ESLint: Prefer arrow callbacks (autofix) in mediawiki.widgets

Change-Id: Ic07010e5219b04b3b2b156468272d8df5dce233b

32 files changed, 131 insertions, 194 deletions

diff --git a/resources/src/mediawiki.widgets.datetime/CalendarWidget.js b/resources/src/mediawiki.widgets.datetime/CalendarWidget.js
index 2c48bf9ad4ee..7b6d69b9ab21 100644
--- a/resources/src/mediawiki.widgets.datetime/CalendarWidget.js
+++ b/resources/src/mediawiki.widgets.datetime/CalendarWidget.js
@@ -218,9 +218,7 @@
 		if ( dates instanceof Date ) {
 			dates = [ dates ];
 		} else if ( Array.isArray( dates ) ) {
-			dates = dates.filter( function ( dt ) {
-				return dt instanceof Date;
-			} );
+			dates = dates.filter( ( dt ) => dt instanceof Date );
 			dates.sort();
 		} else {
 			dates = [];
diff --git a/resources/src/mediawiki.widgets.datetime/DateTimeFormatter.js b/resources/src/mediawiki.widgets.datetime/DateTimeFormatter.js
index 0fbd01801d9d..44e1cff9eb00 100644
--- a/resources/src/mediawiki.widgets.datetime/DateTimeFormatter.js
+++ b/resources/src/mediawiki.widgets.datetime/DateTimeFormatter.js
@@ -345,9 +345,7 @@
 						};
 						spec.size = Math.max.apply(
 							// eslint-disable-next-line no-jquery/no-map-util
-							null, $.map( spec.values, function ( v ) {
-								return v.length;
-							} )
+							null, $.map( spec.values, ( v ) => v.length )
 						);
 						return spec;
 				}
diff --git a/resources/src/mediawiki.widgets.datetime/DiscordianDateTimeFormatter.js b/resources/src/mediawiki.widgets.datetime/DiscordianDateTimeFormatter.js
index 0447518b772b..8f920332ffa1 100644
--- a/resources/src/mediawiki.widgets.datetime/DiscordianDateTimeFormatter.js
+++ b/resources/src/mediawiki.widgets.datetime/DiscordianDateTimeFormatter.js
@@ -198,9 +198,7 @@
 			if ( spec.values ) {
 				spec.size = Math.max.apply(
 					// eslint-disable-next-line no-jquery/no-map-util
-					null, $.map( spec.values, function ( v ) {
-						return v.length;
-					} )
+					null, $.map( spec.values, ( v ) => v.length )
 				);
 			}
 		}
diff --git a/resources/src/mediawiki.widgets.datetime/ProlepticGregorianDateTimeFormatter.js b/resources/src/mediawiki.widgets.datetime/ProlepticGregorianDateTimeFormatter.js
index df06028c31e3..a0dd35a752cb 100644
--- a/resources/src/mediawiki.widgets.datetime/ProlepticGregorianDateTimeFormatter.js
+++ b/resources/src/mediawiki.widgets.datetime/ProlepticGregorianDateTimeFormatter.js
@@ -39,28 +39,28 @@
 		if ( config.fullMonthNames && !config.shortMonthNames ) {
 			config.shortMonthNames = {};
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( config.fullMonthNames, function ( k, v ) {
+			$.each( config.fullMonthNames, ( k, v ) => {
 				config.shortMonthNames[ k ] = v.slice( 0, 3 );
 			} );
 		}
 		if ( config.shortDayNames && !config.dayLetters ) {
 			config.dayLetters = [];
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( config.shortDayNames, function ( k, v ) {
+			$.each( config.shortDayNames, ( k, v ) => {
 				config.dayLetters[ k ] = v.slice( 0, 1 );
 			} );
 		}
 		if ( config.fullDayNames && !config.dayLetters ) {
 			config.dayLetters = [];
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( config.fullDayNames, function ( k, v ) {
+			$.each( config.fullDayNames, ( k, v ) => {
 				config.dayLetters[ k ] = v.slice( 0, 1 );
 			} );
 		}
 		if ( config.fullDayNames && !config.shortDayNames ) {
 			config.shortDayNames = {};
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( config.fullDayNames, function ( k, v ) {
+			$.each( config.fullDayNames, ( k, v ) => {
 				config.shortDayNames[ k ] = v.slice( 0, 3 );
 			} );
 		}
@@ -173,30 +173,30 @@
 		if ( this.fullMonthNames && !this.shortMonthNames ) {
 			this.shortMonthNames = {};
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( this.fullMonthNames, function ( k, v ) {
+			$.each( this.fullMonthNames, ( k, v ) => {
 				this.shortMonthNames[ k ] = v.slice( 0, 3 );
-			}.bind( this ) );
+			} );
 		}
 		if ( this.shortDayNames && !this.dayLetters ) {
 			this.dayLetters = [];
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( this.shortDayNames, function ( k, v ) {
+			$.each( this.shortDayNames, ( k, v ) => {
 				this.dayLetters[ k ] = v.slice( 0, 1 );
-			}.bind( this ) );
+			} );
 		}
 		if ( this.fullDayNames && !this.dayLetters ) {
 			this.dayLetters = [];
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( this.fullDayNames, function ( k, v ) {
+			$.each( this.fullDayNames, ( k, v ) => {
 				this.dayLetters[ k ] = v.slice( 0, 1 );
-			}.bind( this ) );
+			} );
 		}
 		if ( this.fullDayNames && !this.shortDayNames ) {
 			this.shortDayNames = {};
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( this.fullDayNames, function ( k, v ) {
+			$.each( this.fullDayNames, ( k, v ) => {
 				this.shortDayNames[ k ] = v.slice( 0, 3 );
-			}.bind( this ) );
+			} );
 		}
 
