How to create an array in JavaScript?

I believe everyone is familiar with arrays. Whether in php or in JavaScript, arrays are an indispensable part, and they are also the ones we deal with the most when learning programming One of the data types, so today we will introduce to you how to create an array in JavaScript?

Method to create an array in JavaScript:

1. Use the constructor of the array object Array(), like creating an object (actually an object), use the newoperator to instantiate an array object.

What is created in this way is an array without elements, and the number of elements is empty

[cc]
//创建一个空数组
var arr = new Array();
//其长度为——0
alert(arr.length);
[/cc]

2. Use the constructor Array() to directly and explicitly specify the array The first n elements.

The length of the array created in this way is n, and the subscripts of the array are from 0 to n-1

[cc]
//创建一个数组，前七位分别为’a',’b',’c',’d',1,2,3
var arr = new Array(‘a’,'b’,'c’,'d’,1,2,3);
//数组的长度为7
alert(arr.length);
[/cc]

3. Use the constructor new Array() , directly add an integer as a parameter to directly specify the length of the array. The value of each element of the created array is undefined

[cc]
//指定数组长度为10
var arr = new Array(10);
alert(arr.length);
//数组元素为undefined
alert(arr[0]);
[/cc]

4. Create using direct quantities

var arr = [];//创建一个空数组
var arr2 = [1,2,3];//创建一个有三个元素的数组

5. Use the constructor to create

a、var arr1 = new Array();//创建空数组
b、var arr2 = new Array(10)；//创建一个长度为10的数组
c、var arr3 =  new Array(5,4,3,2,1)；//创建数组并初始化

The simplest way to create an array in JavaScript:

1. Array declaration method

（1）： arrayObj = new Array(); //创建一个数组。

The code is as follows:

var arr1 = new Array();

（2）：arrayObj = new Array([size])　
创建一个数组并指定长度，注意不是上限，是长度。

The code is as follows:

var a = new Array(5);

（3）：arrayObj = new Array([element0[, element1[, ...[, elementN]]]])　
创建一个数组并赋值。

The code is as follows:

var a = new Array(["b", 2, "a", 4,]);

（4）：arrayObj = [element0, element1, ..., elementN]　
创建一个数组并赋值的简写，注意这里中括号不表示可省略。

The code is as follows:

var a = ["b", 2, "a", 4,];

(Note): Pay attention to the difference between "[]" and without "[]"

The code is as follows:

var a = new Array(5); //指创建长度为5的数组
var a = new Array([5]); //指创建一个数组，长度为1，并且第一位是5

2. Common methods of arrays

3. Array operations (passing address)

var t2=new Array();
t2[0]=1;
t2[1]=2;
test2(t2); //传地址（数组）
 
function test2(var2) {
for(var i=0;i
var2[i]=var2[i]+1;
}
}
for(var i=0;i
alert(t2[i]);
}

Summary:

There are many ways to create arrays in JavaScript, each method has its own benefits, depending on your own needs Choose the most appropriate creation method, I hope it will help you!

Related recommendations:

1.The simplest code for javascript to create an array

2.Example of using javascript to create an associative array of arrays

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