Make removeClass smart enough to remove duplicates. Fixes #11923

src/attributes.js

@@ -71,31 +71,30 @@ jQuery.fn.extend({
 	},
 
 	removeClass: function( value ) {
-		var classNames, i, l, elem, className, c, cl;
+		var removes, className, elem, c, cl, i, l;
 
 		if ( jQuery.isFunction( value ) ) {
 			return this.each(function( j ) {
 				jQuery( this ).removeClass( value.call(this, j, this.className) );
 			});
 		}
-
 		if ( (value && typeof value === "string") || value === undefined ) {
-			classNames = ( value || "" ).split( core_rspace );
+			removes = ( value || "" ).split( core_rspace );
 
 			for ( i = 0, l = this.length; i < l; i++ ) {
 				elem = this[ i ];
-
 				if ( elem.nodeType === 1 && elem.className ) {
-					if ( value ) {
-						className = (" " + elem.className + " ").replace( rclass, " " );
-						for ( c = 0, cl = classNames.length; c < cl; c++ ) {
-							className = className.replace(" " + classNames[ c ] + " ", " ");
-						}
-						elem.className = jQuery.trim( className );
 
-					} else {
-						elem.className = "";
+					className = (" " + elem.className + " ").replace( rclass, " " );
+
+					// loop over each item in the removal list
+					for ( c = 0, cl = removes.length; c < cl; c++ ) {
+						// Remove until there is nothing to remove,
+						while ( className.indexOf(" " + removes[ c ] + " ") > -1 ) {
+							className = className.replace( " " + removes[ c ] + " " , " " );
+						}
 					}
+					elem.className = value ? jQuery.trim( className ) : "";
 				}
 			}
 		}

test/unit/attributes.js

@@ -1055,6 +1055,16 @@ test("removeClass(Function) with incoming value", function() {
 	QUnit.reset();
 });
 
+test("removeClass() removes duplicates", function() {
+	expect(1);
+
+	var $div = jQuery( jQuery.parseHTML("<div class='x x x'></div>") );
+
+	$div.removeClass("x");
+
+	ok( !$div.hasClass("x"), "Element with multiple same classes does not escape the wrath of removeClass()" );
+});
+
 var testToggleClass = function(valueObj) {
 	expect(17);