How to modify the value of an array in es6

Method: 1. Use splice() to delete, add or replace elements, the syntax is "array.splice(subscript, number of elements, new value 1,..., new value X)"; 2. Re-copy the specified subscript element with the syntax "array name [subscript value] = new value;"; 3. Use replaceAll() to replace all specific elements with the syntax "str=arr.toString().replaceAll(" Search value","new value");newArr=str.split(",");".

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

es6 Several ways to modify array values

Method 1: Use the splice() method

Use the splice() method to delete elements, add elements or replace elements

array.splice(index,howmany,item1,.....,itemX)

Parameters	Description
index	Required. Specifies where to add/remove elements. This parameter is the subscript of the array element to start inserting and/or deleting, and must be a number.
howmany	Optional. Specifies how many elements should be removed. Must be a number, but can be "0". If this parameter is not specified, all elements starting from index to the end of the original array will be deleted.
item1, ..., itemX	Optional. New elements to be added to the array

Return value: an array composed of all deleted elements. If no elements are deleted, an empty array will be obtained

Example 1:

var arr = [1,2,3,4,5,6,7,8,9,10];
console.log(arr);
//删除
arr.splice(1,2);
console.log(arr);    //打印：[1,4,5,6,7,8,9,10]

Example 2:

var arr = [1,2,3,4,5,6,7,8,9,10];
console.log(arr);
//替换
arr.splice(1,2,'b','c');
console.log(arr);    //打印：[1, "b", "c", 6, 7, 8, 9, 10]

Example 3:

var arr = [1,2,3,4,5,6,7,8,9,10];
console.log(arr);
//添加，如果不删除元素，但是又存在第三个或者3+的参数，就会有添加的功能
arr.splice(1,0,'a','b','c');
console.log(arr);    //打印：[1, "a", "b", "c", "b", "c", 6, 7, 8]

Method 2: Access the specified element through the subscript and re-copy it

Syntax for accessing the array element and re-assigning the value:

数组名[指定下标值]=新值;

The example is as follows:

var arr = [1,2,3,4,5];  //声明一个数组
console.log(arr);
arr[0] = 0;  //修改第一个元素，重新赋值为0
arr[2] = "A";  //修改第三个元素，重新赋值为2
console.log(arr);

Method 3: Use replaceAll() to replace all specific elements

replaceAll is Used to replace characters in a string. Of course, when we convert "array" and "string", it can also be applied to arrays. Generally used with regular expressions.

const newStr = str.replaceAll(regexp|substr, newSubstr|function)

Example:

var arr = [3, 5, "-", "9", "-"];
var newArr = [];

var str = arr.toString().replaceAll("-","新");	//数组转字符串并替换所有特定元素

console.log(str);				//3,5,新,9,新
newArr = str.split(",");		//字符串转数组
console.log("newArr",newArr);	
//newArr (5) ["3", "5", "新", "9", "新"]

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