark, extract_size_algorithm};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use crate::dom::promisenativehandler::{Callback, PromiseNativeHandler};
+use crate::dom::writablestreamdefaultcontroller::WritableStreamDefaultController;
+use crate::dom::writablestreamdefaultwriter::WritableStreamDefaultWriter;
+use crate::realms::{enter_realm, InRealm};
+use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
+
+impl js::gc::Rootable for AbortAlgorithmFulfillmentHandler {}
+
+/// The fulfillment handler for the abort steps of
+/// <https://streams.spec.whatwg.org/#writable-stream-finish-erroring>
+#[derive(JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct AbortAlgorithmFulfillmentHandler {
+    stream: Dom<WritableStream>,
+    #[ignore_malloc_size_of = "Rc is hard"]
+    abort_request_promise: Rc<Promise>,
+}
+
+impl Callback for AbortAlgorithmFulfillmentHandler {
+    fn callback(&self, cx: SafeJSContext, _v: SafeHandleValue, _realm: InRealm, _can_gc: CanGc) {
+        // Resolve abortRequest’s promise with undefined.
+        self.abort_request_promise.resolve_native(&());
+
+        // Perform ! WritableStreamRejectCloseAndClosedPromiseIfNeeded(stream).
+        self.stream
+            .as_rooted()
+            .reject_close_and_closed_promise_if_needed(cx);
+    }
+}
+
+impl js::gc::Rootable for AbortAlgorithmRejectionHandler {}
+
+/// The rejection handler for the abort steps of
+/// <https://streams.spec.whatwg.org/#writable-stream-finish-erroring>
+#[derive(JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct AbortAlgorithmRejectionHandler {
+    stream: Dom<WritableStream>,
+    #[ignore_malloc_size_of = "Rc is hard"]
+    abort_request_promise: Rc<Promise>,
+}
+
+impl Callback for AbortAlgorithmRejectionHandler {
+    fn callback(
+        &self,
+        cx: SafeJSContext,
+        reason: SafeHandleValue,
+        _realm: InRealm,
+        _can_gc: CanGc,
+    ) {
+        // Reject abortRequest’s promise with reason.
+        self.abort_request_promise.reject_native(&reason);
+
+        // Perform ! WritableStreamRejectCloseAndClosedPromiseIfNeeded(stream).
+        self.stream
+            .as_rooted()
+            .reject_close_and_closed_promise_if_needed(cx);
+    }
+}
+
+impl js::gc::Rootable for PendingAbortRequest {}
+
+/// <https://streams.spec.whatwg.org/#pending-abort-request>
+#[derive(JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct PendingAbortRequest {
+    /// <https://streams.spec.whatwg.org/#pending-abort-request-promise>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    promise: Rc<Promise>,
+
+    /// <https://streams.spec.whatwg.org/#pending-abort-request-reason>
+    #[ignore_malloc_size_of = "mozjs"]
+    reason: Box<Heap<JSVal>>,
+
+    /// <https://streams.spec.whatwg.org/#pending-abort-request-was-already-erroring>
+    was_already_erroring: bool,
+}
+
+/// <https://streams.spec.whatwg.org/#writablestream-state>
+#[derive(Clone, Copy, Debug, Default, JSTraceable, MallocSizeOf)]
+pub(crate) enum WritableStreamState {
+    #[default]
+    Writable,
+    Closed,
+    Erroring,
+    Errored,
+}
+
+/// <https://streams.spec.whatwg.org/#ws-class>
+#[dom_struct]
+pub struct WritableStream {
+    reflector_: Reflector,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-backpressure>
+    backpressure: Cell<bool>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-closerequest>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    close_request: DomRefCell<Option<Rc<Promise>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-controller>
+    controller: MutNullableDom<WritableStreamDefaultController>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-detached>
+    detached: Cell<bool>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-inflightwriterequest>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    in_flight_write_request: DomRefCell<Option<Rc<Promise>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-inflightcloserequest>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    in_flight_close_request: DomRefCell<Option<Rc<Promise>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-pendingabortrequest>
+    pending_abort_request: DomRefCell<Option<PendingAbortRequest>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-state>
+    state: Cell<WritableStreamState>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-storederror>
+    #[ignore_malloc_size_of = "mozjs"]
+    stored_error: Heap<JSVal>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-writer>
+    writer: MutNullableDom<WritableStreamDefaultWriter>,
+
+    /// <https://streams.spec.whatwg.org/#writablestream-writerequests>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    write_requests: DomRefCell<VecDeque<Rc<Promise>>>,
+}
+
+impl WritableStream {
+    #[cfg_attr(crown, allow(crown::unrooted_must_root))]
+    /// <https://streams.spec.whatwg.org/#initialize-readable-stream>
+    fn new_inherited() -> WritableStream {
+        WritableStream {
+            reflector_: Reflector::new(),
+            backpressure: Default::default(),
+            close_request: Default::default(),
+            controller: Default::default(),
+            detached: Default::default(),
+            in_flight_write_request: Default::default(),
+            in_flight_close_request: Default::default(),
+            pending_abort_request: Default::default(),
+            state: Default::default(),
+            stored_error: Default::default(),
+            writer: Default::default(),
+            write_requests: Default::default(),
+        }
+    }
+
+    fn new_with_proto(
+        global: &GlobalScope,
+        proto: Option<SafeHandleObject>,
+        can_gc: CanGc,
+    ) -> DomRoot<WritableStream> {
+        reflect_dom_object_with_proto(
+            Box::new(WritableStream::new_inherited()),
+            global,
+            proto,
+            can_gc,
+        )
+    }
+
+    /// Used as part of
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+    pub(crate) fn assert_no_controller(&self) {
+        assert!(self.controller.get().is_none());
+    }
+
+    /// Used as part of
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+    pub(crate) fn set_default_controller(&self, controller: &WritableStreamDefaultController) {
+        self.controller.set(Some(controller));
+    }
+
+    pub(crate) fn is_writable(&self) -> bool {
+        matches!(self.state.get(), WritableStreamState::Writable)
+    }
+
+    pub(crate) fn is_erroring(&self) -> bool {
+        matches!(self.state.get(), WritableStreamState::Erroring)
+    }
+
+    pub(crate) fn is_errored(&self) -> bool {
+        matches!(self.state.get(), WritableStreamState::Errored)
+    }
+
+    pub(crate) fn is_closed(&self) -> bool {
+        matches!(self.state.get(), WritableStreamState::Closed)
+    }
+
+    pub(crate) fn has_in_flight_write_request(&self) -> bool {
+        self.in_flight_write_request.borrow().is_some()
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-has-operation-marked-in-flight>
+    pub(crate) fn has_operations_marked_inflight(&self) -> bool {
+        let in_flight_write_requested = self.in_flight_write_request.borrow().is_some();
+        let in_flight_close_requested = self.in_flight_close_request.borrow().is_some();
+
+        in_flight_write_requested || in_flight_close_requested
+    }
+
+    /// <https://streams.spec.whatwg.org/#writablestream-storederror>
+    pub(crate) fn get_stored_error(&self, mut handle_mut: SafeMutableHandleValue) {
+        handle_mut.set(self.stored_error.get());
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-finish-erroring>
+    pub(crate) fn finish_erroring(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) {
+        // Assert: stream.[[state]] is "erroring".
+        assert!(self.is_erroring());
+
+        // Assert: ! WritableStreamHasOperationMarkedInFlight(stream) is false.
+        assert!(!self.has_operations_marked_inflight());
+
+        // Set stream.[[state]] to "errored".
+        self.state.set(WritableStreamState::Errored);
+
+        // Perform ! stream.[[controller]].[[ErrorSteps]]().
+        let Some(controller) = self.controller.get() else {
+            unreachable!("Stream should have a controller.");
+        };
+        controller.perform_error_steps();
+
+        // Let storedError be stream.[[storedError]].
+        rooted!(in(*cx) let mut stored_error = UndefinedValue());
+        self.get_stored_error(stored_error.handle_mut());
+
+        // For each writeRequest of stream.[[writeRequests]]:
+        let write_requests = mem::take(&mut *self.write_requests.borrow_mut());
+        for request in write_requests {
+            // Reject writeRequest with storedError.
+            request.reject(cx, stored_error.handle());
+        }
+
+        // Set stream.[[writeRequests]] to an empty list.
+        // Done above with `drain`.
+
+        // If stream.[[pendingAbortRequest]] is undefined,
+        if self.pending_abort_request.borrow().is_none() {
+            // Perform ! WritableStreamRejectCloseAndClosedPromiseIfNeeded(stream).
+            self.reject_close_and_closed_promise_if_needed(cx);
+
+            // Return.
+            return;
+        }
+
+        // Let abortRequest be stream.[[pendingAbortRequest]].
+        // Set stream.[[pendingAbortRequest]] to undefined.
+        rooted!(in(*cx) let pending_abort_request = self.pending_abort_request.borrow_mut().take());
+        if let Some(pending_abort_request) = &*pending_abort_request {
+            // If abortRequest’s was already erroring is true,
+            if pending_abort_request.was_already_erroring {
+                // Reject abortRequest’s promise with storedError.
+                pending_abort_request
+                    .promise
+                    .reject(cx, stored_error.handle());
+
+                // Perform ! WritableStreamRejectCloseAndClosedPromiseIfNeeded(stream).
+                self.reject_close_and_closed_promise_if_needed(cx);
+
+                // Return.
+                return;
+            }
+
+            // Let promise be ! stream.[[controller]].[[AbortSteps]](abortRequest’s reason).
