Javascript Performance Optimisation?

Question

Just wondering what the best tool is to really check JS scripts and look at ways of improving overall performance to the "utmost maximum" in terms of size and speed?

Answer 1

I usually follow the following steps.

1. Using JSLint - http://www.jslint.com/ optimize the script.
   • Use YUI Compressor.
   • Profile the script. See Firebug & YSlow.

Answer 2

I like using Firebug's profiler for improving overall speed. It'll show you how many times each function is called, how long it took to execute (average and overall), and the percentage of the total JS execution time the function took. I'm not a big fan of micro-optimization, so I don't use any tools to get the "utmost maximum" out of my code, but the profiler helps weed out the bigger issues.

As for size, I use the YUI compressor to minimize the size of my JavaScript files. (There are other JavaScript minification tools out there, I am just most used to YUI's.)

Answer 3

And if you've got Safari 4, you can use the JavaScript Profiler in its Web Inspector.

For compressing your code, I like the JavaScript Packer by Dean Edwards.

Steve