JavaScript libraries are good, but be aware...

So, I've been using jQuery for a while now, and I have absolutely no complaints. Looking back at when I first began using it, my code started to get more efficient, but then I realized that, in using jQuery, I was able to do things in less typed code, but was actually adding MORE things for the browser to do. If you're going to use a jQuery wrapped object more than once, and you're not chaining jQuery commands, save it to a variable.



is super inefficient. Everytime you go $("#tbody"), you're initializing a new jQuery object..

This could be chained by going:


You do add an additional .end() call, which isn't as bad as the first example.

If you didn't want to do this, you could save the initialized object to a variable:




In this example, jQuery is only initialized around the tbody once. This is a very simple example, but I think you get the point. In a large application, CPU cycles matter! Efficiency is key. Building good coding habits is never a bad thing.