+            rooted!(in(*cx) let mut reason = UndefinedValue());
+            reason.set(pending_abort_request.reason.get());
+            let promise = controller.abort_steps(cx, global, reason.handle(), can_gc);
+
+            // Upon fulfillment of promise,
+            rooted!(in(*cx) let mut fulfillment_handler = Some(AbortAlgorithmFulfillmentHandler {
+                stream: Dom::from_ref(self),
+                abort_request_promise: pending_abort_request.promise.clone(),
+            }));
+
+            // Upon rejection of promise with reason r,
+            rooted!(in(*cx) let mut rejection_handler = Some(AbortAlgorithmRejectionHandler {
+                stream: Dom::from_ref(self),
+                abort_request_promise: pending_abort_request.promise.clone(),
+            }));
+
+            let handler = PromiseNativeHandler::new(
+                global,
+                fulfillment_handler.take().map(|h| Box::new(h) as Box<_>),
+                rejection_handler.take().map(|h| Box::new(h) as Box<_>),
+            );
+            let realm = enter_realm(global);
+            let comp = InRealm::Entered(&realm);
+            promise.append_native_handler(&handler, comp, can_gc);
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-reject-close-and-closed-promise-if-needed>
+    fn reject_close_and_closed_promise_if_needed(&self, cx: SafeJSContext) {
+        // Assert: stream.[[state]] is "errored".
+        assert!(self.is_errored());
+
+        rooted!(in(*cx) let mut stored_error = UndefinedValue());
+        self.get_stored_error(stored_error.handle_mut());
+
+        // If stream.[[closeRequest]] is not undefined
+        let close_request = self.close_request.borrow_mut().take();
+        if let Some(close_request) = close_request {
+            // Assert: stream.[[inFlightCloseRequest]] is undefined.
+            assert!(self.in_flight_close_request.borrow().is_none());
+
+            // Reject stream.[[closeRequest]] with stream.[[storedError]].
+            close_request.reject_native(&stored_error.handle())
+
+            // Set stream.[[closeRequest]] to undefined.
+            // Done with `take` above.
+        }
+
+        // Let writer be stream.[[writer]].
+        // If writer is not undefined,
+        if let Some(writer) = self.writer.get() {
+            // Reject writer.[[closedPromise]] with stream.[[storedError]].
+            writer.reject_closed_promise_with_stored_error(&stored_error.handle());
+
+            // Set writer.[[closedPromise]].[[PromiseIsHandled]] to true.
+            writer.set_close_promise_is_handled();
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-close-queued-or-in-flight>
+    pub(crate) fn close_queued_or_in_flight(&self) -> bool {
+        let close_requested = self.close_request.borrow().is_some();
+        let in_flight_close_requested = self.in_flight_close_request.borrow().is_some();
+
+        close_requested || in_flight_close_requested
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-finish-in-flight-write>
+    pub(crate) fn finish_in_flight_write(&self) {
+        let Some(in_flight_write_request) = self.in_flight_write_request.borrow_mut().take() else {
+            // Assert: stream.[[inFlightWriteRequest]] is not undefined.
+            unreachable!("Stream should have a write request");
+        };
+
+        // Resolve stream.[[inFlightWriteRequest]] with undefined.
+        in_flight_write_request.resolve_native(&());
+
+        // Set stream.[[inFlightWriteRequest]] to undefined.
+        // Done above with `take`.
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-start-erroring>
+    pub(crate) fn start_erroring(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        // Assert: stream.[[storedError]] is undefined.
+        assert!(self.stored_error.get().is_undefined());
+
+        // Assert: stream.[[state]] is "writable".
+        assert!(self.is_writable());
+
+        // Let controller be stream.[[controller]].
+        let Some(controller) = self.controller.get() else {
+            // Assert: controller is not undefined.
+            unreachable!("Stream should have a controller.");
+        };
+
+        // Set stream.[[state]] to "erroring".
+        self.state.set(WritableStreamState::Erroring);
+
+        // Set stream.[[storedError]] to reason.
+        self.stored_error.set(*error);
+
+        // Let writer be stream.[[writer]].
+        if let Some(writer) = self.writer.get() {
+            // If writer is not undefined, perform ! WritableStreamDefaultWriterEnsureReadyPromiseRejected
+            writer.ensure_ready_promise_rejected(global, error, can_gc);
+        }
+
+        // If ! WritableStreamHasOperationMarkedInFlight(stream) is false and controller.[[started]] is true
+        if !self.has_operations_marked_inflight() && controller.started() {
+            // perform ! WritableStreamFinishErroring
+            self.finish_erroring(cx, global, can_gc);
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-deal-with-rejection>
+    pub(crate) fn deal_with_rejection(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        // Let state be stream.[[state]].
+
+        // If state is "writable",
+        if self.is_writable() {
+            // Perform ! WritableStreamStartErroring(stream, error).
+            self.start_erroring(cx, global, error, can_gc);
+
+            // Return.
+            return;
+        }
+
+        // Assert: state is "erroring".
+        assert!(self.is_erroring());
+
+        // Perform ! WritableStreamFinishErroring(stream).
+        self.finish_erroring(cx, global, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-mark-first-write-request-in-flight>
+    pub(crate) fn mark_first_write_request_in_flight(&self) {
+        let mut in_flight_write_request = self.in_flight_write_request.borrow_mut();
+        let mut write_requests = self.write_requests.borrow_mut();
+
+        // Assert: stream.[[inFlightWriteRequest]] is undefined.
+        assert!(in_flight_write_request.is_none());
+
+        // Assert: stream.[[writeRequests]] is not empty.
+        assert!(!write_requests.is_empty());
+
+        // Let writeRequest be stream.[[writeRequests]][0].
+        // Remove writeRequest from stream.[[writeRequests]].
+        let write_request = write_requests.pop_front().unwrap();
+
+        // Set stream.[[inFlightWriteRequest]] to writeRequest.
+        *in_flight_write_request = Some(write_request);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-mark-close-request-in-flight>
+    pub(crate) fn mark_close_request_in_flight(&self) {
+        let mut in_flight_close_request = self.in_flight_close_request.borrow_mut();
+        let mut close_request = self.close_request.borrow_mut();
+
+        // Assert: stream.[[inFlightCloseRequest]] is undefined.
+        assert!(in_flight_close_request.is_none());
+
+        // Assert: stream.[[closeRequest]] is not undefined.
+        assert!(close_request.is_some());
+
+        // Let closeRequest be stream.[[closeRequest]].
+        // Set stream.[[closeRequest]] to undefined.
+        let close_request = close_request.take().unwrap();
+
+        // Set stream.[[inFlightCloseRequest]] to closeRequest.
+        *in_flight_close_request = Some(close_request);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-finish-in-flight-close>
+    pub(crate) fn finish_in_flight_close(&self, cx: SafeJSContext) {
+        let Some(in_flight_close_request) = self.in_flight_close_request.borrow_mut().take() else {
+            // Assert: stream.[[inFlightCloseRequest]] is not undefined.
+            unreachable!("in_flight_close_request must be Some");
+        };
+
+        // Resolve stream.[[inFlightCloseRequest]] with undefined.
+        in_flight_close_request.resolve_native(&());
+
+        // Set stream.[[inFlightCloseRequest]] to undefined.
+        // Done with take above.
+
+        // Assert: stream.[[state]] is "writable" or "erroring".
+        assert!(self.is_writable() || self.is_erroring());
+
+        // If state is "erroring",
+        if self.is_erroring() {
+            // Set stream.[[storedError]] to undefined.
+            self.stored_error.set(UndefinedValue());
+
+            // If stream.[[pendingAbortRequest]] is not undefined,
+            rooted!(in(*cx) let pending_abort_request = self.pending_abort_request.borrow_mut().take());
+            if let Some(pending_abort_request) = &*pending_abort_request {
+                // Resolve stream.[[pendingAbortRequest]]'s promise with undefined.
+                pending_abort_request.promise.resolve_native(&());
+
+                // Set stream.[[pendingAbortRequest]] to undefined.
+                // Done above with `take`.
+            }
+        }
+
+        // Set stream.[[state]] to "closed".
+        self.state.set(WritableStreamState::Closed);
+
+        // Let writer be stream.[[writer]].
+        if let Some(writer) = self.writer.get() {
+            // If writer is not undefined,
+            // resolve writer.[[closedPromise]] with undefined.
+            writer.resolve_closed_promise_with_undefined();
+        }
+
+        // Assert: stream.[[pendingAbortRequest]] is undefined.
+        assert!(self.pending_abort_request.borrow().is_none());
+
+        // Assert: stream.[[storedError]] is undefined.
+        assert!(self.stored_error.get().is_undefined());
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-finish-in-flight-close-with-error>
+    pub(crate) fn finish_in_flight_close_with_error(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        let Some(in_flight_close_request) = self.in_flight_close_request.borrow_mut().take() else {
+            // Assert: stream.[[inFlightCloseRequest]] is not undefined.
+            unreachable!("Inflight close request must be defined.");
+        };
+
+        // Reject stream.[[inFlightCloseRequest]] with error.
+        in_flight_close_request.reject_native(&error);
+
+        // Set stream.[[inFlightCloseRequest]] to undefined.
+        // Done above with `take`.
+
+        // Assert: stream.[[state]] is "writable" or "erroring".
+        assert!(self.is_erroring() || self.is_writable());
+
+        // If stream.[[pendingAbortRequest]] is not undefined,
+        rooted!(in(*cx) let pending_abort_request = self.pending_abort_request.borrow_mut().take());
+        if let Some(pending_abort_request) = &*pending_abort_request {
+            // Reject stream.[[pendingAbortRequest]]'s promise with error.
+            pending_abort_request.promise.reject_native(&error);
+
+            // Set stream.[[pendingAbortRequest]] to undefined.
+            // Done above with `take`.
+        }
+
+        // Perform ! WritableStreamDealWithRejection(stream, error).
