Performance comparison of three array copy methods in javascript_javascript skills

1. Three array copy methods
1. by slice
var arr = [1, 2, 3], copyArr;
copyArr = arr.slice();

2. by concat
var arr = [1, 2, 3], copyArr;
copyArr = arr.concat();
3 . by loop
var arr = [1, 2, 3], copyArr = [];
for (var i=0, j=arr.length; i
2. Test environment
Browsers: IE6, FF 3.5.5, Opera 10, Chrome 4.0.249, Safari 4.0.3

3. Test case
Use the above 3 methods to test an array with 500,000 items Carry out the copy operation, and then compare the time spent by the three methods.

<meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>Performance comparison of three array copy methods</title> <meta name="description" content="鏁扮粍澶嶅埗, slice, concat"> <meta name="keywords" content="鏁扮粍澶嶅埗, slice, concat"> <div class="section"> <p>We use an array with 500,000 sub-items as the test object (IE will not crash!).</p> <button id="J_CopyBySlice">copyBySlice</button> <button id="J_CopyByConcat">copyByConcat</button> <button id="J_CopyByLoop">copyByLoop</button> </div>
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4. Test Results (click the image to see a larger image)

5. Conclusion For IE, use slice; for non-IE, use concat.
For webkit, use concat ; For other browsers, use slice.