Arrays in JS

Array

finger A collection of data , Each data is called Elements , Array can Store elements of any type , An array is a A set of data is stored in a single variable name Under the elegant way

How to create an array

• utilize new Create array
• Create an array using array literals

var  Array name  = new Array()

A Use capital letters

Create an array using array literals

• The literal value of the array is 【】
• Declaring an array and assigning values is the initialization of the array

Get array elements

Index of array ：

The ordinal number used to access an array element （ from 0 Start ）

Array name [ Reference no. ]

Traversal array

Because the array index number is from 0 Start , therefore i Must be from 0 Start

Write when outputting arr[i]     i The counter is used as an index number

The length of the array

arr.length

New elements in the array

It can be modified by length Increase the length and index number of array elements

• By modifying the length Length to achieve the purpose of array expansion
• length Properties are readable and writable

Add new array elements by modifying the array index

• You can append array elements by modifying the array index
• You cannot assign values to array names directly , Otherwise, the previous data will be overwritten