Basic knowledge of JS arrays (summary)

This article summarizes some basic knowledge of JS arrays for everyone. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Array: Store a set of ordered data

The role of array: Store multiple items at once Data

How to define an array:

1. Constructor defines array: var array name=new Array();

2. Literal Define an array in a quantitative way: var array name=[];

[Related course recommendations: JavaScript video tutorial]

The meaning of the following arrays:

var 数组名=new Array(); //  空数组
var 数组名=new Array(值); //  数组定义了,有长度
var 数组名=new Array(值1,值2,值3....); //  定义数组并且有多个数据
var 数组名=[]; //  空数组
var 数组名=[值1,值2,值3]; //  有三个数据

Array elements: is the data stored in the array

Array length: is the number of elements in the array

Array index (subscript): Start from 0 and end with the length of the array minus 1

Set the element value of the array through the subscript: Array name [index] =value

Access the element value of the array through subscript:Array name[index]

The meaning of the following array:

var arr1=new Array();//空数组
var arr2=new Array(5);//长度为5的数组,每个数据的值是undefined
var arr3=new Array(1,2,3,4,5);//长度为5分数组,
var arr4=[];//空数组
var arr5=[1,2,3];//长度为3的数组
var arr6=["red","blue","green",1,true];//数组中元素的值的类型可以不一样

var arr7=[];
//设置数组的元素的值
arr7[0]=10;
arr7[1]=20;

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