 		if ( !this.fullMonthNames ) {
@@ -413,9 +413,7 @@
 			if ( spec.values ) {
 				spec.size = Math.max.apply(
 					// eslint-disable-next-line no-jquery/no-map-util
-					null, $.map( spec.values, function ( v ) {
-						return v.length;
-					} )
+					null, $.map( spec.values, ( v ) => v.length )
 				);
 			}
 		}
diff --git a/resources/src/mediawiki.widgets.visibleLengthLimit/mediawiki.widgets.visibleLengthLimit.js b/resources/src/mediawiki.widgets.visibleLengthLimit/mediawiki.widgets.visibleLengthLimit.js
index 1d789123daaa..206430930b9c 100644
--- a/resources/src/mediawiki.widgets.visibleLengthLimit/mediawiki.widgets.visibleLengthLimit.js
+++ b/resources/src/mediawiki.widgets.visibleLengthLimit/mediawiki.widgets.visibleLengthLimit.js
@@ -62,7 +62,7 @@
 		internalVisibleLimit( lengthLimiter, textInputWidget, limit, filterFunction );
 
 		// Keep the remaining counter in sync when reason list changed
-		dropdownInputWidget.on( 'change', function () {
+		dropdownInputWidget.on( 'change', () => {
 			textInputWidget.emit( 'change' );
 		} );
 	}
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsProvider.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsProvider.js
index 42b07d1958e0..e03c2d8077df 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsProvider.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsProvider.js
@@ -60,7 +60,7 @@
 			allParams = $.extend( {}, this.getStaticParams(), this.getUserParams() );
 
 		const xhr = $.getJSON( this.getAPIurl(), allParams )
-			.done( function ( data ) {
+			.done( ( data ) => {
 				if ( Array.isArray( data ) && data.length ) {
 					deferred.resolve( data );
 				} else {
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsQueue.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsQueue.js
index bdc37615db1f..d3ed08dc0970 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsQueue.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.APIResultsQueue.js
@@ -69,16 +69,14 @@
 		if ( this.queue.length < howMany + this.threshold ) {
 			// Call for more results
 			fetchingPromise = this.queryProviders( howMany + this.threshold )
-				.then( function ( items ) {
+				.then( ( items ) => {
 					// Add to the queue
 					me.queue = me.queue.concat.apply( me.queue, items );
 				} );
 		}
 
 		return $.when( fetchingPromise )
-			.then( function () {
-				return me.queue.splice( 0, howMany );
-			} );
+			.then( () => me.queue.splice( 0, howMany ) );
 
 	};
 
@@ -95,7 +93,7 @@
 
 		// Make sure there are resources set up
 		return this.setup()
-			.then( function () {
+			.then( () => {
 				// Abort previous requests
 				for ( let i = 0, iLen = queue.providerPromises.length; i < iLen; i++ ) {
 					queue.providerPromises[ i ].abort();
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceProvider.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceProvider.js
index f744421b5c74..e626f6d9cc87 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceProvider.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceProvider.js
@@ -80,7 +80,7 @@
 				action: 'query',
 				meta: 'siteinfo'
 			} )
-				.then( function ( data ) {
+				.then( ( data ) => {
 					provider.setImageSizes( data.query.general.imagelimits || [] );
 					provider.setThumbSizes( data.query.general.thumblimits || [] );
 					provider.setUserParams( {
@@ -106,7 +106,7 @@
 		const provider = this;
 
 		return this.loadSiteInfo()
-			.then( function () {
+			.then( () => {
 				if ( aborted ) {
 					return $.Deferred().reject();
 				}
@@ -114,7 +114,7 @@
 				return xhr;
 			} )
 			.then(
-				function ( results ) {
+				( results ) => {
 					if ( !results || results.length === 0 ) {
 						provider.toggleDepleted( true );
 						return [];
@@ -122,7 +122,7 @@
 					return results;
 				},
 				// Process failed, return an empty promise
-				function () {
+				() => {
 					provider.toggleDepleted( true );
 					return $.Deferred().resolve( [] );
 				}
@@ -180,7 +180,7 @@
 		const api = this.isLocal ? new mw.Api() : new mw.ForeignApi( this.getAPIurl(), { anonymous: true } );
 		const xhr = api.get( $.extend( {}, this.getStaticParams(), this.getUserParams(), this.getContinueData( howMany ) ) );
 		return xhr
-			.then( function ( data ) {
+			.then( ( data ) => {
 				const results = [];
 
 				if ( data.error ) {
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceQueue.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceQueue.js
index 45d101080b69..3fe970353d8a 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceQueue.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaResourceQueue.js
@@ -46,12 +46,8 @@
 				action: 'query',
 				meta: 'filerepoinfo'
 			} ).then(
-				function ( resp ) {
-					return resp.query && resp.query.repos || defaultSource;
-				},
-				function () {
-					return $.Deferred().resolve( defaultSource );
-				}
+				( resp ) => resp.query && resp.query.repos || defaultSource,
+				() => $.Deferred().resolve( defaultSource )
 			);
 		}
 
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchProvider.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchProvider.js
index c467bb810c45..6dda6adb51f6 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchProvider.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchProvider.js
@@ -57,9 +57,7 @@
 	 * @inheritdoc
 	 */
 	mw.widgets.MediaSearchProvider.prototype.sort = function ( results ) {
-		return results.sort( function ( a, b ) {
-			return a.index - b.index;
-		} );
+		return results.sort( ( a, b ) => a.index - b.index );
 	};
 
 	/**
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchQueue.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchQueue.js
index bb273d5c89ce..60c585901c89 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchQueue.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchQueue.js
@@ -37,7 +37,7 @@
 	mw.widgets.MediaSearchQueue.prototype.setup = function () {
 		const queue = this;
 
