JavaScript timing

So you quickly want to know how long a piece JavaScript takes to execute? And you want to know it now? Here's a simple way to do it. You will get a popup with the amount of milliseconds your piece of code took.

var start = new Date().getTime();
// Your blazingly fast JaveScript code goes here
alert(new Date().getTime() - start);

Remember that everything else your computer is doing (in and outside of the browser) will influence this. Keep that in mind and don't focus on every millisecond change between runs.