Validate Email Address in Javascript

Need a quick client-side email validation? Below is a simple JavaScript regular expression to validate email addresses.

/^\w.+@[a-zA-Z_.]+?\.[a-zA-Z.]{2,3}$/

..and to use it:

if (/^\w.+@[a-zA-Z_.]+?\.[a-zA-Z.]{2,3}$/.test(email)) alert("Success");
else alert("Fail");

This covers the basics — checking for an @ symbol, a domain, and a valid TLD. Keep in mind that email validation via regex is notoriously tricky. The full RFC 5322 spec allows for some wild edge cases that no simple regex can cover.

For most forms, a basic check like this is fine for catching typos. The only way to truly validate an email address is to send a confirmation email to it. If you want something more robust on the client side, consider using the built-in HTML5 type="email" attribute on your input field, which handles validation natively in modern browsers.