Array Method in JavaScript

Source: Internet
Author: User

Shift: Delete the first entry of the original array and return the value of the deleted element. If the array is empty, undefined is returned.
Var a = [1, 2, 3, 4, 5];
Var B = a. shift (); // a: [2, 3, 4, 5] B: 1

Unshift: add the parameter to the beginning of the original array and return the length of the array.
Var a = [1, 2, 3, 4, 5];
Var B = a. unshift (-2,-1); // a: [-2,-,] B: 7
Note: In IE6.0, the test return value is always undefined, and in FF2.0, the test return value is 7. Therefore, the return value of this method is unreliable. You need to use splice instead of this method when returning the value.

Pop: Delete the last entry of the original array and return the value of the deleted element. If the array is empty, undefined is returned.
Var a = [1, 2, 3, 4, 5];
Var B = a. pop (); // a: [1, 2, 3, 4] B: 5

Push: add the parameter to the end of the original array and return the length of the array.
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 consisting of adding parameters to the original array.
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, 7]

Splice (start, deleteCount, val1, val2,...): Delete the deleteCount item from the start position, and insert val1, val2 ,...
Var a = [1, 2, 3, 4, 5];
Var B = a. splice (, 9); // a: [,] B: []
Var B = a. splice (0, 1); // same as shift
A. splice (0, 0,-2,-1); var B = a. length; // same as unshift
Var B = a. splice (a. length-1, 1); // same as pop
A. splice (a. length, 7); var B = a. length; // same as push

Reverse: returns the reverse order of the array.
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): sorts arrays by specified parameters.
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 consisting of items from the original array that specify the start subscript to the end subscript
Var a = [1, 2, 3, 4, 5];
Var B = a. slice (); // a: [, 5] B: [, 5]

Join (separator): A string is set up for the elements of the array. The separator is separator. If it is omitted, a comma is used as the separator by default.
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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