-		return this.getFileRepos().then( function ( sources ) {
+		return this.getFileRepos().then( ( sources ) => {
 			if ( queue.providers.length === 0 ) {
 				// Set up the providers
 				for ( let i = 0, len = sources.length; i < len; i++ ) {
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchWidget.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchWidget.js
index 2819c66a1eed..d06bd1c9e1d8 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchWidget.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaSearchWidget.js
@@ -174,7 +174,7 @@
 		search.noItemsMessage.toggle( false );
 
 		this.currentQueue.get( this.constructor.static.limit )
-			.then( function ( items ) {
+			.then( ( items ) => {
 				if ( items.length > 0 ) {
 					search.processQueueResults( items );
 					search.currentItemCache = search.currentItemCache.concat( items );
@@ -392,7 +392,7 @@
 
 		// Add method to a queue; this queue will only run when the widget
 		// is visible
-		this.layoutQueue.push( function () {
+		this.layoutQueue.push( () => {
 			const maxRowWidth = search.results.$element.width() - 15;
 
 			// Go over the added items
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsProvider.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsProvider.js
index 6b4db30286a2..bd4248adcc02 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsProvider.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsProvider.js
@@ -57,11 +57,10 @@
 	 * @inheritdoc
 	 */
 	mw.widgets.MediaUserUploadsProvider.prototype.sort = function ( results ) {
-		return results.sort( function ( a, b ) {
+		return results.sort(
 			// timestamps are strings
-			return a.timestamp < b.timestamp ? 1 :
-				( a.timestamp === b.timestamp ? 0 : -1 );
-		} );
+			( a, b ) => a.timestamp < b.timestamp ? 1 : ( a.timestamp === b.timestamp ? 0 : -1 )
+		);
 	};
 
 	/**
diff --git a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsQueue.js b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsQueue.js
index 697394df6e28..72e7afb4f8a7 100644
--- a/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsQueue.js
+++ b/resources/src/mediawiki.widgets/MediaSearch/mw.widgets.MediaUserUploadsQueue.js
@@ -41,7 +41,7 @@
 	mw.widgets.MediaUserUploadsQueue.prototype.setup = function () {
 		const queue = this;
 
-		return this.getFileRepos().then( function ( sources ) {
+		return this.getFileRepos().then( ( sources ) => {
 			if ( queue.providers.length === 0 ) {
 				// Set up the providers
 				for ( let i = 0, len = sources.length; i < len; i++ ) {
diff --git a/resources/src/mediawiki.widgets/Table/mw.widgets.RowWidget.js b/resources/src/mediawiki.widgets/Table/mw.widgets.RowWidget.js
index 879593d63c1c..bad8487c1381 100644
--- a/resources/src/mediawiki.widgets/Table/mw.widgets.RowWidget.js
+++ b/resources/src/mediawiki.widgets/Table/mw.widgets.RowWidget.js
@@ -304,7 +304,7 @@ mw.widgets.RowWidget.prototype.onCellChange = function ( input, value ) {
 	// Right now, the table can't know if it's valid or not because the events
 	// don't get passed through.
 	const self = this;
-	input.getValidity().done( function () {
+	input.getValidity().done( () => {
 		self.model.setValue( input.getData(), value );
 	} );
 };
@@ -334,7 +334,7 @@ mw.widgets.RowWidget.prototype.setDisabled = function ( disabled ) {
 		this.deleteButton.setDisabled( disabled );
 	}
 
-	this.getItems().forEach( function ( cell ) {
+	this.getItems().forEach( ( cell ) => {
 		cell.setDisabled( disabled );
 	} );
 };
diff --git a/resources/src/mediawiki.widgets/Table/mw.widgets.TableWidget.js b/resources/src/mediawiki.widgets/Table/mw.widgets.TableWidget.js
index cbc75d9d3df9..0a76c3d40d58 100644
--- a/resources/src/mediawiki.widgets/Table/mw.widgets.TableWidget.js
+++ b/resources/src/mediawiki.widgets/Table/mw.widgets.TableWidget.js
@@ -543,12 +543,12 @@ mw.widgets.TableWidget.prototype.setDisabled = function ( disabled ) {
 		return;
 	}
 
-	this.getItems().forEach( function ( row ) {
+	this.getItems().forEach( ( row ) => {
 		row.setDisabled( disabled );
 	} );
 
 	if ( this.model.getTableProperties().allowRowInsertion ) {
-		this.insertionRow.getItems().forEach( function ( row ) {
+		this.insertionRow.getItems().forEach( ( row ) => {
 			row.setDisabled( disabled );
 		} );
 	}
diff --git a/resources/src/mediawiki.widgets/mw.widgets.CalendarWidget.js b/resources/src/mediawiki.widgets/mw.widgets.CalendarWidget.js
index 87a99feaee70..f4468f763ead 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.CalendarWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.CalendarWidget.js
@@ -330,7 +330,7 @@
 			} else if ( fade === 'next' || fade === 'down' ) {
 				this.$body.insertAfter( this.$oldBody );
 			}
-			setTimeout( function () {
+			setTimeout( () => {
 				// The following classes are used here:
 				// * mw-widget-calendarWidget-body-wrapper-fade-up
 				// * mw-widget-calendarWidget-body-wrapper-fade-down
diff --git a/resources/src/mediawiki.widgets/mw.widgets.CategoryMultiselectWidget.js b/resources/src/mediawiki.widgets/mw.widgets.CategoryMultiselectWidget.js
index 1698fb196505..7e7b8b0a6ca1 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.CategoryMultiselectWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.CategoryMultiselectWidget.js
@@ -88,7 +88,7 @@
 	 */
 	mw.widgets.CategoryMultiselectWidget.prototype.updateMenuItems = function () {
 		this.getMenu().clearItems();
-		this.getNewMenuItems( this.input.$input.val() ).then( function ( items ) {
+		this.getNewMenuItems( this.input.$input.val() ).then( ( items ) => {
 			const menu = this.getMenu();
 
