ES6 正则表达式的扩展

let regex=/xyz/i
console.log(regex.exec("XYZabc"))

let regex=new RegExp("xyz","i")
console.log(regex.exec("XYZabc"))


let regex=new RegExp(/xyz/i)
console.log(regex.exec("XYZabc"))

let regex=new RegExp(/xyz/,"i")
console.log(regex.exec("XYZabc"))