+        self.deal_with_rejection(cx, global, error, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-finish-in-flight-write-with-error>
+    pub(crate) fn finish_in_flight_write_with_error(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        let Some(in_flight_write_request) = self.in_flight_write_request.borrow_mut().take() else {
+            // Assert: stream.[[inFlightWriteRequest]] is not undefined.
+            unreachable!("Inflight write request must be defined.");
+        };
+
+        // Reject stream.[[inFlightWriteRequest]] with error.
+        in_flight_write_request.reject_native(&error);
+
+        // Set stream.[[inFlightWriteRequest]] to undefined.
+        // Done above with `take`.
+
+        // Assert: stream.[[state]] is "writable" or "erroring".
+        assert!(self.is_erroring() || self.is_writable());
+
+        // Perform ! WritableStreamDealWithRejection(stream, error).
+        self.deal_with_rejection(cx, global, error, can_gc);
+    }
+
+    pub(crate) fn get_writer(&self) -> Option<DomRoot<WritableStreamDefaultWriter>> {
+        self.writer.get()
+    }
+
+    pub(crate) fn set_writer(&self, writer: Option<&WritableStreamDefaultWriter>) {
+        self.writer.set(writer);
+    }
+
+    pub(crate) fn set_backpressure(&self, backpressure: bool) {
+        self.backpressure.set(backpressure);
+    }
+
+    pub(crate) fn get_backpressure(&self) -> bool {
+        self.backpressure.get()
+    }
+
+    /// <https://streams.spec.whatwg.org/#is-writable-stream-locked>
+    pub(crate) fn is_locked(&self) -> bool {
+        // If stream.[[writer]] is undefined, return false.
+        // Return true.
+        self.get_writer().is_some()
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-add-write-request>
+    pub(crate) fn add_write_request(&self, global: &GlobalScope, can_gc: CanGc) -> Rc<Promise> {
+        // Assert: ! IsWritableStreamLocked(stream) is true.
+        assert!(self.is_locked());
+
+        // Assert: stream.[[state]] is "writable".
+        assert!(self.is_writable());
+
+        // Let promise be a new promise.
+        let promise = Promise::new(global, can_gc);
+
+        // Append promise to stream.[[writeRequests]].
+        self.write_requests.borrow_mut().push_back(promise.clone());
+
+        // Return promise.
+        promise
+    }
+
+    // Returns the rooted controller of the stream, if any.
+    pub(crate) fn get_controller(&self) -> Option<DomRoot<WritableStreamDefaultController>> {
+        self.controller.get()
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-abort>
+    pub(crate) fn abort(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        provided_reason: SafeHandleValue,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        // If stream.[[state]] is "closed" or "errored",
+        if self.is_closed() || self.is_errored() {
+            // return a promise resolved with undefined.
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&());
+            return promise;
+        }
+
+        // TODO: Signal abort on stream.[[controller]].[[abortController]] with reason.
+
+        // TODO: If state is "closed" or "errored", return a promise resolved with undefined.
+        // Note: state may have changed because of signal above.
+
+        // If stream.[[pendingAbortRequest]] is not undefined,
+        if self.pending_abort_request.borrow().is_some() {
+            // return stream.[[pendingAbortRequest]]'s promise.
+            return self
+                .pending_abort_request
+                .borrow()
+                .as_ref()
+                .expect("Pending abort request must be Some.")
+                .promise
+                .clone();
+        }
+
+        // Assert: state is "writable" or "erroring".
+        assert!(self.is_writable() || self.is_erroring());
+
+        // Let wasAlreadyErroring be false.
+        let mut was_already_erroring = false;
+        rooted!(in(*cx) let undefined_reason = UndefinedValue());
+
+        // If state is "erroring",
+        let reason = if self.is_erroring() {
+            // Set wasAlreadyErroring to true.
+            was_already_erroring = true;
+
+            // Set reason to undefined.
+            undefined_reason.handle()
+        } else {
+            // Use the provided reason.
+            provided_reason
+        };
+
+        // Let promise be a new promise.
+        let promise = Promise::new(global, can_gc);
+
+        // Set stream.[[pendingAbortRequest]] to a new pending abort request
+        // whose promise is promise,
+        // reason is reason,
+        // and was already erroring is wasAlreadyErroring.
+        *self.pending_abort_request.borrow_mut() = Some(PendingAbortRequest {
+            promise: promise.clone(),
+            reason: Heap::boxed(reason.get()),
+            was_already_erroring,
+        });
+
+        // If wasAlreadyErroring is false,
+        if !was_already_erroring {
+            // perform ! WritableStreamStartErroring(stream, reason)
+            self.start_erroring(cx, global, reason, can_gc);
+        }
+
+        // Return promise.
+        promise
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-close>
+    pub(crate) fn close(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        // Let state be stream.[[state]].
+        // If state is "closed" or "errored",
+        if self.is_closed() || self.is_errored() {
+            // return a promise rejected with a TypeError exception.
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(Error::Type("Stream is closed or errored.".to_string()));
+            return promise;
+        }
+
+        // Assert: state is "writable" or "erroring".
+        assert!(self.is_writable() || self.is_erroring());
+
+        // Assert: ! WritableStreamCloseQueuedOrInFlight(stream) is false.
+        assert!(!self.close_queued_or_in_flight());
+
+        // Let promise be a new promise.
+        let promise = Promise::new(global, can_gc);
+
+        // Set stream.[[closeRequest]] to promise.
+        *self.close_request.borrow_mut() = Some(promise.clone());
+
+        // Let writer be stream.[[writer]].
+        // If writer is not undefined,
+        if let Some(writer) = self.writer.get() {
+            // and stream.[[backpressure]] is true,
+            // and state is "writable",
+            if self.get_backpressure() && self.is_writable() {
+                // resolve writer.[[readyPromise]] with undefined.
+                writer.resolve_ready_promise_with_undefined();
+            }
+        }
+
+        // Perform ! WritableStreamDefaultControllerClose(stream.[[controller]]).
+        let Some(controller) = self.controller.get() else {
+            unreachable!("Stream must have a controller.");
+        };
+        controller.close(cx, global, can_gc);
+
+        // Return promise.
+        promise
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-get-desired-size>
+    /// Note: implement as a stream method, as opposed to a writer one, for convenience.
+    pub(crate) fn get_desired_size(&self) -> Option<f64> {
+        // Let stream be writer.[[stream]].
+        // Stream is `self`.
+
+        // Let state be stream.[[state]].
+        // If state is "errored" or "erroring", return null.
+        if self.is_errored() || self.is_erroring() {
+            return None;
+        }
+
+        // If state is "closed", return 0.
+        if self.is_closed() {
+            return Some(0.);
+        }
+
+        let Some(controller) = self.controller.get() else {
+            unreachable!("Stream must have a controller.");
+        };
+        Some(controller.get_desired_size())
+    }
+
+    /// <https://streams.spec.whatwg.org/#acquire-writable-stream-default-writer>
+    pub(crate) fn aquire_default_writer(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) -> Result<DomRoot<WritableStreamDefaultWriter>, Error> {
+        // Let writer be a new WritableStreamDefaultWriter object.
+        let writer = WritableStreamDefaultWriter::new(global, None, can_gc);
+
+        // Perform ? SetUpWritableStreamDefaultWriter(writer, stream).
+        writer.setup(cx, self)?;
+
+        // Return writer.
+        Ok(writer)
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-update-backpressure>
+    pub(crate) fn update_backpressure(
+        &self,
+        backpressure: bool,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) {
+        // Assert: stream.[[state]] is "writable".
+        self.is_writable();
+
+        // Assert: ! WritableStreamCloseQueuedOrInFlight(stream) is false.
+        assert!(!self.close_queued_or_in_flight());
+
+        // Let writer be stream.[[writer]].
+        let writer = self.get_writer();
+        if writer.is_some() && backpressure != self.get_backpressure() {
+            // If writer is not undefined
+            let writer = writer.expect("Writer is some, as per the above check.");
+            // and backpressure is not stream.[[backpressure]],
+            if backpressure {
+                // If backpressure is true, set writer.[[readyPromise]] to a new promise.
+                let promise = Promise::new(global, can_gc);
+                writer.set_ready_promise(promise);
+            } else {
+                // Otherwise,
+                // Assert: backpressure is false.
+                assert!(!backpressure);
+                // Resolve writer.[[readyPromise]] with undefined.
+                writer.resolve_ready_promise_with_undefined();
+            }
+        };
+
+        // Set stream.[[backpressure]] to backpressure.
+        self.set_backpressure(backpressure);
+    }
+}
+
+impl WritableStreamMethods<crate::DomTypeHolder> for WritableStream {
+    /// <https://streams.spec.whatwg.org/#ws-constructor>
+    fn Constructor(
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        proto: Option<SafeHandleObject>,
+        can_gc: CanGc,
+        underlying_sink: Option<*mut JSObject>,
+        strategy: &QueuingStrategy,
+    ) -> Fallible<DomRoot<WritableStream>> {
+        // If underlyingSink is missing, set it to null.
+        rooted!(in(*cx) let underlying_sink_obj = underlying_sink.unwrap_or(ptr::null_mut()));
+
+        // Let underlyingSinkDict be underlyingSink,
+        // converted to an IDL value of type UnderlyingSink.
+        let underlying_sink_dict = if !underlying_sink_obj.is_null() {
+            rooted!(in(*cx) let obj_val = ObjectValue(underlying_sink_obj.get()));
+            match UnderlyingSink::new(cx, obj_val.handle()) {
+                Ok(ConversionResult::Success(val)) => val,
+                Ok(ConversionResult::Failure(error)) => return Err(Error::Type(error.to_string())),
+                _ => {
+                    return Err(Error::JSFailed);
+                },
+            }
+        } else {
+            UnderlyingSink::empty()
+        };
+
+        if !underlying_sink_dict.type_.handle().is_undefined() {
+            // If underlyingSinkDict["type"] exists, throw a RangeError exception.
