Question

Just tested this function to validate an email..However,it does not validate the presence or absence of the dot in the email..Why this is happening and how can I fix this?

<script type="text/javascript">
  function isEmail(textbox){

    var reg4 =/^(\w+)@(\w+).(\w+)$/;
    if(reg4.test(textbox.value)){

            return true;
        }

    return false;
}
</script>

Answer 1

No, it’s insufficient.

In particular, it doesn’t handle all these (legal) variants:

1. quoted user parts, e.g. "my name"@example.com

2. Internationalised domain names (IDNs)

3. Domains with more than two labels

4. Domains with only one label (yes, those are legal)

5. Hyphens in domain names

6. user@[1.2.3.4]

Validating an e-mail address via a regexp is very hard. See section 3.4.1 of RFC 5322 for the formal syntax definition.