Archive for the ‘JavaScript’ Category

Speeding up jQuery’s each function

Saturday, January 23rd, 2010

In my previous post, “Investigating JavaScript Array Iteration Performance“, I found that among a selection of different array iteration methods, jQuery’s each function was the slowest. It’s worth mentioning again that these investigations are pretty academic – array iteration and looping speed is unlikely to be the source of performance problems compared to actual program logic, DOM manipulation, string manipulation, etc. I just found it interesting to poke into how things work in different browsers. That said, with the recent release of jQuery 1.4 emphasizing performance so much, I wanted to see what if anything could be done to speed up each (which is used inside jQuery all over the place), and whether it would made much of a difference.

Again, the details are after the jump.
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Investigating JavaScript Array Iteration Performance

Sunday, December 13th, 2009

The other day I was working on some JavaScript code that needed to iterate over huge arrays. I was using jQuery’s $.each function just because it was simple, but I had heard from a bunch of articles on the web that $.each was much slower than a normal for loop. That certainly made sense, and switching to a normal for loop sped up my code quite a bit in the sections that dealt with large arrays.

I’d also recently seen an article on Ajaxian about a new library, Underscore.js that claimed to include, among other nice Ruby-style functional building blocks, an each function that was powered by the JavaScript 1.5 Array.forEach when it was available (and degrading for IE). I wondered how much faster that was than jQuery’s $.each, and that got me to thinking about all the different ways to iterate over an array in JavaScript, so I decided to test them out and compare them in different browsers.

This gets pretty long so the rest is after the jump.
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