Autocomplete: Rewrite with a delay instead of appending the live region

This fixes the issue caused by https://bugs.jqueryui.com/ticket/9357.
We now empty the live region instead of appending to it, and we do so
after a brief timeout so the live region isn't updated on every mousemove
event or when quickly traversing through options.

Fixes gh-2002
Closes gh-2031

tests/unit/autocomplete/core.js

@@ -293,6 +293,7 @@ QUnit.test( "simultaneous searches (#9334)", function( assert ) {
 } );
 
 QUnit.test( "ARIA", function( assert ) {
+	var ready = assert.async();
 	assert.expect( 13 );
 	var element = $( "#autocomplete" ).autocomplete( {
 			source: [ "java", "javascript" ]
@@ -308,11 +309,13 @@ QUnit.test( "ARIA", function( assert ) {
 		"Live region's role attribute must be status" );
 
 	element.autocomplete( "search", "j" );
+	setTimeout( function() {
 		assert.equal( liveRegion.children().first().text(),
 			"2 results are available, use up and down arrow keys to navigate.",
 			"Live region for multiple values" );
 
 		element.simulate( "keydown", { keyCode: $.ui.keyCode.DOWN } );
+		setTimeout( function() {
 			assert.equal( liveRegion.children().filter( ":visible" ).text(), "java",
 				"Live region changed on keydown to announce the highlighted value" );
 
@@ -320,31 +323,37 @@ QUnit.test( "ARIA", function( assert ) {
 				event.preventDefault();
 			} );
 			element.simulate( "keydown", { keyCode: $.ui.keyCode.DOWN } );
+			setTimeout( function() {
 				assert.equal( liveRegion.children().filter( ":visible" ).text(), "javascript",
 					"Live region updated when default focus is prevented" );
-
 				element.autocomplete( "search", "javas" );
+				setTimeout( function() {
 					assert.equal( liveRegion.children().filter( ":visible" ).text(),
 						"1 result is available, use up and down arrow keys to navigate.",
 						"Live region for one value" );
-
 					element.autocomplete( "search", "z" );
+					setTimeout( function() {
 						assert.equal( liveRegion.children().filter( ":visible" ).text(), "No search results.",
 							"Live region for no values" );
-
+						assert.equal( liveRegion.children().length, 1,
-	assert.equal( liveRegion.children().length, 5,
+							"Should be one child in the live region after the above" );
-		"Should be five children in the live region after the above" );
 						assert.equal( liveRegion.children().filter( ":visible" ).length, 1,
 							"Only one should be still visible" );
 						assert.ok( liveRegion.children().filter( ":visible" )[ 0 ] === liveRegion.children().last()[ 0 ],
 							"The last one should be the visible one" );
-
 						element.autocomplete( "destroy" );
 						assert.equal( liveRegion.parent().length, 0,
 							"The liveRegion should be detached after destroy" );
+						ready();
+					}, 110 );
+				}, 110 );
+			}, 110 );
+		}, 110 );
+	}, 110 );
 } );
 
 QUnit.test( "ARIA, aria-label announcement", function( assert ) {
+	var ready = assert.async();
 	assert.expect( 1 );
 	$.widget( "custom.catcomplete", $.ui.autocomplete, {
 		_renderMenu: function( ul, items ) {
@@ -361,8 +370,11 @@ QUnit.test( "ARIA, aria-label announcement", function( assert ) {
 		liveRegion = element.catcomplete( "instance" ).liveRegion;
 	element.catcomplete( "search", "a" );
 	element.simulate( "keydown", { keyCode: $.ui.keyCode.DOWN } );
+	setTimeout( function() {
 		assert.equal( liveRegion.children().filter( ":visible" ).text(), "People : anders andersson",
 			"Live region changed on keydown to announce the highlighted value's aria-label attribute" );
+		ready();
+	}, 110 );
 } );
 
 QUnit.test( "ARIA, init on detached input", function( assert ) {

ui/widgets/autocomplete.js

@@ -66,6 +66,7 @@ $.widget( "ui.autocomplete", {
 
 	requestIndex: 0,
 	pending: 0,
+	liveRegionTimer: null,
 
 	_create: function() {
 
@@ -267,8 +268,10 @@ $.widget( "ui.autocomplete", {
 				// Announce the value in the liveRegion
 				label = ui.item.attr( "aria-label" ) || item.value;
 				if ( label && String.prototype.trim.call( label ).length ) {
-					this.liveRegion.children().hide();
+					clearTimeout( this.liveRegionTimer );
-					$( "<div>" ).text( label ).appendTo( this.liveRegion );
+					this.liveRegionTimer = this._delay( function() {
+						this.liveRegion.html( $( "<div>" ).text( label ) );
+					}, 100 );
 				}
 			},
 			menuselect: function( event, ui ) {
@@ -663,8 +666,10 @@ $.widget( "ui.autocomplete", $.ui.autocomplete, {
 		} else {
 			message = this.options.messages.noResults;
 		}
-		this.liveRegion.children().hide();
+		clearTimeout( this.liveRegionTimer );
-		$( "<div>" ).text( message ).appendTo( this.liveRegion );
+		this.liveRegionTimer = this._delay( function() {
+			this.liveRegion.html( $( "<div>" ).text( message ) );
+		}, 100 );
 	}
 } );