How to add an element to an array in es6

3 methods: 1. Use unshift() to insert an element at the beginning, the syntax is "array object.unshift(element)"; 2. Use push() to insert an element at the end, the syntax "Array object.push(element)"; 3. Use concat(), the syntax is ""array.concat(element)".

The operating environment of this tutorial ：windows7 system, ECMAScript version 6, Dell G3 computer.

es6 Three ways to add an element to an array

1 , Use the unshift() function

The unshift() function can insert elements at the beginning of the array. This function can append one or more parameter values ​​to the head of the array:

array.unshift(元素1, 元素2, ..., 元素X)

The first parameter Element1 is the new element 0 of the array, the second parameter Element2 is the new element 1, and so on, and finally returns the length of the array after adding the element.

Let’s take a closer look at the following example:

var a = [0];  //定义数组
console.log(a);  //返回[0]

a.unshift(1);  //增加1个元素
console.log(a);  //返回[1,0]

2. Use the push() function

array.push(元素1, 元素2, ..., 元素X)

var a = [0];  //定义数组
console.log(a);  //返回[0]

a.push(2);  //增加1个元素
console.log(a);  //返回[0,2]

3. Use the concat() function

var a = [1,2,3,4,5];  //定义数组
console.log(a);  
var b = a.concat(6);  //为数组a连接1个元素
console.log(b);

##Explanation: The concat() method will create and return a new array instead of adding new elements to the original one; but unshift The () method will add elements based on the original array.

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