Summary of js array clearing (deletion) Method

There are many methods for clearing data in js. Below I will introduce several methods for clearing data, which can be used to compare with the performance of various array clearing methods. For more information, see.

Clearing the array is a common JavaScript job, but I often see it in an incorrect way. In many cases, developers will create a new array, such as the following:

Assign a value to []

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MyArray = []; // bad Method Var ary = [1, 2, 4]; Ary = []; // assign a value to an empty array to clear the original array.

Creating an empty array to clear it is obviously not the best method. You should set the length attribute of the array to 0:

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MyArray. length = 0; // good!

Set length to zero to clear the current array, instead of creating another empty array! This helps you avoid array pointers. If you use the preceding method:

 

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A = [1, 2, 3, 4, 5] B = A = [] Console. log (B) // [1, 2, 3, 4, 5]. The original array is still not cleared. A just points to the new empty array.

Set the length to 0 to clear both A and B.

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Var a = []; For (var I = 0; I <1000000; I ++ ){ A. push (I ); } Var start = new Date (); // A = []; A. length = 0; Var end = new Date (); Alert (end-start );

The other attributes of the array are retained, and the method 3 is not retained. Many people think that method 2 is more efficient, because it only assigns a value to length, and method 3 creates an object again. It is tested that method 3 is highly efficient.