+            return Err(Error::Range("type is set".to_string()));
+        }
+
+        // Perform ! InitializeWritableStream(this).
+        let stream = WritableStream::new_with_proto(global, proto, can_gc);
+
+        // Let sizeAlgorithm be ! ExtractSizeAlgorithm(strategy).
+        let size_algorithm = extract_size_algorithm(strategy);
+
+        // Let highWaterMark be ? ExtractHighWaterMark(strategy, 1).
+        let high_water_mark = extract_high_water_mark(strategy, 1.0)?;
+
+        // Perform ? SetUpWritableStreamDefaultControllerFromUnderlyingSink
+        let controller = WritableStreamDefaultController::new(
+            global,
+            &underlying_sink_dict,
+            high_water_mark,
+            size_algorithm,
+            can_gc,
+        );
+
+        // Note: this must be done before `setup`,
+        // otherwise `thisOb` is null in the start callback.
+        controller.set_underlying_sink_this_object(underlying_sink_obj.handle());
+
+        // Perform ? SetUpWritableStreamDefaultController
+        controller.setup(cx, global, &stream, &underlying_sink_dict.start, can_gc)?;
+
+        Ok(stream)
+    }
+
+    /// <https://streams.spec.whatwg.org/#ws-locked>
+    fn Locked(&self) -> bool {
+        // Return ! IsWritableStreamLocked(this).
+        self.is_locked()
+    }
+
+    /// <https://streams.spec.whatwg.org/#ws-abort>
+    fn Abort(
+        &self,
+        cx: SafeJSContext,
+        reason: SafeHandleValue,
+        realm: InRealm,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // If ! IsWritableStreamLocked(this) is true,
+        if self.is_locked() {
+            // return a promise rejected with a TypeError exception.
+            let promise = Promise::new(&global, can_gc);
+            promise.reject_error(Error::Type("Stream is locked.".to_string()));
+            return promise;
+        }
+
+        // Return ! WritableStreamAbort(this, reason).
+        self.abort(cx, &global, reason, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#ws-close>
+    fn Close(&self, realm: InRealm, can_gc: CanGc) -> Rc<Promise> {
+        let cx = GlobalScope::get_cx();
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // If ! IsWritableStreamLocked(this) is true,
+        if self.is_locked() {
+            // return a promise rejected with a TypeError exception.
+            let promise = Promise::new(&global, can_gc);
+            promise.reject_error(Error::Type("Stream is locked.".to_string()));
+            return promise;
+        }
+
+        // If ! WritableStreamCloseQueuedOrInFlight(this) is true
+        if self.close_queued_or_in_flight() {
+            // return a promise rejected with a TypeError exception.
+            let promise = Promise::new(&global, can_gc);
+            promise.reject_error(Error::Type(
+                "Stream has closed queued or in-flight".to_string(),
+            ));
+            return promise;
+        }
+
+        // Return ! WritableStreamClose(this).
+        self.close(cx, &global, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#ws-get-writer>
+    fn GetWriter(
+        &self,
+        realm: InRealm,
+        can_gc: CanGc,
+    ) -> Result<DomRoot<WritableStreamDefaultWriter>, Error> {
+        let cx = GlobalScope::get_cx();
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Return ? AcquireWritableStreamDefaultWriter(this).
+        self.aquire_default_writer(cx, &global, can_gc)
+    }
+}
diff --git a/components/script/dom/writablestreamdefaultcontroller.rs b/components/script/dom/writablestreamdefaultcontroller.rs
new file mode 100644
index 00000000000..cd027907211
--- /dev/null
+++ b/components/script/dom/writablestreamdefaultcontroller.rs
@@ -0,0 +1,829 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::cell::{Cell, RefCell};
+use std::ptr;
+use std::rc::Rc;
+
+use dom_struct::dom_struct;
+use js::jsapi::{Heap, IsPromiseObject, JSObject};
+use js::jsval::{JSVal, UndefinedValue};
+use js::rust::{HandleObject as SafeHandleObject, HandleValue as SafeHandleValue, IntoHandle};
+
+use super::bindings::codegen::Bindings::QueuingStrategyBinding::QueuingStrategySize;
+use crate::dom::bindings::callback::ExceptionHandling;
+use crate::dom::bindings::codegen::Bindings::UnderlyingSinkBinding::{
+    UnderlyingSink, UnderlyingSinkAbortCallback, UnderlyingSinkCloseCallback,
+    UnderlyingSinkStartCallback, UnderlyingSinkWriteCallback,
+};
+use crate::dom::bindings::codegen::Bindings::WritableStreamDefaultControllerBinding::WritableStreamDefaultControllerMethods;
+use crate::dom::bindings::error::Error;
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use crate::dom::promisenativehandler::{Callback, PromiseNativeHandler};
+use crate::dom::readablestreamdefaultcontroller::{EnqueuedValue, QueueWithSizes, ValueWithSize};
+use crate::dom::writablestream::WritableStream;
+use crate::realms::{enter_realm, InRealm};
+use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
+
+impl js::gc::Rootable for CloseAlgorithmFulfillmentHandler {}
+
+/// The fulfillment handler for
+/// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-close>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct CloseAlgorithmFulfillmentHandler {
+    stream: Dom<WritableStream>,
+}
+
+impl Callback for CloseAlgorithmFulfillmentHandler {
+    fn callback(&self, cx: SafeJSContext, _v: SafeHandleValue, _realm: InRealm, _can_gc: CanGc) {
+        let stream = self.stream.as_rooted();
+
+        // Perform ! WritableStreamFinishInFlightClose(stream).
+        stream.finish_in_flight_close(cx);
+    }
+}
+
+impl js::gc::Rootable for CloseAlgorithmRejectionHandler {}
+
+/// The rejection handler for
+/// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-close>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct CloseAlgorithmRejectionHandler {
+    stream: Dom<WritableStream>,
+}
+
+impl Callback for CloseAlgorithmRejectionHandler {
+    fn callback(&self, cx: SafeJSContext, v: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        let stream = self.stream.as_rooted();
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Perform ! WritableStreamFinishInFlightCloseWithError(stream, reason).
+        stream.finish_in_flight_close_with_error(cx, &global, v, can_gc);
+    }
+}
+
+impl js::gc::Rootable for StartAlgorithmFulfillmentHandler {}
+
+/// The fulfillment handler for
+/// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct StartAlgorithmFulfillmentHandler {
+    controller: Dom<WritableStreamDefaultController>,
+}
+
+impl Callback for StartAlgorithmFulfillmentHandler {
+    /// Continuation of <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+    /// Upon fulfillment of startPromise,
+    fn callback(&self, cx: SafeJSContext, _v: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        let controller = self.controller.as_rooted();
+        let stream = controller
+            .stream
+            .get()
+            .expect("Controller should have a stream.");
+
+        // Assert: stream.[[state]] is "writable" or "erroring".
+        assert!(stream.is_erroring() || stream.is_writable());
+
+        // Set controller.[[started]] to true.
+        controller.started.set(true);
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Perform ! WritableStreamDefaultControllerAdvanceQueueIfNeeded(controller).
+        controller.advance_queue_if_needed(cx, &global, can_gc)
+    }
+}
+
+impl js::gc::Rootable for StartAlgorithmRejectionHandler {}
+
+/// The rejection handler for
+/// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct StartAlgorithmRejectionHandler {
+    controller: Dom<WritableStreamDefaultController>,
+}
+
+impl Callback for StartAlgorithmRejectionHandler {
+    /// Continuation of <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller>
+    /// Upon rejection of startPromise with reason r,
+    fn callback(&self, cx: SafeJSContext, v: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        let controller = self.controller.as_rooted();
+        let stream = controller
+            .stream
+            .get()
+            .expect("Controller should have a stream.");
+
+        // Assert: stream.[[state]] is "writable" or "erroring".
+        assert!(stream.is_erroring() || stream.is_writable());
+
+        // Set controller.[[started]] to true.
+        controller.started.set(true);
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Perform ! WritableStreamDealWithRejection(stream, r).
+        stream.deal_with_rejection(cx, &global, v, can_gc);
+    }
+}
+
+impl js::gc::Rootable for WriteAlgorithmFulfillmentHandler {}
+
+/// The fulfillment handler for
+/// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-write>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct WriteAlgorithmFulfillmentHandler {
+    controller: Dom<WritableStreamDefaultController>,
+}
+
+impl Callback for WriteAlgorithmFulfillmentHandler {
+    fn callback(&self, cx: SafeJSContext, _v: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        let controller = self.controller.as_rooted();
+        let stream = controller
+            .stream
+            .get()
+            .expect("Controller should have a stream.");
+
+        // Perform ! WritableStreamFinishInFlightWrite(stream).
+        stream.finish_in_flight_write();
+
+        // Let state be stream.[[state]].
+        // Assert: state is "writable" or "erroring".
+        assert!(stream.is_erroring() || stream.is_writable());
+
+        // Perform ! DequeueValue(controller).
+        {
+            rooted!(in(*cx) let mut rval = UndefinedValue());
+            let mut queue = controller.queue.borrow_mut();
+            queue.dequeue_value(cx, Some(rval.handle_mut()));
+        }
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // If ! WritableStreamCloseQueuedOrInFlight(stream) is false and state is "writable",
+        if !stream.close_queued_or_in_flight() && stream.is_writable() {
+            // Let backpressure be ! WritableStreamDefaultControllerGetBackpressure(controller).
