The method of array in JS

(Refer to the user example)

One JS does not change the original array method:

• concat: Concatenate multiple arrays, returning a new array
• Join: Place all elements in an array with a parameter as a delimiter into one character
• Slice: Slice (start,end), returns the selected element Array.slice (start, end)

var ary = [1,2,3,4,5];

        var res = Ary.slice (1,3);

        console.log (ary); //[1,2,3,4,5]    console.log (res); //[2,3]

• map, does not change the original array ary.map (function(item,index,ary){}) item: Each item index: Index ary: Current array
• filter, does not change the original array ary.filter (function(item,index,ary){}) item: Index of each index : ARY: Current array
• ForEach Traversal, does not change the original array ary.foreach (function(item,index,ary){}) item: index per item index ARY: Current array

The method of changing the original array in the second JS:

• Shift: Delete the first element and return the deleted element, empty is undefined

var ary = [' A ',' B ',' C '];

var res = Ary.shift ();

Console.log (ary); //[' B ', ' C '] Console.log (res); //a

• Pop: Delete the last one and return the deleted element

var ary = [' A ',' B ',' C '];

var res = Ary.pop ();

Console.log (ary); //[' A ', ' B '] Console.log (res); //C

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

var ary = [' A ',' B ',' C '];

var res = ary. unshift (' d ',' e ');

Console. log (ary); //["D", "E", "a", "B", "C"] console. Log (res); // 5

• Push: Adds an element to the end of the array and returns the new length

var ary = [' A ',' B ',' C '];

var res = ary. push (' d ',' e ', ' f ');

Console.   log (ary); //["a", "B", "C", "D", "E", "F"] console. Log (res); //6

• Reverse: Reverse Array order
• Sort: Sorting an array
• Splice:Splice (start,length,item) Delete, increment, replace array element, return the deleted array, no delete does not return

Added features

Ary.splice (N,0,x,......,y);

Starting with the index n of the array, deleting 0 items, adding a new item to the front of index N, and the third parameter starting to fill the deleted item location.

var ary = [1,2,3,4,5];var res = ary.splice(1,0,6,7);//从索引值1开始，删除0项console.log(ary); // [1, 6, 7, 2, 3, 4, 5]console.log(res); // [] 删除0项，返回一个空数组

Modified Features
Ary.splice (N,M,X);
Start with the index n of the array, delete the M entry, and add the X to the front of index n

 var ary = [1,2,3,4,5];var res = ary.splice (1,2, 6,7); console.log (ary); //[1, 6, 7, 4, 5]console.log (res); //[2,3]             

The method of array in JS