"JS Notes" array of those things [0]

The array in JS is a special object, the index is its property, and the integer index is internally converted to a string type.

1 Creation of arrays

New keyword method:var arr=new Array ()

var arr=New Array (Ten//var arr=New Array  //3

Literal method: var arr=[]

var arr=//0var arr=[1,2,3];

It is recommended to create an array using the literal method.

2 Properties

Length Property Long

3 methods

3.1 Adding a Delete to an element

Push (): Adds an element at the end of the array. The return value is the new array length.

var arr=[1,2,3];arr.push (4//  [1,2,3,4]

Pop (): deletes the element at the end of the array and returns it.

var arr=[1,2,3//[+]

unshift (): adds an element at the beginning of the array. The return value is the new array length.

var arr=[1,2,3];arr.unshift (0//  [0,1,2,3]

Shift (): Deletes the first element of the array and returns it.

var arr=[0,1,2,3//[[+]

Splice ():

Splice (Start,len,i1,i2 ...): Will i1,12 ... insert the position of the Len element from start.

var arr=[0,1,2,3];arr.splice (1,2,0,0); Console.log (arr); //   [0, 0, 0, 3]

var arr=[0,1,2,3];arr.splice (1,2,0//  [0, 0, 3]

Splice (Start,len): Removes Len elements from start.

var arr=[0,1,2,3];arr.splice; Console.log (arr); // [0, 3]

Concat (): Inserts a new element after the array to form a new array.

var arr=[0,1,2,3]; var newarr= Arr.concat,console.log (newarr); // [0, 1, 2, 3, 1, 2]

3.2 Find

IndexOf ():

Finds the parameter element starting at the beginning of the array, returns the index of the parameter element, and returns 1 if the element does not exist.

LastIndexOf ():

Finds from the last element of the array.

3.3 Converting to a string

ToString ()

Join ()

3.4 Sort

Reverse (): reverse order

Sort (): Sorts the strings in alphabetical order.

var arr=[' A ', ten, ' C ', 3];console.log (Arr.sort ()); // [3, "A", "C"]

Sort () can receive a function as the ordering method in the function of the parameter execution.

The function receives two parameters, and if the return value is positive, the order of the two numbers is exchanged in the array, otherwise it is not exchanged. Here are two ways to sort from small to large with sort:

function Compare (A, a    ) {return A-b;} var arr=[1,20,3,10//  [1, 3, ten,]

function Compare (b) {    if (a>b)          return 1;     if (a<b)                   return -1;} var arr=[1,20,3,10//[1, 3, ten,]

"JS Notes" array of those things [0]