+            let backpressure = controller.get_backpressure();
+
+            // Perform ! WritableStreamUpdateBackpressure(stream, backpressure).
+            stream.update_backpressure(backpressure, &global, can_gc);
+        }
+
+        // Perform ! WritableStreamDefaultControllerAdvanceQueueIfNeeded(controller).
+        controller.advance_queue_if_needed(cx, &global, can_gc)
+    }
+}
+
+impl js::gc::Rootable for WriteAlgorithmRejectionHandler {}
+
+/// The rejection handler for
+/// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-write>
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+struct WriteAlgorithmRejectionHandler {
+    controller: Dom<WritableStreamDefaultController>,
+}
+
+impl Callback for WriteAlgorithmRejectionHandler {
+    fn callback(&self, cx: SafeJSContext, v: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        let controller = self.controller.as_rooted();
+        let stream = controller
+            .stream
+            .get()
+            .expect("Controller should have a stream.");
+
+        // If stream.[[state]] is "writable",
+        if stream.is_writable() {
+            // perform ! WritableStreamDefaultControllerClearAlgorithms(controller).
+            controller.clear_algorithms();
+        }
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Perform ! WritableStreamFinishInFlightWriteWithError(stream, reason).
+        stream.finish_in_flight_write_with_error(cx, &global, v, can_gc);
+    }
+}
+
+/// <https://streams.spec.whatwg.org/#ws-default-controller-class>
+#[dom_struct]
+pub struct WritableStreamDefaultController {
+    reflector_: Reflector,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-abortalgorithm>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    abort: RefCell<Option<Rc<UnderlyingSinkAbortCallback>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-closealgorithm>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    close: RefCell<Option<Rc<UnderlyingSinkCloseCallback>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-writealgorithm>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    write: RefCell<Option<Rc<UnderlyingSinkWriteCallback>>>,
+
+    /// The JS object used as `this` when invoking sink algorithms.
+    #[ignore_malloc_size_of = "mozjs"]
+    underlying_sink_obj: Heap<*mut JSObject>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-queue>
+    queue: RefCell<QueueWithSizes>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-started>
+    started: Cell<bool>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-strategyhwm>
+    strategy_hwm: f64,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-strategysizealgorithm>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    strategy_size: RefCell<Option<Rc<QueuingStrategySize>>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultcontroller-stream>
+    stream: MutNullableDom<WritableStream>,
+}
+
+impl WritableStreamDefaultController {
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controller-from-underlying-sink>
+    #[cfg_attr(crown, allow(crown::unrooted_must_root))]
+    fn new_inherited(
+        underlying_sink: &UnderlyingSink,
+        strategy_hwm: f64,
+        strategy_size: Rc<QueuingStrategySize>,
+    ) -> WritableStreamDefaultController {
+        WritableStreamDefaultController {
+            reflector_: Reflector::new(),
+            queue: Default::default(),
+            stream: Default::default(),
+            abort: RefCell::new(underlying_sink.abort.clone()),
+            close: RefCell::new(underlying_sink.close.clone()),
+            write: RefCell::new(underlying_sink.write.clone()),
+            underlying_sink_obj: Default::default(),
+            strategy_hwm,
+            strategy_size: RefCell::new(Some(strategy_size)),
+            started: Default::default(),
+        }
+    }
+
+    pub(crate) fn new(
+        global: &GlobalScope,
+        underlying_sink: &UnderlyingSink,
+        strategy_hwm: f64,
+        strategy_size: Rc<QueuingStrategySize>,
+        can_gc: CanGc,
+    ) -> DomRoot<WritableStreamDefaultController> {
+        reflect_dom_object(
+            Box::new(WritableStreamDefaultController::new_inherited(
+                underlying_sink,
+                strategy_hwm,
+                strategy_size,
+            )),
+            global,
+            can_gc,
+        )
+    }
+
+    pub(crate) fn started(&self) -> bool {
+        self.started.get()
+    }
+
+    /// Setting the JS object after the heap has settled down.
+    pub(crate) fn set_underlying_sink_this_object(&self, this_object: SafeHandleObject) {
+        self.underlying_sink_obj.set(*this_object);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-clear-algorithms>
+    fn clear_algorithms(&self) {
+        // Set controller.[[writeAlgorithm]] to undefined.
+        self.write.borrow_mut().take();
+
+        // Set controller.[[closeAlgorithm]] to undefined.
+        self.close.borrow_mut().take();
+
+        // Set controller.[[abortAlgorithm]] to undefined.
+        self.abort.borrow_mut().take();
+
+        // Set controller.[[strategySizeAlgorithm]] to undefined.
+        self.strategy_size.borrow_mut().take();
+    }
+
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-controllerr>
+    #[allow(unsafe_code)]
+    pub(crate) fn setup(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        stream: &WritableStream,
+        start: &Option<Rc<UnderlyingSinkStartCallback>>,
+        can_gc: CanGc,
+    ) -> Result<(), Error> {
+        // Assert: stream implements WritableStream.
+        // Implied by stream type.
+
+        // Assert: stream.[[controller]] is undefined.
+        stream.assert_no_controller();
+
+        // Set controller.[[stream]] to stream.
+        self.stream.set(Some(stream));
+
+        // Set stream.[[controller]] to controller.
+        stream.set_default_controller(self);
+
+        // Perform ! ResetQueue(controller).
+
+        // Set controller.[[abortController]] to a new AbortController.
+
+        // Set controller.[[started]] to false.
+
+        // Set controller.[[strategySizeAlgorithm]] to sizeAlgorithm.
+
+        // Set controller.[[strategyHWM]] to highWaterMark.
+
+        // Set controller.[[writeAlgorithm]] to writeAlgorithm.
+
+        // Set controller.[[closeAlgorithm]] to closeAlgorithm.
+
+        // Set controller.[[abortAlgorithm]] to abortAlgorithm.
+
+        // Note: above steps are done in `new_inherited`.
+
+        // Let backpressure be ! WritableStreamDefaultControllerGetBackpressure(controller).
+        let backpressure = self.get_backpressure();
+
+        // Perform ! WritableStreamUpdateBackpressure(stream, backpressure).
+        stream.update_backpressure(backpressure, global, can_gc);
+
+        // Let startResult be the result of performing startAlgorithm. (This may throw an exception.)
+        // Let startPromise be a promise resolved with startResult.
+        let start_promise = if let Some(start) = start {
+            rooted!(in(*cx) let mut result_object = ptr::null_mut::<JSObject>());
+            rooted!(in(*cx) let mut result: JSVal);
+            rooted!(in(*cx) let this_object = self.underlying_sink_obj.get());
+            start.Call_(
+                &this_object.handle(),
+                self,
+                result.handle_mut(),
+                ExceptionHandling::Rethrow,
+            )?;
+            let is_promise = unsafe {
+                if result.is_object() {
+                    result_object.set(result.to_object());
+                    IsPromiseObject(result_object.handle().into_handle())
+                } else {
+                    false
+                }
+            };
+            if is_promise {
+                let promise = Promise::new_with_js_promise(result_object.handle(), cx);
+                promise
+            } else {
+                let promise = Promise::new(global, can_gc);
+                promise.resolve_native(&result.get());
+                promise
+            }
+        } else {
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&());
+            promise
+        };
+
+        let rooted_default_controller = DomRoot::from_ref(self);
+
+        // Upon fulfillment of startPromise,
+        rooted!(in(*cx) let mut fulfillment_handler = Some(StartAlgorithmFulfillmentHandler {
+            controller: Dom::from_ref(&rooted_default_controller),
+        }));
+
+        // Upon rejection of startPromise with reason r,
+        rooted!(in(*cx) let mut rejection_handler = Some(StartAlgorithmRejectionHandler {
+            controller: Dom::from_ref(&rooted_default_controller),
+        }));
+
+        let handler = PromiseNativeHandler::new(
+            global,
+            fulfillment_handler.take().map(|h| Box::new(h) as Box<_>),
+            rejection_handler.take().map(|h| Box::new(h) as Box<_>),
+        );
+        let realm = enter_realm(global);
+        let comp = InRealm::Entered(&realm);
+        start_promise.append_native_handler(&handler, comp, can_gc);
+
+        Ok(())
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-close>
+    pub(crate) fn close(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) {
+        // Perform ! EnqueueValueWithSize(controller, close sentinel, 0).
+        {
+            let mut queue = self.queue.borrow_mut();
+            queue
+                .enqueue_value_with_size(EnqueuedValue::CloseSentinel)
+                .expect("Enqueuing the close sentinel should not fail.");
+        }
+        // Perform ! WritableStreamDefaultControllerAdvanceQueueIfNeeded(controller).
+        self.advance_queue_if_needed(cx, global, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#ref-for-abstract-opdef-writablestreamcontroller-abortsteps>
+    pub(crate) fn abort_steps(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        reason: SafeHandleValue,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        rooted!(in(*cx) let this_object = self.underlying_sink_obj.get());
+        let algo = self.abort.borrow().clone();
+        let result = if let Some(algo) = algo {
+            algo.Call_(
+                &this_object.handle(),
+                Some(reason),
+                ExceptionHandling::Rethrow,
+            )
+        } else {
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&());
+            Ok(promise)
+        };
+        result.unwrap_or_else(|e| {
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(e);
+            promise
+        })
+    }
+
+    pub(crate) fn call_write_algorithm(
+        &self,
+        cx: SafeJSContext,
+        chunk: SafeHandleValue,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        rooted!(in(*cx) let this_object = self.underlying_sink_obj.get());
+        let algo = self.write.borrow().clone();
+        let result = if let Some(algo) = algo {
+            algo.Call_(
+                &this_object.handle(),
+                chunk,
+                self,
+                ExceptionHandling::Rethrow,
+            )
+        } else {
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&());
+            Ok(promise)
+        };
+        result.unwrap_or_else(|e| {
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(e);
+            promise
+        })
+    }
+
+    fn call_close_algorithm(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        rooted!(in(*cx) let mut this_object = ptr::null_mut::<JSObject>());
+        this_object.set(self.underlying_sink_obj.get());
+        let algo = self.close.borrow().clone();
+        let result = if let Some(algo) = algo {
+            algo.Call_(&this_object.handle(), ExceptionHandling::Rethrow)
+        } else {
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&());
+            Ok(promise)
+        };
+        result.unwrap_or_else(|e| {
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(e);
+            promise
+        })
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-close>
+    pub(crate) fn process_close(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) {
+        // Let stream be controller.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // Perform ! WritableStreamMarkCloseRequestInFlight(stream).