 			// Never show the menu if the input lost focus in the meantime
@@ -97,25 +97,19 @@
 			}
 
 			// Array of strings of the data of OO.ui.MenuOptionsWidgets
-			const existingItems = menu.getItems().map( function ( item ) {
-				return item.data;
-			} );
+			const existingItems = menu.getItems().map( ( item ) => item.data );
 
 			// Remove if items' data already exists
-			let filteredItems = items.filter( function ( item ) {
-				return existingItems.indexOf( item ) === -1;
-			} );
+			let filteredItems = items.filter( ( item ) => existingItems.indexOf( item ) === -1 );
 
 			// Map to an array of OO.ui.MenuOptionWidgets
-			filteredItems = filteredItems.map( function ( item ) {
-				return new OO.ui.MenuOptionWidget( {
-					data: item,
-					label: item
-				} );
-			} );
+			filteredItems = filteredItems.map( ( item ) => new OO.ui.MenuOptionWidget( {
+				data: item,
+				label: item
+			} ) );
 
 			menu.addItems( filteredItems ).toggle( true );
-		}.bind( this ) );
+		} );
 	};
 
 	/**
@@ -152,27 +146,19 @@
 
 		this.pushPending();
 
-		$.when.apply( $, promises ).done( function ( ...dataSets ) {
+		$.when.apply( $, promises ).done( ( ...dataSets ) => {
 			// Flatten array
 			const allData = Array.prototype.concat.apply( [], dataSets );
 
 			const categoryNames = allData
 				// Remove duplicates
-				.filter( function ( value, index, self ) {
-					return self.indexOf( value ) === index;
-				} )
+				.filter( ( value, index, self ) => self.indexOf( value ) === index )
 				// Get Title objects
-				.map( function ( name ) {
-					return mw.Title.newFromText( name );
-				} )
+				.map( ( name ) => mw.Title.newFromText( name ) )
 				// Keep only titles from 'Category' namespace
-				.filter( function ( title ) {
-					return title && title.getNamespaceId() === NS_CATEGORY;
-				} )
+				.filter( ( title ) => title && title.getNamespaceId() === NS_CATEGORY )
 				// Convert back to strings, strip 'Category:' prefix
-				.map( function ( title ) {
-					return title.getMainText();
-				} );
+				.map( ( title ) => title.getMainText() );
 
 			deferred.resolve( categoryNames );
 
@@ -229,9 +215,7 @@
 		const searchTypeEnumCount = Object.keys( mw.widgets.CategoryMultiselectWidget.SearchType ).length;
 
 		// Check if all values are in the SearchType enum
-		validSearchTypes = this.searchTypes.every( function ( searchType ) {
-			return searchType > -1 && searchType < searchTypeEnumCount;
-		} );
+		validSearchTypes = this.searchTypes.every( ( searchType ) => searchType > -1 && searchType < searchTypeEnumCount );
 
 		if ( validSearchTypes === false ) {
 			throw new Error( 'Unknown searchType in searchTypes' );
@@ -292,7 +276,7 @@
 					namespace: NS_CATEGORY,
 					limit: this.limit,
 					search: input
-				} ).done( function ( res ) {
+				} ).done( ( res ) => {
 					const categories = res[ 1 ];
 					deferred.resolve( categories );
 				} ).fail( deferred.reject.bind( deferred ) );
@@ -307,10 +291,8 @@
 					aplimit: this.limit,
 					apfrom: input,
 					apprefix: input
-				} ).done( function ( res ) {
-					const categories = res.query.allpages.map( function ( page ) {
-						return page.title;
-					} );
+				} ).done( ( res ) => {
+					const categories = res.query.allpages.map( ( page ) => page.title );
 					deferred.resolve( categories );
 				} ).fail( deferred.reject.bind( deferred ) );
 				break;
@@ -326,10 +308,10 @@
 					action: 'query',
 					prop: 'info',
 					titles: 'Category:' + input
-				} ).done( function ( res ) {
+				} ).done( ( res ) => {
 					const categories = [];
 
-					res.query.pages.forEach( function ( page ) {
+					res.query.pages.forEach( ( page ) => {
 						if ( !page.missing ) {
 							categories.push( page.title );
 						}
@@ -352,10 +334,8 @@
 					cmtype: 'subcat',
 					cmlimit: this.limit,
 					cmtitle: 'Category:' + input
-				} ).done( function ( res ) {
-					const categories = res.query.categorymembers.map( function ( category ) {
-						return category.title;
-					} );
+				} ).done( ( res ) => {
+					const categories = res.query.categorymembers.map( ( category ) => category.title );
 					deferred.resolve( categories );
 				} ).fail( deferred.reject.bind( deferred ) );
 				break;
@@ -372,14 +352,12 @@
 					prop: 'categories',
 					cllimit: this.limit,
 					titles: 'Category:' + input
-				} ).done( function ( res ) {
+				} ).done( ( res ) => {
 					const categories = [];
 
