Added support for the new .closest() method (very useful for event delegation).

src/core.js

@@ -338,6 +338,17 @@ jQuery.fn = jQuery.prototype = {
 			}) ), "filter", selector );
 	},
 
+	closest: function( selector ) {
+		return this.map(function(){
+			var cur = this;
+			while ( cur && cur.ownerDocument ) {
+				if ( jQuery(cur).is(selector) )
+					return cur;
+				cur = cur.parentNode;
+			}
+		});
+	},
+
 	not: function( selector ) {
 		if ( typeof selector === "string" )
 			// test special case where just one selector is passed in

test/unit/core.js

@@ -1309,6 +1309,14 @@ test("filter()", function() {
 	equals( j.filter("[name]").length, 0, "Check node,textnode,comment to filter the one span" );
 });
 
+test("closest()", function() {
+	expect(4);
+	isSet( jQuery("body").closest("body").get(), q("body"), "closest(body)" );
+	isSet( jQuery("body").closest("html").get(), q("html"), "closest(html)" );
+	isSet( jQuery("body").closest("div").get(), [], "closest(div)" );
+	isSet( jQuery("#main").closest("span,#html").get(), q("html"), "closest(span,#html)" );
+});
+
 test("not()", function() {
 	expect(8);
 	equals( jQuery("#main > p#ap > a").not("#google").length, 2, "not('selector')" );