+        stream.mark_close_request_in_flight();
+
+        // Perform ! DequeueValue(controller).
+        {
+            let mut queue = self.queue.borrow_mut();
+            queue.dequeue_value(cx, None);
+        }
+
+        // Assert: controller.[[queue]] is empty.
+        assert!(self.queue.borrow().is_empty());
+
+        // Let sinkClosePromise be the result of performing controller.[[closeAlgorithm]].
+        let sink_close_promise = self.call_close_algorithm(cx, global, can_gc);
+
+        // Perform ! WritableStreamDefaultControllerClearAlgorithms(controller).
+        self.clear_algorithms();
+
+        // Upon fulfillment of sinkClosePromise,
+        rooted!(in(*cx) let mut fulfillment_handler = Some(CloseAlgorithmFulfillmentHandler {
+            stream: Dom::from_ref(&stream),
+        }));
+
+        // Upon rejection of sinkClosePromise with reason reason,
+        rooted!(in(*cx) let mut rejection_handler = Some(CloseAlgorithmRejectionHandler {
+            stream: Dom::from_ref(&stream),
+        }));
+
+        // Attach handlers to the promise.
+        let handler = PromiseNativeHandler::new(
+            global,
+            fulfillment_handler.take().map(|h| Box::new(h) as Box<_>),
+            rejection_handler.take().map(|h| Box::new(h) as Box<_>),
+        );
+        let realm = enter_realm(global);
+        let comp = InRealm::Entered(&realm);
+        sink_close_promise.append_native_handler(&handler, comp, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-advance-queue-if-needed>
+    fn advance_queue_if_needed(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) {
+        // Let stream be controller.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // If controller.[[started]] is false, return.
+        if !self.started.get() {
+            return;
+        }
+
+        // If stream.[[inFlightWriteRequest]] is not undefined, return.
+        if stream.has_in_flight_write_request() {
+            return;
+        }
+
+        // Let state be stream.[[state]].
+
+        // Assert: state is not "closed" or "errored".
+        assert!(!(stream.is_errored() || stream.is_closed()));
+
+        // If state is "erroring",
+        if stream.is_erroring() {
+            // Perform ! WritableStreamFinishErroring(stream).
+            stream.finish_erroring(cx, global, can_gc);
+
+            // Return.
+            return;
+        }
+
+        // Let value be ! PeekQueueValue(controller).
+        rooted!(in(*cx) let mut value = UndefinedValue());
+        let is_closed = {
+            let queue = self.queue.borrow_mut();
+
+            // If controller.[[queue]] is empty, return.
+            if queue.is_empty() {
+                return;
+            }
+            queue.peek_queue_value(cx, value.handle_mut())
+        };
+
+        if is_closed {
+            // If value is the close sentinel, perform ! WritableStreamDefaultControllerProcessClose(controller).
+            self.process_close(cx, global, can_gc);
+        } else {
+            // Otherwise, perform ! WritableStreamDefaultControllerProcessWrite(controller, value).
+            self.process_write(cx, value.handle(), global, can_gc);
+        };
+    }
+
+    /// <https://streams.spec.whatwg.org/#ws-default-controller-private-error>
+    pub(crate) fn perform_error_steps(&self) {
+        // Perform ! ResetQueue(this).
+        self.queue.borrow_mut().reset();
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-process-write>
+    fn process_write(
+        &self,
+        cx: SafeJSContext,
+        chunk: SafeHandleValue,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) {
+        // Let stream be controller.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // Perform ! WritableStreamMarkFirstWriteRequestInFlight(stream).
+        stream.mark_first_write_request_in_flight();
+
+        // Let sinkWritePromise be the result of performing controller.[[writeAlgorithm]], passing in chunk.
+        let sink_write_promise = self.call_write_algorithm(cx, chunk, global, can_gc);
+
+        // Upon fulfillment of sinkWritePromise,
+        rooted!(in(*cx) let mut fulfillment_handler = Some(WriteAlgorithmFulfillmentHandler {
+            controller: Dom::from_ref(self),
+        }));
+
+        // Upon rejection of sinkWritePromise with reason,
+        rooted!(in(*cx) let mut rejection_handler = Some(WriteAlgorithmRejectionHandler {
+            controller: Dom::from_ref(self),
+        }));
+
+        // Attach handlers to the promise.
+        let handler = PromiseNativeHandler::new(
+            global,
+            fulfillment_handler.take().map(|h| Box::new(h) as Box<_>),
+            rejection_handler.take().map(|h| Box::new(h) as Box<_>),
+        );
+        let realm = enter_realm(global);
+        let comp = InRealm::Entered(&realm);
+        sink_write_promise.append_native_handler(&handler, comp, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-get-desired-size>
+    pub(crate) fn get_desired_size(&self) -> f64 {
+        // Return controller.[[strategyHWM]] − controller.[[queueTotalSize]].
+        let queue = self.queue.borrow();
+        let desired_size = self.strategy_hwm - queue.total_size.clamp(0.0, f64::MAX);
+        desired_size.clamp(desired_size, self.strategy_hwm)
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-get-backpressure>
+    fn get_backpressure(&self) -> bool {
+        // Let desiredSize be ! WritableStreamDefaultControllerGetDesiredSize(controller).
+        let desired_size = self.get_desired_size();
+
+        // Return true if desiredSize ≤ 0, or false otherwise.
+        desired_size == 0.0 || desired_size.is_sign_negative()
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-get-chunk-size>
+    pub(crate) fn get_chunk_size(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        chunk: SafeHandleValue,
+        can_gc: CanGc,
+    ) -> f64 {
+        // If controller.[[strategySizeAlgorithm]] is undefined,
+        let Some(strategy_size) = self.strategy_size.borrow().clone() else {
+            // Assert: controller.[[stream]].[[state]] is "erroring" or "errored".
+            let Some(stream) = self.stream.get() else {
+                unreachable!("Controller should have a stream");
+            };
+            assert!(stream.is_erroring() || stream.is_errored());
+
+            // Return 1.
+            return 1.0;
+        };
+
+        // Let returnValue be the result of performing controller.[[strategySizeAlgorithm]],
+        // passing in chunk, and interpreting the result as a completion record.
+        let result = strategy_size.Call__(chunk, ExceptionHandling::Rethrow);
+
+        match result {
+            // Let chunkSize be result.[[Value]].
+            Ok(size) => size,
+            Err(error) => {
+                // If result is an abrupt completion,
+
+                // Perform ! WritableStreamDefaultControllerErrorIfNeeded(controller, returnValue.[[Value]]).
+                // Create a rooted value for the error.
+                rooted!(in(*cx) let mut rooted_error = UndefinedValue());
+                error.to_jsval(cx, global, rooted_error.handle_mut());
+                self.error_if_needed(cx, rooted_error.handle(), global, can_gc);
+
+                // Return 1.
+                1.0
+            },
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-write>
+    pub(crate) fn write(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        chunk: SafeHandleValue,
+        chunk_size: f64,
+        can_gc: CanGc,
+    ) {
+        // Let enqueueResult be EnqueueValueWithSize(controller, chunk, chunkSize).
+        let enqueue_result = {
+            let mut queue = self.queue.borrow_mut();
+            queue.enqueue_value_with_size(EnqueuedValue::Js(ValueWithSize {
+                value: Heap::boxed(chunk.get()),
+                size: chunk_size,
+            }))
+        };
+
+        // If enqueueResult is an abrupt completion,
+        if let Err(error) = enqueue_result {
+            // Perform ! WritableStreamDefaultControllerErrorIfNeeded(controller, enqueueResult.[[Value]]).
+            // Create a rooted value for the error.
+            rooted!(in(*cx) let mut rooted_error = UndefinedValue());
+            error.to_jsval(cx, global, rooted_error.handle_mut());
+            self.error_if_needed(cx, rooted_error.handle(), global, can_gc);
+
+            // Return.
+            return;
+        }
+
+        // Let stream be controller.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // If ! WritableStreamCloseQueuedOrInFlight(stream) is false and stream.[[state]] is "writable",
+        if !stream.close_queued_or_in_flight() && stream.is_writable() {
+            // Let backpressure be ! WritableStreamDefaultControllerGetBackpressure(controller).
+            let backpressure = self.get_backpressure();
+
+            // Perform ! WritableStreamUpdateBackpressure(stream, backpressure).
+            stream.update_backpressure(backpressure, global, can_gc);
+        }
+
+        // Perform ! WritableStreamDefaultControllerAdvanceQueueIfNeeded(controller).
+        self.advance_queue_if_needed(cx, global, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-error-if-needed>
+    pub(crate) fn error_if_needed(
+        &self,
+        cx: SafeJSContext,
+        error: SafeHandleValue,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) {
+        // Let stream be controller.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // If stream.[[state]] is "writable",
+        if stream.is_writable() {
+            // Perform ! WritableStreamDefaultControllerError(controller, e).
