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In the JavaScript array, the concat method can be used to join multiple arrays to form a new array, and we do not want to change the original array when joining, so will the concat method change the original array? The answer is no change. When you use the concat method, the members of the new array are added to the end of the original array, and then a new array is returned. The original array is not changed, even if other types of values are passed in, they are added to the end of the array as new elements, and the original array is also not changed.

1. Concat method

You can add array elements or merge two arrays

Only one copy of the joined array will be returned, but the original array will not be changed

Second, parameters

Parameter can be array,string,number,object

The order of each parameter is the element of the parameter (if the parameter is an array) or the parameter itself (if the parameter is not an array).

It is not recursive into nested array parameters.

III. Remarks on concat ()

1. If the parameter is an array type (Array), all the elements in the parameter array are concatenated to the end of the current array in turn; if it is of another type, add itself as an element to the end of the current array.

2. This method does not change the existing array, but only returns a copy of the joined array.

4. Return value

Returns a new array, and if an array is passed as an argument to the concat () method, the elements in the array are added instead of the array itself.

V. examples

Var a = [1Jing 2jue 3]; [xss_clean] (a.concat (4Jing 5))

Output

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