JavaScript has instanceof operator, which is way faster for determining the type of a variable than converting the variable to string and comparing strings. And unfortunately the latter is what jquery is using. In my benchmarks it is more than 30x faster to use instanceof rather than toString. It is true that this 30x in this case can not make a difference for a script that is executed several (thousand) times, but there are two reasons to fix this. 1) jquery is widely used worldwide, which means this is wasting millions of millions of CPU cycles worldwide as we speak and degrading the web perfomance worldwide. 2) as jquery is reputable library and many people are using it as an example and learning from it, it is setting very bad example and driving developers' skills down worldwide. I've wrote an article with benchmarks for the benefits of using instanceof http://bobef.net/articles/proper-type-determination-in-javascript . Regards.