-					res.query.pages.forEach( function ( page ) {
+					res.query.pages.forEach( ( page ) => {
 						if ( !page.missing && Array.isArray( page.categories ) ) {
-							categories.push.apply( categories, page.categories.map( function ( category ) {
-								return category.title;
-							} ) );
+							categories.push.apply( categories, page.categories.map( ( category ) => category.title ) );
 						}
 					} );
 
diff --git a/resources/src/mediawiki.widgets/mw.widgets.CategoryTagItemWidget.js b/resources/src/mediawiki.widgets/mw.widgets.CategoryTagItemWidget.js
index 9f760302149e..62a3c16d66b0 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.CategoryTagItemWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.CategoryTagItemWidget.js
@@ -30,7 +30,7 @@
 		const cache = this;
 		if ( this.currentRequest ) {
 			// Don't fire off a million requests at the same time
-			this.currentRequest.always( function () {
+			this.currentRequest.always( () => {
 				cache.currentRequest = null;
 				cache.processExistenceCheckQueueDebounced();
 			} );
@@ -38,7 +38,7 @@
 		}
 		const queue = this.existenceCheckQueue;
 		this.existenceCheckQueue = {};
-		const titles = Object.keys( queue ).filter( function ( title ) {
+		const titles = Object.keys( queue ).filter( ( title ) => {
 			if ( hasOwn.call( cache.existenceCache, title ) ) {
 				queue[ title ].resolve( cache.existenceCache[ title ] );
 			}
@@ -52,17 +52,17 @@
 			action: 'query',
 			prop: [ 'info' ],
 			titles: titles
-		} ).done( function ( response ) {
+		} ).done( ( response ) => {
 			const
 				normalized = {},
 				pages = {};
-			( response.query.normalized || [] ).forEach( function ( data ) {
+			( response.query.normalized || [] ).forEach( ( data ) => {
 				normalized[ data.fromencoded ? decodeURIComponent( data.from ) : data.from ] = data.to;
 			} );
-			response.query.pages.forEach( function ( page ) {
+			response.query.pages.forEach( ( page ) => {
 				pages[ page.title ] = !page.missing;
 			} );
-			titles.forEach( function ( title ) {
+			titles.forEach( ( title ) => {
 				let normalizedTitle = title;
 				while ( hasOwn.call( normalized, normalizedTitle ) ) {
 					normalizedTitle = normalized[ normalizedTitle ];
@@ -138,7 +138,7 @@
 		this.$link = $( '<a>' )
 			.text( this.label )
 			.attr( 'target', '_blank' )
-			.on( 'click', function ( e ) {
+			.on( 'click', ( e ) => {
 				// TagMultiselectWidget really wants to prevent you from clicking the link, don't let it
 				e.stopPropagation();
 			} );
@@ -154,7 +154,7 @@
 		}
 		this.constructor.static.pageExistenceCaches[ this.apiUrl ]
 			.checkPageExistence( new ForeignTitle( this.title.getPrefixedText() ) )
-			.done( function ( exists ) {
+			.done( ( exists ) => {
 				widget.setMissing( !exists );
 			} );
 	};
diff --git a/resources/src/mediawiki.widgets/mw.widgets.CheckMatrixWidget.js b/resources/src/mediawiki.widgets/mw.widgets.CheckMatrixWidget.js
index b8e85210d449..afe99fbe6539 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.CheckMatrixWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.CheckMatrixWidget.js
@@ -44,7 +44,7 @@
 
 		// Iterate over the columns object (ignore the value)
 		// eslint-disable-next-line no-jquery/no-each-util
-		$.each( this.columns, function ( columnLabel ) {
+		$.each( this.columns, ( columnLabel ) => {
 			$headRow.append( $( '<th>' ).html( columnLabel ) );
 		} );
 		const $thead = $( '<thead>' );
@@ -53,7 +53,7 @@
 		const $tbody = $( '<tbody>' );
 		// Build table
 		// eslint-disable-next-line no-jquery/no-each-util
-		$.each( this.rows, function ( rowLabel, rowTag ) {
+		$.each( this.rows, ( rowLabel, rowTag ) => {
 			const $row = $( '<tr>' ),
 				labelField = new OO.ui.FieldLayout(
 					new OO.ui.Widget(), // Empty widget, since we don't have the checkboxes here
@@ -70,7 +70,7 @@
 
 			// Columns
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( widget.columns, function ( columnLabel, columnTag ) {
+			$.each( widget.columns, ( columnLabel, columnTag ) => {
 				const thisTag = columnTag + '-' + rowTag,
 					checkbox = new OO.ui.CheckboxInputWidget( {
 						value: thisTag,
@@ -149,7 +149,7 @@
 		if ( this.checkboxes ) {
 			// Propagate to all checkboxes and update their disabled state
 			// eslint-disable-next-line no-jquery/no-each-util
-			$.each( this.checkboxes, function ( name, checkbox ) {
+			$.each( this.checkboxes, ( name, checkbox ) => {
 				checkbox.setDisabled( widget.isTagDisabled( name ) );
 			} );
 		}
diff --git a/resources/src/mediawiki.widgets/mw.widgets.DateInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.DateInputWidget.js
index 00952e0b2bd0..327277fc7131 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.DateInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.DateInputWidget.js
@@ -203,7 +203,7 @@
 			$overlay.append( this.calendar.$element );
 
 			// The text input and calendar are not in DOM order, so fix up focus transitions.
-			this.textInput.$input.on( 'keydown', function ( e ) {
+			this.textInput.$input.on( 'keydown', ( e ) => {
 				if ( e.which === OO.ui.Keys.TAB ) {
 					if ( e.shiftKey ) {
 						// Tabbing backward from text input: normal browser behavior
@@ -213,8 +213,8 @@
 						return false;
 					}
 				}
-			}.bind( this ) );
-			this.calendar.$element.on( 'keydown', function ( e ) {
+			} );
+			this.calendar.$element.on( 'keydown', ( e ) => {
 				if ( e.which === OO.ui.Keys.TAB ) {
 					if ( e.shiftKey ) {
 						// Tabbing backward from calendar: just focus the text input
@@ -226,7 +226,7 @@
 						this.textInput.$input.trigger( 'focus' );
 					}
 				}
-			}.bind( this ) );
+			} );
 		}
 
