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    <p>It is considered by most a bad practice to extend native objects like <code>Array</code>. That is what the post you mentioned was getting at. The concern is you do not know how this will effect the behavior of other scripts.</p> <p>Here is an example of a scenario where poorly written caused issues once the array prototype was manipulated. This is a scenario I ran into once on a large code based which was really hard to track down:</p> <pre><code>function BadUseOfForLoop(){ //You should NEVER use a for in loop to iterate over an array //although some people do this and it works until you extend Array var arr = [1,2,3,4]; for (key in arr){ console.log(arr[key]); } } BadUseOfForLoop(); console.log("Extend Array..."); Array.prototype.sortBy = function(){ return "Doesnt matter..."; }; BadUseOfForLoop(); </code></pre> <p>Output:</p> <pre><code>1 2 3 4 Extend Array... 1 2 3 4 function (){ return "Doesnt matter..."; } </code></pre> <p><a href="http://jsfiddle.net/vTwRY/" rel="nofollow">http://jsfiddle.net/vTwRY/</a></p> <p>One thing you could do to avoid the caveat is simply not extend the Array object and create a helper to do this for you.</p> <pre><code>var ArrayHelper = { sortBy : function(arr, prop){ return function(){ var so = srt.sortOrder == 'asc' ? 1 : -1; var key = srt.sortKey; var result = 0; console.log(srt.sortKey + ' ' + srt.sortOrder + ':'); return function (a, b) { if (srt.isComputed) { result = (a[key]() &lt; b[key]()) ? -1 : (a[key]() &gt; b[key]()) ? 1 : 0; } else { result = (a[key] &lt; b[key]) ? -1 : (a[key] &gt; b[key]) ? 1 : 0; } return result * so; }; } } }; </code></pre> <p>And then in your code...</p> <pre><code>ArrayHelper.sortBy(myItems,sortList[k]); </code></pre> <p>instead of</p> <pre><code>myItems.sortBy(sortList[k]); </code></pre> <p><a href="http://jsfiddle.net/DcN7y/1/" rel="nofollow">Working demo</a></p> <p>For further reading on the subject this <a href="http://perfectionkills.com/extending-built-in-native-objects-evil-or-not/" rel="nofollow">Perfection Kills</a> post discusses whether or not extending native objects is a good idea and you will see it is not a cut and dry issue. Above, I layed out an issue that is not discussed in this blog post but really can cause conflicts with other code.</p>
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    1. POSort javascript array by property or function value
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    1. COmarteljn - at the risk of sounding like an idiot, I don't know how to do this. I like the way you're going... can you show me how to implement your proposal?
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    2. COYes, I will elaborate in the answer after I eat lunch:)
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    3. CO@Kevin - I implemented your sort in the way I suggested. Functionally, it is doing the same thing you did but in way which avoids the possible issues of extending native objects.
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