JS实现将手机号中间的几位数字变成****功能

const str = “hello”
let arr = str.split("");
console.log(arr); // h,e,l,l,o

const arr = ["a","b","c","d"];
arr.splice(1,2,"e","gg","d"); //从数字索引的第一位开始，删除两个内容，向数组添加”e“和”gg“两项。
console.log(arr); // ["a","e","gg"，"d"];

const arr = ['a','b','c','d'];
let result = arr.join();
console.log(result); // a,b,c,d

const telphone = '13300009999';
let telArr = telphone.split();
telArr.splice(3,4,'****');
let result = telArr.join(); //因为不会改变原数组，需要用一个新的变量去接收
console.log(result); // 1330****999

const str = 'Hello World';
let result = str.substr(1,4);
console.log(result); //ello

const telphone = '13300009999';
let result = telphone.substr(0,4) + '****' + telphone.substr(8);
console.log(result);// 1330****999
//第二句代码解释：
//使用 `substr` 方法截取电话号码的前四位，然后拼接上'****'，
//再拼接上电话号码从索引为8开始的剩余部分，将结果赋值给变量result。

const str = 'Hello World';
let result = str.substring(1,4);
console.log(result); //ell

const str = 'Hello World';
let result = str.replace("Hello","Hi");
console.log(result); //Hi World

const telphone = '13300009999';
let result = telphone.replace(telphone.substring(3,8),'****');
console.log(result);// 1330****999

const telphone = '13300009999';
const reg = /(\d{4})\d{4}(\d{3})/;
let result = telphone.replace(reg,"$1****$2");
console.log(result);// 1330****999