isValidEmail.js

1-isValidEmail.js

function isValidEmail(string){
    string = string||'';
    var lastseg = (string.split('@')[1]||'').split('.')[1]||'',
        input = document.createElement('input');
        input.type = "email";
        input.required = true;
        input.value = string;
    return !!(string && (input.validity && input.validity.valid) && lastseg.length);
}

isValidEmail("");// -> false
isValidEmail("asda");// -> false
isValidEmail("asda@gmail");// -> false
isValidEmail("asda@gmail.com");// -> true

2-Description.md

Similar to getAbsoluteUrl, you can use a modern browser’s native ability to validate emails from a string by creating an temporary element and testing its validity.

If you wanted to support older browsers you could fall back to trying a regex instead, but with this method you can be ensured that whatever the user’s browser considers to be a valid email, you’re using the exact same logic (however strict or lenient that might be).

http://davidwalsh.name/essential-javascript-functions#comment-502973