 		// Set handle label and hide stuff
@@ -342,7 +342,7 @@
 	 */
 	mw.widgets.DateInputWidget.prototype.onBlur = function () {
 		const widget = this;
-		setTimeout( function () {
+		setTimeout( () => {
 			const $focussed = $( ':focus' );
 			// Deactivate unless the focus moved to something else inside this widget
 			if (
@@ -687,9 +687,9 @@
 		if ( isValid !== undefined ) {
 			setFlag( isValid );
 		} else {
-			this.getValidity().then( function () {
+			this.getValidity().then( () => {
 				setFlag( true );
-			}, function () {
+			}, () => {
 				setFlag( false );
 			} );
 		}
diff --git a/resources/src/mediawiki.widgets/mw.widgets.ExpiryInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.ExpiryInputWidget.js
index 00390ae93c76..448d634de060 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.ExpiryInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.ExpiryInputWidget.js
@@ -56,7 +56,7 @@
 		// Events
 
 		// Toggle the visible inputs.
-		this.inputSwitch.on( 'choose', function ( event ) {
+		this.inputSwitch.on( 'choose', ( event ) => {
 			switch ( event.getData() ) {
 				case 'date':
 					this.dateTimeField.toggle( true );
@@ -67,11 +67,11 @@
 					this.relativeField.toggle( true );
 					break;
 			}
-		}.bind( this ) );
+		} );
 
 		// When the date time field update, update the relative
 		// field.
-		this.dateTimeField.on( 'change', function ( value ) {
+		this.dateTimeField.on( 'change', ( value ) => {
 			// Do not alter the visible input.
 			if ( this.relativeField.isVisible() ) {
 				return;
@@ -92,11 +92,11 @@
 
 			// Set the relative field value. The field only accepts English strings.
 			this.relativeField.setValue( datetime.utc().locale( 'en' ).format( RFC2822 ) );
-		}.bind( this ) );
+		} );
 
 		// When the relative field update, update the date time field if it's a
 		// value that moment understands.
-		this.relativeField.on( 'change', function ( event ) {
+		this.relativeField.on( 'change', ( event ) => {
 			// Emit a change event for this widget.
 			this.emit( 'change', event );
 
@@ -114,7 +114,7 @@
 			} else {
 				this.dateTimeField.setValue( undefined );
 			}
-		}.bind( this ) );
+		} );
 
 		// Initialization
 		this.$element
diff --git a/resources/src/mediawiki.widgets/mw.widgets.NamespaceInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.NamespaceInputWidget.js
index 0515d7a78a69..d4ca8120ed60 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.NamespaceInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.NamespaceInputWidget.js
@@ -59,7 +59,7 @@
 			mw.config.get( 'wgFormattedNamespaces' );
 
 		// eslint-disable-next-line no-jquery/no-map-util
-		const options = $.map( namespaces, function ( name, ns ) {
+		const options = $.map( namespaces, ( name, ns ) => {
 			if ( ns < mainNamespace || exclude.indexOf( Number( ns ) ) !== -1 ) {
 				return null; // skip
 			}
@@ -68,10 +68,10 @@
 				name = mw.msg( 'blanknamespace' );
 			}
 			return { data: ns, label: name };
-		} ).sort( function ( a, b ) {
+		} ).sort(
 			// wgFormattedNamespaces is an object, and so technically doesn't have to be ordered
-			return a.data - b.data;
-		} );
+			( a, b ) => a.data - b.data
+		);
 
 		if ( config.includeAllValue !== null && config.includeAllValue !== undefined ) {
 			options.unshift( {
diff --git a/resources/src/mediawiki.widgets/mw.widgets.NamespacesMultiselectWidget.js b/resources/src/mediawiki.widgets/mw.widgets.NamespacesMultiselectWidget.js
index ffe7264114d3..a14909b33c7c 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.NamespacesMultiselectWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.NamespacesMultiselectWidget.js
@@ -42,12 +42,10 @@
 			},
 			config,
 			{
-				selected: config && config.selected ? config.selected.map( function ( id ) {
-					return {
-						data: id,
-						label: namespaces[ id ]
-					};
-				} ) : undefined
+				selected: config && config.selected ? config.selected.map( ( id ) => ( {
+					data: id,
+					label: namespaces[ id ]
+				} ) ) : undefined
 			}
 		) );
 
@@ -65,17 +63,13 @@
 				.appendTo( this.$element );
 			// Update with preset values
 			// Set the default value (it might be different from just being empty)
-			this.$hiddenInput.prop( 'defaultValue', this.getItems().map( function ( item ) {
-				return item.getData();
-			} ).join( '\n' ) );
-			this.on( 'change', function ( items ) {
-				this.$hiddenInput.val( items.map( function ( item ) {
-					return item.getData();
-				} ).join( '\n' ) );
+			this.$hiddenInput.prop( 'defaultValue', this.getItems().map( ( item ) => item.getData() ).join( '\n' ) );
+			this.on( 'change', ( items ) => {
+				this.$hiddenInput.val( items.map( ( item ) => item.getData() ).join( '\n' ) );
 				// Trigger a 'change' event as if a user edited the text
 				// (it is not triggered when changing the value from JS code).
 				this.$hiddenInput.trigger( 'change' );
-			}.bind( this ) );
+			} );
 		}
 	};
 
diff --git a/resources/src/mediawiki.widgets/mw.widgets.SearchInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.SearchInputWidget.js
index a91d9dbe5adf..952f3f6528af 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.SearchInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.SearchInputWidget.js
@@ -51,7 +51,7 @@
 		}
 		this.setLookupsDisabled( !this.suggestions );
 
-		$form.on( 'submit', function () {
+		$form.on( 'submit', () => {
 			mw.track( 'mw.widgets.SearchInputWidget', {
 				action: 'submit-form',
 				numberOfResults: this.lastLookupItems.length,
@@ -61,7 +61,7 @@
 					this.$input.val()
 				)
 			} );
-		}.bind( this ) );
+		} );
 
 		this.connect( this, {
 			change: 'onChange'
@@ -153,10 +153,10 @@
 		} );
 