+            self.error(&stream, cx, error, global, can_gc);
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-controller-error>
+    fn error(
+        &self,
+        stream: &WritableStream,
+        cx: SafeJSContext,
+        e: SafeHandleValue,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) {
+        // Let stream be controller.[[stream]].
+        // Done above with the argument.
+
+        // Assert: stream.[[state]] is "writable".
+        assert!(stream.is_writable());
+
+        // Perform ! WritableStreamDefaultControllerClearAlgorithms(controller).
+        self.clear_algorithms();
+
+        // Perform ! WritableStreamStartErroring(stream, error).
+        stream.start_erroring(cx, global, e, can_gc);
+    }
+}
+
+impl WritableStreamDefaultControllerMethods<crate::DomTypeHolder>
+    for WritableStreamDefaultController
+{
+    /// <https://streams.spec.whatwg.org/#ws-default-controller-error>
+    fn Error(&self, cx: SafeJSContext, e: SafeHandleValue, realm: InRealm, can_gc: CanGc) {
+        // Let state be this.[[stream]].[[state]].
+        let Some(stream) = self.stream.get() else {
+            unreachable!("Controller should have a stream");
+        };
+
+        // If state is not "writable", return.
+        if !stream.is_writable() {
+            return;
+        }
+
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // Perform ! WritableStreamDefaultControllerError(this, e).
+        self.error(&stream, cx, e, &global, can_gc);
+    }
+}
diff --git a/components/script/dom/writablestreamdefaultwriter.rs b/components/script/dom/writablestreamdefaultwriter.rs
new file mode 100644
index 00000000000..2a01f5347c6
--- /dev/null
+++ b/components/script/dom/writablestreamdefaultwriter.rs
@@ -0,0 +1,500 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use dom_struct::dom_struct;
+use js::jsval::UndefinedValue;
+use js::rust::{HandleObject as SafeHandleObject, HandleValue as SafeHandleValue};
+
+use crate::dom::bindings::codegen::Bindings::WritableStreamDefaultWriterBinding::WritableStreamDefaultWriterMethods;
+use crate::dom::bindings::error::Error;
+use crate::dom::bindings::reflector::{reflect_dom_object_with_proto, DomGlobal, Reflector};
+use crate::dom::bindings::root::{DomRoot, MutNullableDom};
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use crate::dom::writablestream::WritableStream;
+use crate::realms::InRealm;
+use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
+
+/// <https://streams.spec.whatwg.org/#writablestreamdefaultwriter>
+#[dom_struct]
+pub struct WritableStreamDefaultWriter {
+    reflector_: Reflector,
+
+    #[ignore_malloc_size_of = "Rc is hard"]
+    ready_promise: RefCell<Rc<Promise>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultwriter-closedpromise>
+    #[ignore_malloc_size_of = "Rc is hard"]
+    closed_promise: RefCell<Rc<Promise>>,
+
+    /// <https://streams.spec.whatwg.org/#writablestreamdefaultwriter-stream>
+    stream: MutNullableDom<WritableStream>,
+}
+
+impl WritableStreamDefaultWriter {
+    #[cfg_attr(crown, allow(crown::unrooted_must_root))]
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-writer>
+    /// The parts that create a new promise.
+    fn new_inherited(global: &GlobalScope, can_gc: CanGc) -> WritableStreamDefaultWriter {
+        WritableStreamDefaultWriter {
+            reflector_: Reflector::new(),
+            stream: Default::default(),
+            closed_promise: RefCell::new(Promise::new(global, can_gc)),
+            ready_promise: RefCell::new(Promise::new(global, can_gc)),
+        }
+    }
+
+    pub(crate) fn new(
+        global: &GlobalScope,
+        proto: Option<SafeHandleObject>,
+        can_gc: CanGc,
+    ) -> DomRoot<WritableStreamDefaultWriter> {
+        reflect_dom_object_with_proto(
+            Box::new(WritableStreamDefaultWriter::new_inherited(global, can_gc)),
+            global,
+            proto,
+            can_gc,
+        )
+    }
+
+    /// <https://streams.spec.whatwg.org/#set-up-writable-stream-default-writer>
+    /// Continuing from `new_inherited`, the rest.
+    pub(crate) fn setup(&self, cx: SafeJSContext, stream: &WritableStream) -> Result<(), Error> {
+        // If ! IsWritableStreamLocked(stream) is true, throw a TypeError exception.
+        if stream.is_locked() {
+            return Err(Error::Type("Stream is locked".to_string()));
+        }
+
+        // Set writer.[[stream]] to stream.
+        self.stream.set(Some(stream));
+
+        // Set stream.[[writer]] to writer.
+        stream.set_writer(Some(self));
+
+        // Let state be stream.[[state]].
+
+        // If state is "writable",
+        if stream.is_writable() {
+            // If ! WritableStreamCloseQueuedOrInFlight(stream) is false
+            // and stream.[[backpressure]] is true,
+            if !stream.close_queued_or_in_flight() && stream.get_backpressure() {
+                // set writer.[[readyPromise]] to a new promise.
+                // Done in `new_inherited`.
+            } else {
+                // Otherwise, set writer.[[readyPromise]] to a promise resolved with undefined.
+                // Note: new promise created in `new_inherited`.
+                self.ready_promise.borrow().resolve_native(&());
+            }
+
+            // Set writer.[[closedPromise]] to a new promise.
+            // Done in `new_inherited`.
+            return Ok(());
+        }
+
+        // Otherwise, if state is "erroring",
+        if stream.is_erroring() {
+            rooted!(in(*cx) let mut error = UndefinedValue());
+            stream.get_stored_error(error.handle_mut());
+
+            // Set writer.[[readyPromise]] to a promise rejected with stream.[[storedError]].
+            // Set writer.[[readyPromise]].[[PromiseIsHandled]] to true.
+            // Note: new promise created in `new_inherited`.
+            let ready_promise = self.ready_promise.borrow();
+            ready_promise.reject_native(&error.handle());
+            ready_promise.set_promise_is_handled();
+
+            // Set writer.[[closedPromise]] to a new promise.
+            // Done in `new_inherited`.
+            return Ok(());
+        }
+
+        // Otherwise, if state is "closed",
+        if stream.is_closed() {
+            // Set writer.[[readyPromise]] to a promise resolved with undefined.
+            // Note: new promise created in `new_inherited`.
+            self.ready_promise.borrow().resolve_native(&());
+
+            // Set writer.[[closedPromise]] to a promise resolved with undefined.
+            // Note: new promise created in `new_inherited`.
+            self.closed_promise.borrow().resolve_native(&());
+            return Ok(());
+        }
+
+        // Otherwise,
+        // Assert: state is "errored".
+        assert!(stream.is_errored());
+
+        // Let storedError be stream.[[storedError]].
+        rooted!(in(*cx) let mut error = UndefinedValue());
+        stream.get_stored_error(error.handle_mut());
+
+        // Set writer.[[readyPromise]] to a promise rejected with stream.[[storedError]].
+        // Set writer.[[readyPromise]].[[PromiseIsHandled]] to true.
+        // Note: new promise created in `new_inherited`.
+        let ready_promise = self.ready_promise.borrow();
+        ready_promise.reject_native(&error.handle());
+        ready_promise.set_promise_is_handled();
+
+        // Set writer.[[closedPromise]] to a promise rejected with storedError.
+        // Set writer.[[closedPromise]].[[PromiseIsHandled]] to true.
+        // Note: new promise created in `new_inherited`.
+        let ready_promise = self.closed_promise.borrow();
+        ready_promise.reject_native(&error.handle());
+        ready_promise.set_promise_is_handled();
+
+        Ok(())
+    }
+
+    pub(crate) fn reject_closed_promise_with_stored_error(&self, error: &SafeHandleValue) {
+        self.closed_promise.borrow().reject_native(error);
+    }
+
+    pub(crate) fn set_close_promise_is_handled(&self) {
+        self.closed_promise.borrow().set_promise_is_handled();
+    }
+
+    pub(crate) fn set_ready_promise(&self, promise: Rc<Promise>) {
+        *self.ready_promise.borrow_mut() = promise;
+    }
+
+    pub(crate) fn resolve_ready_promise_with_undefined(&self) {
+        self.ready_promise.borrow().resolve_native(&());
+    }
+
+    pub(crate) fn resolve_closed_promise_with_undefined(&self) {
+        self.closed_promise.borrow().resolve_native(&());
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-ensure-ready-promise-rejected>
+    pub(crate) fn ensure_ready_promise_rejected(
+        &self,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        let ready_promise = self.ready_promise.borrow().clone();
+
+        // If writer.[[readyPromise]].[[PromiseState]] is "pending",
+        if ready_promise.is_pending() {
+            // reject writer.[[readyPromise]] with error.
+            ready_promise.reject_native(&error);
+
+            // Set writer.[[readyPromise]].[[PromiseIsHandled]] to true.
+            ready_promise.set_promise_is_handled();
+        } else {
+            // Otherwise, set writer.[[readyPromise]] to a promise rejected with error.
+            let promise = Promise::new(global, can_gc);
+            promise.reject_native(&error);
+
+            // Set writer.[[readyPromise]].[[PromiseIsHandled]] to true.
+            promise.set_promise_is_handled();
+            *self.ready_promise.borrow_mut() = promise;
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-ensure-closed-promise-rejected>
+    pub(crate) fn ensure_closed_promise_rejected(
+        &self,
+        global: &GlobalScope,
+        error: SafeHandleValue,
+        can_gc: CanGc,
+    ) {
+        let closed_promise = self.closed_promise.borrow().clone();
+
+        // If writer.[[closedPromise]].[[PromiseState]] is "pending",
+        if closed_promise.is_pending() {
+            // reject writer.[[closedPromise]] with error.
