I was reading this article from SitePoint earlier about how inefficient the JavaScript is behind Google’s new Closure library, and saw some interesting discussion about caching an array’s length property before entering a ‘for’ loop. This is what I’m talking about:

// uncached length property
for(var x=0; x < myArray.length; x++){}
 
// cached length property
for(var x=0, len=myArray.length; x < len; x++){}

I saw this tip and didn’t think twice about it; I’ve always been told that caching the length property is indeed faster. I then saw a couple comments saying otherwise:

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