JavaScript array operation function Summary _javascript tips

In fact, usually use more of the push and pop, but still write down to use later.

shift : Deletes the first item of the original array and returns the value of the deleted element, or returns undefined if the array is empty

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.shift (); a:[2,3,4,5] B:1

unshift : Adds a parameter to the beginning of the original array and returns the length of the array

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.unshift ( -2,-1); a:[-2,-1,1,2,3,4,5] B:7

Note: The test return value under IE6.0 is always undefined,ff2.0 the test return value is 7, so the return value of this method is unreliable, and it is necessary to use splice instead of this method with the return value. This article is from www.45it.com

pop : Deletes the last item of the original array and returns the value of the deleted element, or returns undefined if the array is empty

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.pop (); a:[1,2,3,4] B:5

Push : Adds a parameter to the end of the original array and returns the length of the array

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.push (6,7); a:[1,2,3,4,5,6,7] B:7

concat : Returns a new array that adds a parameter to the original array.

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.concat (6,7); a:[1,2,3,4,5] b:[1,2,3,4,5,6,7]

Splice (Start,deletecount,val1,val2,...) : Deletes the DeleteCount entry from the start position and inserts the Val1,val2 from that location,...

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.splice (2,2,7,8,9); a:[1,2,7,8,9,5] b:[3,4]
var B = a.splice (0,1); With shift
A.splice (0,0,-2,-1); var B = a.length; With Unshift
var B = A.splice (a.length-1,1); Same pop
A.splice (a.length,0,6,7); var B = a.length; Same push

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Splice Detailed :

The Splice function method removes one or more elements from an array and, if necessary, inserts a new element at the position of the removed element, returning the removed element.

Arrayobj.splice (Start, DeleteCount, [item1[, item2[, ...) [, Itemn]]]

Where Arrayobj must be selected. An Array object.

Start is a required option. Specifies that the starting position of the element is removed from the array, which is calculated starting at 0.

DeleteCount is a required option. The number of elements to remove.

Item1, item2,.. ., Itemn is a must option. The new element to insert at the location of the removed element.

The splice function method in JavaScript can modify arrayobj by removing the specified number of elements from the start position and inserting new elements. The return value is a new Array object that consists of the removed element.

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Reverse : reverse-order the array

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.reverse (); a:[5,4,3,2,1] b:[5,4,3,2,1]

Sort (orderfunction): sorting by specified array of parameters

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.sort (); a:[1,2,3,4,5] b:[1,2,3,4,5]

Slice (start,end): Returns a new array of items from the original array specifying the start subscript to the end subscript

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = a.slice (2,5); a:[1,2,3,4,5] b:[3,4,5]

Join (separator): Sets the element of an array to a string, separator as a delimiter, and omitted by default with a comma as the delimiter

Copy Code code as follows:

var a = [1,2,3,4,5];
var B = A.join ("|"); a:[1,2,3,4,5] B: "1|2|3|4|5"

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