A simple JS function for checking if an Email is valid.

email.coffee

# Credit: https://stackoverflow.com/a/46181/1544937

validEmail = (email = "@") ->

    return /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test String(email).toLowerCase()

email.js

// Generated by CoffeeScript 2.7.0
// Credit: https://stackoverflow.com/a/46181/1544937

var validEmail;

validEmail = function(email = "@") {
  return /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(String(email).toLowerCase());
};