JSFiddle - React, Tailwind, and code Playground

JavaScript

var isEmail_re       = /^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$/;

function isEmail (s) {
   return String(s).search (isEmail_re) != -1;
}

alert(isEmail ('"xyz"<[email protected]>'));