js中replace匹配变量的几种方法

//第一种
let variable = "var";
let exp = new RegExp(variable, "g");
let str = "varvar";
// 相当于 str.replace(/var/g,"i")
console.log(str.replace(exp, "i")); //ii

//第二种
let variable = "var";
let pattern = eval（"/" + variable + "/g");
let str = "varvar";
// 相当于 str.replace(/var/g,"i")
console.log(str.replace(pattern, "i")); //ii