2 files changed, 22 insertions, 10 deletions

diff --git a/components/script/dom/htmlformelement.rs b/components/script/dom/htmlformelement.rs
index f7c3b7272a7..bccc2912772 100644
--- a/components/script/dom/htmlformelement.rs
+++ b/components/script/dom/htmlformelement.rs
@@ -219,16 +219,21 @@ impl HTMLFormElement {
             win.pipeline(), load_data)).unwrap();
     }
 
+    /// https://html.spec.whatwg.org/multipage/#constructing-the-form-data-set
+    /// Steps range from 1 to 3
     fn get_unclean_dataset(&self, submitter: Option<FormSubmitter>) -> Vec<FormDatum> {
         let node = self.upcast::<Node>();
         // TODO: This is an incorrect way of getting controls owned
         //       by the form, but good enough until html5ever lands
+        // Step 1-2
         node.traverse_preorder().filter_map(|child| {
+            // Step 3.1: The field element is disabled.
             match child.downcast::<Element>() {
                 Some(el) if !el.get_disabled_state() => (),
                 _ => return None,
             }
 
+            // Step 3.1: The field element has a datalist element ancestor.
             if child.ancestors()
                     .any(|a| Root::downcast::<HTMLDataListElement>(a).is_some()) {
                 return None;
@@ -238,6 +243,7 @@ impl HTMLFormElement {
                     match element {
                         HTMLElementTypeId::HTMLInputElement => {
                             let input = child.downcast::<HTMLInputElement>().unwrap();
+                            // Step 3.2-3.7
                             input.get_form_datum(submitter)
                         }
                         HTMLElementTypeId::HTMLButtonElement |
@@ -257,9 +263,9 @@ impl HTMLFormElement {
         //       https://html.spec.whatwg.org/multipage/#the-directionality
     }
 
+    /// https://html.spec.whatwg.org/multipage/#constructing-the-form-data-set
     pub fn get_form_dataset(&self, submitter: Option<FormSubmitter>) -> Vec<FormDatum> {
         fn clean_crlf(s: &str) -> DOMString {
-            // https://html.spec.whatwg.org/multipage/#constructing-the-form-data-set
             // Step 4
             let mut buf = "".to_owned();
             let mut prev = ' ';
@@ -290,8 +296,8 @@ impl HTMLFormElement {
             DOMString::from(buf)
         }
 
+        // Step 1-3
         let mut ret = self.get_unclean_dataset(submitter);
-        // https://html.spec.whatwg.org/multipage/#constructing-the-form-data-set
         // Step 4
         for datum in &mut ret {
             match &*datum.ty {
@@ -302,6 +308,7 @@ impl HTMLFormElement {
                 }
             }
         };
+        // Step 5
         ret
     }
 
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 13af224bef1..092e963840b 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -423,8 +423,12 @@ impl HTMLInputElement {
         }
     }
 
+    /// https://html.spec.whatwg.org/multipage/#constructing-the-form-data-set
+    /// Steps range from 3.1 to 3.7 which related to the HTMLInputElement
     pub fn get_form_datum(&self, submitter: Option<FormSubmitter>) -> Option<FormDatum> {
+        // Step 3.2
         let ty = self.type_();
+        // Step 3.4
         let name = self.Name();
         let is_submitter = match submitter {
             Some(FormSubmitter::InputElement(s)) => {
@@ -434,21 +438,22 @@ impl HTMLInputElement {
         };
 
         match ty {
+            // Step 3.1: it's a button but it is not submitter.
             atom!("submit") | atom!("button") | atom!("reset") if !is_submitter => return None,
-            atom!("radio") | atom!("checkbox") => {
-                if !self.Checked() || name.is_empty() {
-                    return None;
-                }
+            // Step 3.1: it's the "Checkbox" or "Radio Button" and whose checkedness is false.
+            atom!("radio") | atom!("checkbox") => if !self.Checked() || name.is_empty() {
+                return None;
             },
             atom!("image") | atom!("file") => return None, // Unimplemented
-            _ => {
-                if name.is_empty() {
-                    return None;
-                }
+            // Step 3.1: it's not the "Image Button" and doesn't have a name attribute.
+            _ => if name.is_empty() {
+                return None;
             }
+
         }
 
         let mut value = self.Value();
+        // Step 3.6
         if ty == atom!("radio") || ty == atom!("checkbox") {
             if value.is_empty() {
                 value = DOMString::from("on");