js：使用正则RegExp实现字符串全部替换replaceAll

var re = /pattern/flags;

var re = new RegExp("pattern", "flags");

let re = /name/igm
let text = "What is your name? My name is Tom"
let ret = text.replace(re, "age")
console.log(ret);
// What is your age? My age is Tom

let keyword = "name"
let text = "What is your name? My name is Tom"
let reg = new RegExp(keyword, 'igm')
let ret = text.replace(reg, "age")
console.log(ret);
// What is your age? My age is Tom