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PO$.each() vs for() loop - and performance
 

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    <p>These are mainly just some things I've been wondering, maybe someone can give me a little more insight on them, i'll share what i've noticed so far as well!</p> <p>First thing i've been wondering... is there any difference good or reason to use:</p> <p><code>$('element').each(function (i, el) { });</code> </p> <p>-- versus -- </p> <p><code>$.each($('element'), function (i, el) { });</code> </p> <p>Looking at the jQuery docs I can't see any rhyme or reason for one or the other (maybe you know an instance or additional things one can do over the other.</p> <p><strong>But more importantly I'm concerned with <em>speed</em> here</strong></p> <pre><code>// As opposed to $.each() looping through a jQuery object // -- 8x faster for (var i = 0, $('.whatever').length; i &lt; len; i++) { $('.whatever')[i] // do stuff } </code></pre> <p>If you check out this <strong><a href="http://jsfiddle.net/3ySng/1/" rel="noreferrer">jsFiddle DEMO here</a></strong>, you'll see the difference in speed is basically equivalent with either of them, but more importantly I feel like I should <em>always</em> be using <code>for()</code> loops...</p> <p>I was just unit testing (looping through each of 5 different scenario functions, 50,000 times), simply looping through a bunch of list items, and setting a <code>data-newAttr</code>, nothing special.</p> <hr> <p><strong>QUESTION :: I guess my biggest question is, why not <em>always</em> use for loops while iterating through an object?? Is there even a point to using $.each()? Do you always use for() loops even when going through jQuery objects?</strong></p> <p><strong><a href="http://jsfiddle.net/3ySng/1/" rel="noreferrer">jsFiddle DEMO here</a></strong></p> <pre><code>Function type: Execution Time: _testArea.each() + $(this) 1947 &lt;-- using $(this) slows it down tremendously $.each() + $(this) 1940 _testArea.each() + el(plain JS) 458 &lt;-- using the Element speeds things up $.each() + el(plain JS) 452 for() loop + plainJS[0] iteration 236 &lt;-- over 8x faster </code></pre> <p>Just my 2cents. :)</p>
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    1. USMark Pieszak - DevHelp.Online
    1. USMark Pieszak - DevHelp.Online
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    1. COAs Joe Armstrong once wrote in response to a similar question on the Erlang mailing list, "Just write the most beautiful program you can." Let performance problems come to you. Will you really be working on pages that iterate 50,000 times? If yes, then by all means optimize.
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    2. COWhat would a `for` loop iterating over jQuery DOM elements look like?
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    3. CO@Jordan I would guess about 1730ms .. give or take a hundred :) [As Jordan points out, these micros are *not* correctly testing the "8x" stated; they only show it is "2x" faster in that case.]
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