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    <p>There is not a big difference between these definitions, except that the first way uses the array/object literal and the second the array/object constructor.</p> <p>The array constructor may return different results, depending on the number of arguments passed in. If you pass in one argument, a new empty array is created of the length of that argument. For example:</p> <pre><code>// arr1 is the same as arr2 var arr1 = new Array(1, 2, 3, 4); var arr2 = [1, 2, 3, 4]; alert(arr1.length == arr2.length); // true alert(arr1[0]); // 1 alert(arr2[0]); // 1 </code></pre> <p>But, passing in one argument results differently:</p> <pre><code>// arr3 has length 200 and is empty, while arr4 has length 1 and contains a number var arr3 = new Array(200); var arr4 = [200]; alert(arr3.length == arr4.length); // false alert(arr3[0]); // 'undefined' alert(arr4[0]); // 200 </code></pre> <hr> <p>The speediest way to define an array or object is of course the literal way, because you don't need to call the constructor first. Anyway, the actual speed difference is negligible, really.</p> <p>I did a <a href="http://jsfiddle.net/pLyH5/" rel="nofollow noreferrer"><strong>speed test</strong></a> in Chrome 6, in which I defined 20 times 10000000 the same array <code>1, 2, 3</code>, which gave these results:</p> <pre><code>Average speed per 10000000 calls Array Constructor : 226.55 ms Array Literal : 159.1 ms </code></pre> <p>As you can see, the array literal is 67,45ms faster per 10000000 array definitions.</p>
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    1. POIs it better to write: var arr=[]; than var arr=new Array();?
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    1. POIs it better to write: var arr=[]; than var arr=new Array();?
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    1. COthe question also here what more fast for computer to run
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      1. USYosef
    2. COwhile it is an interesting point that the `Array` constructor treats the arguments differently based on how many there are, i think it is completely misleading to list that as a difference in a comparison between the two ways of creating an array. `[]` is not a method that you invoke with arguments, any more than `var a = "test"` is four arguments passed to a `""`-function. it is nothing more than a syntax for creating arrays, that only implicitly deals with assigning dimensions.
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    3. COhttp://jsperf.com/literal-vs-constructor-array
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