+            closed_promise.reject_native(&error);
+
+            // Set writer.[[closedPromise]].[[PromiseIsHandled]] to true.
+            closed_promise.set_promise_is_handled();
+        } else {
+            // Otherwise, set writer.[[closedPromise]] to a promise rejected with error.
+            let promise = Promise::new(global, can_gc);
+            promise.reject_native(&error);
+
+            // Set writer.[[closedPromise]].[[PromiseIsHandled]] to true.
+            promise.set_promise_is_handled();
+            *self.closed_promise.borrow_mut() = promise;
+        }
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-abort>
+    fn abort(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        reason: SafeHandleValue,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        // Let stream be writer.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // Assert: stream is not undefined.
+            unreachable!("Stream should be set.");
+        };
+
+        // Return ! WritableStreamAbort(stream, reason).
+        stream.abort(cx, global, reason, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-close>
+    fn close(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) -> Rc<Promise> {
+        // Let stream be writer.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // Assert: stream is not undefined.
+            unreachable!("Stream should be set.");
+        };
+
+        // Return ! WritableStreamClose(stream).
+        stream.close(cx, global, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-write>
+    fn write(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        chunk: SafeHandleValue,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        // Let stream be writer.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // Assert: stream is not undefined.
+            unreachable!("Stream should be set.");
+        };
+
+        // Let controller be stream.[[controller]].
+        // Note: asserting controller is some.
+        let Some(controller) = stream.get_controller() else {
+            unreachable!("Controller should be set.");
+        };
+
+        // Let chunkSize be ! WritableStreamDefaultControllerGetChunkSize(controller, chunk).
+        let chunk_size = controller.get_chunk_size(cx, global, chunk, can_gc);
+
+        // If stream is not equal to writer.[[stream]],
+        // return a promise rejected with a TypeError exception.
+        if !self
+            .stream
+            .get()
+            .map_or(false, |current_stream| current_stream == stream)
+        {
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(Error::Type(
+                "Stream is not equal to writer stream".to_string(),
+            ));
+            return promise;
+        }
+
+        // Let state be stream.[[state]].
+        // If state is "errored",
+        if stream.is_errored() {
+            // return a promise rejected with stream.[[storedError]].
+            rooted!(in(*cx) let mut error = UndefinedValue());
+            stream.get_stored_error(error.handle_mut());
+            let promise = Promise::new(global, can_gc);
+            promise.reject_native(&error.handle());
+            return promise;
+        }
+
+        // If ! WritableStreamCloseQueuedOrInFlight(stream) is true
+        // or state is "closed",
+        if stream.close_queued_or_in_flight() || stream.is_closed() {
+            // return a promise rejected with a TypeError exception
+            // indicating that the stream is closing or closed
+            let promise = Promise::new(global, can_gc);
+            promise.reject_error(Error::Type(
+                "Stream has been closed, or has close queued or in-flight".to_string(),
+            ));
+            return promise;
+        }
+
+        // If state is "erroring",
+        if stream.is_erroring() {
+            // return a promise rejected with stream.[[storedError]].
+            rooted!(in(*cx) let mut error = UndefinedValue());
+            stream.get_stored_error(error.handle_mut());
+            let promise = Promise::new(global, can_gc);
+            promise.reject_native(&error.handle());
+            return promise;
+        }
+
+        // Assert: state is "writable".
+        assert!(stream.is_writable());
+
+        // Let promise be ! WritableStreamAddWriteRequest(stream).
+        let promise = stream.add_write_request(global, can_gc);
+
+        // Perform ! WritableStreamDefaultControllerWrite(controller, chunk, chunkSize).
+        controller.write(cx, global, chunk, chunk_size, can_gc);
+
+        // Return promise.
+        promise
+    }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-release>
+    pub(crate) fn release(&self, cx: SafeJSContext, global: &GlobalScope, can_gc: CanGc) {
+        // Let stream be this.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // Assert: stream is not undefined.
+            unreachable!("Stream should be set.");
+        };
+
+        // Assert: stream.[[writer]] is writer.
+        assert!(stream.get_writer().is_some_and(|writer| &*writer == self));
+
+        // Let releasedError be a new TypeError.
+        let released_error = Error::Type("Writer has been released".to_string());
+
+        // Root the js val of the error.
+        rooted!(in(*cx) let mut error = UndefinedValue());
+        released_error.to_jsval(cx, global, error.handle_mut());
+
+        // Perform ! WritableStreamDefaultWriterEnsureReadyPromiseRejected(writer, releasedError).
+        self.ensure_ready_promise_rejected(global, error.handle(), can_gc);
+
+        // Perform ! WritableStreamDefaultWriterEnsureClosedPromiseRejected(writer, releasedError).
+        self.ensure_closed_promise_rejected(global, error.handle(), can_gc);
+
+        // Set stream.[[writer]] to undefined.
+        stream.set_writer(None);
+
+        // Set this.[[stream]] to undefined.
+        self.stream.set(None);
+    }
+}
+
+impl WritableStreamDefaultWriterMethods<crate::DomTypeHolder> for WritableStreamDefaultWriter {
+    /// <https://streams.spec.whatwg.org/#default-writer-closed>
+    fn Closed(&self) -> Rc<Promise> {
+        // Return this.[[closedPromise]].
+        return self.closed_promise.borrow().clone();
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-desired-size>
+    fn GetDesiredSize(&self) -> Result<Option<f64>, Error> {
+        // If this.[[stream]] is undefined, throw a TypeError exception.
+        let Some(stream) = self.stream.get() else {
+            return Err(Error::Type("Stream is undefined".to_string()));
+        };
+
+        // Return ! WritableStreamDefaultWriterGetDesiredSize(this).
+        Ok(stream.get_desired_size())
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-ready>
+    fn Ready(&self) -> Rc<Promise> {
+        // Return this.[[readyPromise]].
+        return self.ready_promise.borrow().clone();
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-abort>
+    fn Abort(
+        &self,
+        cx: SafeJSContext,
+        reason: SafeHandleValue,
+        realm: InRealm,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // If this.[[stream]] is undefined,
+        if self.stream.get().is_none() {
+            // return a promise rejected with a TypeError exception.
+            let promise = Promise::new(&global, can_gc);
+            promise.reject_error(Error::Type("Stream is undefined".to_string()));
+            return promise;
+        }
+
+        // Return ! WritableStreamDefaultWriterAbort(this, reason).
+        self.abort(cx, &global, reason, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-close>
+    fn Close(&self, in_realm: InRealm, can_gc: CanGc) -> Rc<Promise> {
+        let cx = GlobalScope::get_cx();
+        let global = GlobalScope::from_safe_context(cx, in_realm);
+        let promise = Promise::new(&global, can_gc);
+
+        // Let stream be this.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // If stream is undefined,
+            // return a promise rejected with a TypeError exception.
+            promise.reject_error(Error::Type("Stream is undefined".to_string()));
+            return promise;
+        };
+
+        // If ! WritableStreamCloseQueuedOrInFlight(stream) is true
+        if stream.close_queued_or_in_flight() {
+            // return a promise rejected with a TypeError exception.
+            promise.reject_error(Error::Type(
+                "Stream has closed queued or in-flight".to_string(),
+            ));
+            return promise;
+        }
+
+        self.close(cx, &global, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-release-lock>
+    fn ReleaseLock(&self, can_gc: CanGc) {
+        // Let stream be this.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // If stream is undefined, return.
+            return;
+        };
+
+        // Assert: stream.[[writer]] is not undefined.
+        assert!(stream.get_writer().is_some());
+
+        let global = self.global();
+        let cx = GlobalScope::get_cx();
+
+        // Perform ! WritableStreamDefaultWriterRelease(this).
+        self.release(cx, &global, can_gc);
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-write>
+    fn Write(
+        &self,
+        cx: SafeJSContext,
+        chunk: SafeHandleValue,
+        realm: InRealm,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        let global = GlobalScope::from_safe_context(cx, realm);
+
+        // If this.[[stream]] is undefined,
+        if self.stream.get().is_none() {
+            // return a promise rejected with a TypeError exception.
+            let global = GlobalScope::from_safe_context(cx, realm);
+            let promise = Promise::new(&global, can_gc);
+            promise.reject_error(Error::Type("Stream is undefined".to_string()));
+            return promise;
+        }
+
+        // Return ! WritableStreamDefaultWriterWrite(this, chunk).
+        self.write(cx, &global, chunk, can_gc)
+    }
+
+    /// <https://streams.spec.whatwg.org/#default-writer-constructor>
+    fn Constructor(
+        global: &GlobalScope,
+        proto: Option<SafeHandleObject>,
+        can_gc: CanGc,
+        stream: &WritableStream,
+    ) -> Result<DomRoot<WritableStreamDefaultWriter>, Error> {
+        let writer = WritableStreamDefaultWriter::new(global, proto, can_gc);
+
+        let cx = GlobalScope::get_cx();
+
+        // Perform ? SetUpWritableStreamDefaultWriter(this, stream).
+        writer.setup(cx, stream)?;
+
+        Ok(writer)
+    }
+}
author	Gregory Terzian <2792687+gterzian@users.noreply.github.com>	2025-02-19 20:02:14 +0700
committer	GitHub <noreply@github.com>	2025-02-19 13:02:14 +0000
commit	df6d6361688f487142809b5923e030447870e073 (patch)
tree	3e81927a47cfc98e8c895c8153eee47ee5758753 /components/script/dom
parent	720bc725b0c1cd5f01f9ff1d17793a3b1f32a480 (diff)
download	servo-df6d6361688f487142809b5923e030447870e073.tar.gz servo-df6d6361688f487142809b5923e030447870e073.zip