 		// reuse the searchSuggest function from mw.searchSuggest
-		const promise = mw.searchSuggest.request( api, this.getQueryValue(), function () {}, this.limit, this.getNamespace() );
+		const promise = mw.searchSuggest.request( api, this.getQueryValue(), () => {}, this.limit, this.getNamespace() );
 
 		// tracking purposes
-		promise.done( function ( data, jqXHR ) {
+		promise.done( ( data, jqXHR ) => {
 			self.requestType = jqXHR.getResponseHeader( 'X-OpenSearch-Type' );
 			self.searchId = jqXHR.getResponseHeader( 'X-Search-ID' );
 		} );
@@ -195,7 +195,7 @@
 			self = this;
 
 		// eslint-disable-next-line no-jquery/no-each-util
-		$.each( titles, function ( i, result ) {
+		$.each( titles, ( i, result ) => {
 			items.push( new mw.widgets.TitleOptionWidget(
 				self.getOptionWidgetData(
 					result,
@@ -245,9 +245,7 @@
 			this, arguments
 		);
 
-		this.lastLookupItems = items.map( function ( item ) {
-			return item.data;
-		} );
+		this.lastLookupItems = items.map( ( item ) => item.data );
 
 		return items;
 	};
diff --git a/resources/src/mediawiki.widgets/mw.widgets.SelectWithInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.SelectWithInputWidget.js
index 3d396555322d..5c611fca18b1 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.SelectWithInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.SelectWithInputWidget.js
@@ -54,9 +54,9 @@
 
 		// Events
 		this.dropdowninput.on( 'change', this.onChange.bind( this ) );
-		this.textinput.on( 'change', function () {
+		this.textinput.on( 'change', () => {
 			this.emit( 'change', this.getValue() );
-		}.bind( this ) );
+		} );
 
 		// Parent constructor
 		mw.widgets.SelectWithInputWidget.super.call( this, config );
diff --git a/resources/src/mediawiki.widgets/mw.widgets.TitleInputWidget.js b/resources/src/mediawiki.widgets/mw.widgets.TitleInputWidget.js
index 2cfd4b37083e..9a3a738fdd78 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.TitleInputWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.TitleInputWidget.js
@@ -135,7 +135,7 @@
 		// Parent method
 		value = mw.widgets.TitleInputWidget.super.prototype.cleanUpValue.call( this, value );
 
-		return trimByteLength( this.value, value, this.maxLength, function ( val ) {
+		return trimByteLength( this.value, value, this.maxLength, ( val ) => {
 			const title = widget.getMWTitle( val );
 			return title ? title.getMain() : val;
 		} ).newVal;
diff --git a/resources/src/mediawiki.widgets/mw.widgets.TitleOptionWidget.js b/resources/src/mediawiki.widgets/mw.widgets.TitleOptionWidget.js
index 6db6a698ec24..5e51aae682e9 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.TitleOptionWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.TitleOptionWidget.js
@@ -65,7 +65,7 @@
 		this.$label.attr( 'tabindex', '-1' );
 
 		// Allow opening the link in new tab, but not regular navigation.
-		this.$label.on( 'click', function ( e ) {
+		this.$label.on( 'click', ( e ) => {
 			// Don't interfere with special clicks (e.g. to open in new tab)
 			if ( !( e.which !== 1 || e.altKey || e.ctrlKey || e.shiftKey || e.metaKey ) ) {
 				e.preventDefault();
diff --git a/resources/src/mediawiki.widgets/mw.widgets.TitleSearchWidget.js b/resources/src/mediawiki.widgets/mw.widgets.TitleSearchWidget.js
index 1af740289099..29e772fab40f 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.TitleSearchWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.TitleSearchWidget.js
@@ -77,7 +77,7 @@
 	mw.widgets.TitleSearchWidget.prototype.onQueryChange = function () {
 		const widget = this;
 
-		this.getRequestData().done( function ( data ) {
+		this.getRequestData().done( ( data ) => {
 			if ( widget.query.isReadOnly() ) {
 				// The request object is always abortable, so just
 				// prevent the results from displaying
diff --git a/resources/src/mediawiki.widgets/mw.widgets.TitleWidget.js b/resources/src/mediawiki.widgets/mw.widgets.TitleWidget.js
index 9e771630e013..9163ce107906 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.TitleWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.TitleWidget.js
@@ -132,11 +132,7 @@
 				smaxage: 60 * 60 * 24,
 				// Workaround T97096 by setting uselang=content
 				uselang: 'content'
-			} ).then( function ( data ) {
-				return data.query.interwikimap.map( function ( interwiki ) {
-					return interwiki.prefix;
-				} );
-			} );
+			} ).then( ( data ) => data.query.interwikimap.map( ( interwiki ) => interwiki.prefix ) );
 		}
 		return cache[ key ];
 	};
@@ -165,12 +161,10 @@
 			return fragment.toLowerCase().replace( /_/g, ' ' );
 		}
 
-		return this.sectionsCache[ normalizedTitleText ].then( function ( response ) {
+		return this.sectionsCache[ normalizedTitleText ].then( ( response ) => {
 			const sections = OO.getProp( response, 'parse', 'sections' ) || [];
 			const normalizedFragmentQuery = normalizeFragment( fragmentQuery );
-			const results = sections.filter( function ( section ) {
-				return normalizeFragment( section.line ).indexOf( normalizedFragmentQuery ) !== -1;
-			} ).map( function ( section ) {
+			const results = sections.filter( ( section ) => normalizeFragment( section.line ).indexOf( normalizedFragmentQuery ) !== -1 ).map( ( section ) => {
 				const fragment = section.linkAnchor.replace( /_/g, ' ' );
 				// TODO: Make promise abortable
 				return {
@@ -184,9 +178,7 @@
 				};
 			} );
 			// Sorting also happens later, but we need to do it now before we truncate
-			results.sort( function ( a, b ) {
-				return a.index - b.index;
-			} );
+			results.sort( ( a, b ) => a.index - b.index );
 			// Fake query result
 			return {
 				query: {
@@ -223,7 +215,7 @@
 			return $.Deferred().resolve( {} ).promise( promiseAbortObject );
 		}
 
