jQuery#addBack supports an optional selector that can be used to filt…

…er the prior set before adding it back. Fixes #9800

src/traversing.js

@@ -143,8 +143,9 @@ jQuery.fn.extend({
 			jQuery.unique( all ) );
 	},
 
-	addBack: function() {
-		return this.add( this.prevObject );
+	addBack: function( selector ) {
+		var prior = this.prevObject;
+		return this.add( selector == null ? prior : prior.filter(selector) );
 	}
 });
 

test/unit/traversing.js

@@ -403,11 +403,12 @@ test("has(Arrayish)", function() {
 });
 
 test("addBack()", function() {
-	expect(4);
+	expect(5);
 	deepEqual( jQuery("#en").siblings().addBack().get(), q("sndp", "en", "sap"), "Check for siblings and self" );
 	deepEqual( jQuery("#foo").children().addBack().get(), q("foo", "sndp", "en", "sap"), "Check for children and self" );
 	deepEqual( jQuery("#sndp, #en").parent().addBack().get(), q("foo","sndp","en"), "Check for parent and self" );
 	deepEqual( jQuery("#groups").parents("p, div").addBack().get(), q("qunit-fixture", "ap", "groups"), "Check for parents and self" );
+	deepEqual( jQuery("#select1 > option").filter(":first-child").addBack(":last-child").get(), q("option1a", "option1d"), "Should contain the last elems plus the *filtered* prior set elements" );
 });
 
 test("siblings([String])", function() {