Attributes: fix setting selected on an option in IE<=11

Fixes jquerygh-2732
Close jquerygh-2840

Author: timmywil

src/attributes/prop.js

@@ -79,6 +79,12 @@ jQuery.extend( {
 	}
 } );
 
+// Support: IE <=11 only
+// Accessing the selectedIndex property
+// forces the browser to respect setting selected
+// on the option
+// The getter ensures a default option is selected
+// when in an optgroup
 if ( !support.optSelected ) {
 	jQuery.propHooks.selected = {
 		get: function( elem ) {
@@ -87,6 +93,16 @@ if ( !support.optSelected ) {
 				parent.parentNode.selectedIndex;
 			}
 			return null;
+		},
+		set: function( elem ) {
+			var parent = elem.parentNode;
+			if ( parent ) {
+				parent.selectedIndex;
+
+				if ( parent && parent.parentNode ) {
+					parent.parentNode.selectedIndex;
+				}
+			}
 		}
 	};
 }

test/unit/attributes.js

@@ -796,6 +796,37 @@ QUnit.test( "prop('tabindex', value)", function( assert ) {
 	assert.equal( clone[ 0 ].getAttribute( "tabindex" ), "1", "set tabindex on cloned element" );
 } );
 
+QUnit.test( "option.prop('selected', true) affects select.selectedIndex (gh-2732)", function( assert ) {
+	assert.expect( 2 );
+
+	function addOptions( $elem ) {
+		return $elem.append(
+			jQuery( "<option/>" ).val( "a" ).text( "One" ),
+			jQuery( "<option/>" ).val( "b" ).text( "Two" ),
+			jQuery( "<option/>" ).val( "c" ).text( "Three" )
+		)
+		.find( "[value=a]" ).prop( "selected", true ).end()
+		.find( "[value=c]" ).prop( "selected", true ).end();
+	}
+
+	var $optgroup,
+		$select = jQuery( "<select/>" );
+
+	// Check select with options
+	addOptions( $select ).appendTo( "#qunit-fixture" );
+	$select.find( "[value=b]" ).prop( "selected", true );
+	assert.equal( $select[ 0 ].selectedIndex, 1, "Setting option selected affects selectedIndex" );
+
+	$select.empty();
+
+	// Check select with optgroup
+	$optgroup = jQuery( "<optgroup/>" );
+	addOptions( $optgroup ).appendTo( $select );
+	$select.find( "[value=b]" ).prop( "selected", true );
+
+	assert.equal( $select[ 0 ].selectedIndex, 1, "Setting option in optgroup selected affects selectedIndex" );
+} );
+
 QUnit.test( "removeProp(String)", function( assert ) {
 	assert.expect( 6 );
 	var attributeNode = document.createAttribute( "irrelevant" ),