-		return this.getInterwikiPrefixesPromise().then( function ( interwikiPrefixes ) {
+		return this.getInterwikiPrefixesPromise().then( ( interwikiPrefixes ) => {
 			// Optimization: check we have any prefixes.
 			if ( interwikiPrefixes.length ) {
 				const interwiki = query.slice( 0, Math.max( 0, query.indexOf( ':' ) ) );
@@ -243,7 +235,7 @@
 			// Not a interwiki: do a prefix-search API lookup of the query.
 			const prefixSearchRequest = api.get( widget.getApiParams( query ) );
 			promiseAbortObject.abort = prefixSearchRequest.abort.bind( prefixSearchRequest ); // TODO ew
-			return prefixSearchRequest.then( function ( prefixSearchResponse ) {
+			return prefixSearchRequest.then( ( prefixSearchResponse ) => {
 				if ( !widget.showMissing ) {
 					return prefixSearchResponse;
 				}
@@ -254,7 +246,7 @@
 					titles: title ? title.getPrefixedDb() : query
 				} );
 				promiseAbortObject.abort = queryTitleRequest.abort.bind( queryTitleRequest );
-				return queryTitleRequest.then( function ( queryTitleResponse ) {
+				return queryTitleRequest.then( ( queryTitleResponse ) => {
 					// By default, return the prefix-search result.
 					const result = prefixSearchResponse;
 					if ( prefixSearchResponse.query === undefined ) {
@@ -416,9 +408,7 @@
 			}
 		}
 
-		titles.sort( function ( a, b ) {
-			return pageData[ a ].index - pageData[ b ].index;
-		} );
+		titles.sort( ( a, b ) => pageData[ a ].index - pageData[ b ].index );
 
 		// If not found, run value through mw.Title to avoid treating a match as a
 		// mismatch where normalisation would make them matching (T50476)
diff --git a/resources/src/mediawiki.widgets/mw.widgets.TitlesMultiselectWidget.js b/resources/src/mediawiki.widgets/mw.widgets.TitlesMultiselectWidget.js
index e6dea44bf0a0..e3e4eb4a263f 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.TitlesMultiselectWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.TitlesMultiselectWidget.js
@@ -64,17 +64,13 @@
 				.appendTo( this.$element );
 			// Update with preset values
 			// Set the default value (it might be different from just being empty)
-			this.$hiddenInput.prop( 'defaultValue', this.getItems().map( function ( item ) {
-				return item.getData();
-			} ).join( '\n' ) );
-			this.on( 'change', function ( items ) {
-				this.$hiddenInput.val( items.map( function ( item ) {
-					return item.getData();
-				} ).join( '\n' ) );
+			this.$hiddenInput.prop( 'defaultValue', this.getItems().map( ( item ) => item.getData() ).join( '\n' ) );
+			this.on( 'change', ( items ) => {
+				this.$hiddenInput.val( items.map( ( item ) => item.getData() ).join( '\n' ) );
 				// Trigger a 'change' event as if a user edited the text
 				// (it is not triggered when changing the value from JS code).
 				this.$hiddenInput.trigger( 'change' );
-			}.bind( this ) );
+			} );
 		}
 
 	};
@@ -99,11 +95,11 @@
 		const widget = this;
 
 		this.getRequestData()
-			.then( function ( data ) {
+			.then( ( data ) => {
 				// Reset
 				widget.menu.clearItems();
 				widget.menu.addItems( widget.getOptionsFromData( data ) );
-			} ).always( function () {
+			} ).always( () => {
 				// Parent method
 				mw.widgets.TitlesMultiselectWidget.super.prototype.onInputChange.call( widget );
 			} );
diff --git a/resources/src/mediawiki.widgets/mw.widgets.UsersMultiselectWidget.js b/resources/src/mediawiki.widgets/mw.widgets.UsersMultiselectWidget.js
index bd41636eca96..5c0a56d04823 100644
--- a/resources/src/mediawiki.widgets/mw.widgets.UsersMultiselectWidget.js
+++ b/resources/src/mediawiki.widgets/mw.widgets.UsersMultiselectWidget.js
@@ -139,13 +139,13 @@
 					list: 'allusers',
 					auprefix: inputValue,
 					aulimit: this.limit
-				} ).done( function ( response ) {
+				} ).done( ( response ) => {
 					let suggestions = response.query.allusers;
 
 					const selected = this.getSelectedUsernames();
 
 					// Remove usernames, which are already selected from suggestions
-					suggestions = suggestions.map( function ( user ) {
+					suggestions = suggestions.map( ( user ) => {
 						if ( selected.indexOf( user.name ) === -1 ) {
 							return new OO.ui.MenuOptionWidget( {
 								data: user.name,
@@ -154,9 +154,7 @@
 							} );
 						}
 						return undefined;
-					} ).filter( function ( item ) {
-						return item !== undefined;
-					} );
+					} ).filter( ( item ) => item !== undefined );
 
 					// Remove all items from menu add fill it with new
 					this.menu.clearItems();
@@ -171,7 +169,7 @@
 					this.menu.toggle( true );
 
 					this.popPending();
-				}.bind( this ) ).fail( this.popPending.bind( this ) );
+				} ).fail( this.popPending.bind( this ) );
 			}
 
 		} else {