I think you are trying to merge the jQuery array of items found by ".stuff" and ".morestuff"
var $obj1 = $(".stuff"); var $obj2 = $(".morestuff"); $obj1.add($obj2); alert($obj1.length); the problem is the line $obj1.add($obj2); doesn't assign the value back to variable "$obj1", so the next line had no idea that $obj1 was changed this would var $obj1 = $(".stuff"); var $obj2 = $(".morestuff"); $obj1 = $obj1.add($obj2); alert($obj1.length); as shown here: http://jsbin.com/akuto/edit