Array Method Summary

Slice: Slice --Returns a new array--copy array: Arr.slice (0)
Arrayobject.slice (start,end): slices   

var arr= [1,2,3,4]arr.slice (1,3); // [2, 3]arr.slice (0); // [1, 2, 3, 4] copies an array, or the loop element is copied. The copy array is a copy and B===a is false. B=a is a pointer, B===a is true

Concat: Concatenate two or more arrays, return a new array, copy array: Arr.concat ()

Concat () joins two or more arrays and returns the result.

Arrayobject.concat (Arrayx,arrayx,......, Arrayx)

var arr=[1,2];arr.concat (3);//[1, 2, 3]arr.concat ([3,4]),//[1, 2, 3, 4], take out the elements of the array arr.concat ([[[6,7],[8,9]]);//[1, 2, array[2]0:61:7length:2__proto__: array[0], array[2]0:81:9length:2__proto__: array[0]]//out is just the elements in the first layer of the array OH

Change the original array (add return length, delete deleted elements):

　　Reverse: Reverses the order of elements in the original array (implemented by sort), returns the original array after the change

　　Sort: Sorts the elements of the original array, and returns the original array after the change

var arr=[1,3,2];//undefinedarr//[1, 3, 2]arr.sort (function (A, b) {return b-a})//[3, 2, 1]arr.sort (function (A, b) {return A-B})//[1, 2, 3]

　　Push: Returns the array length by adding an element to the end of the array　　　

Arr.push ([])//5arr//[1, 2, 3, "a", array[0]]

　　Pop: Delete end element and return end element

Arr.pop ()//[]arr//[1, 2, 3, "a"]

　Shift: Delete an element and returns the value of the first element

Arr.shift ()//1arr//[2, 3, "a"]

　Unshift: Adds an element to the beginning of the array and returns the new length

Arr.unshift ("B")//4arr//["B", 2, 3, "a"]

　Splice to/from an array, and returns the deleted item

Arrayobject.splice (index,howmany,item1,....., ItemX)

Parameters	Description
Index	Necessary. An integer that specifies the location of the Add/remove item, using a negative number to specify the position from the end of the array.
Howmany	Necessary. The number of items to delete. If set to 0, the item is not deleted.
Item1, ..., ItemX	Optional. Adds a new item to the array.

arr//["B", 2, 3, "a"]arr.splice (2,0, "William")//[]arr//["B", 2, "William", 3, "a"]

　　

Array Method Summary