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)

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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