Regex

pendemv · November 28th, 2008, 11:15 AM

Hello All,

I want to validate a text box for email validation using regex. The issue i am facing is:
1) i have 2 textboxes where 1st will carry firstname_lastname
and the 2nd textbox will carry @domain name.

2) I want to validate the first box for firstname_lastname where it should check for the '_' character.

Please help.

Old Pedant · November 28th, 2008, 06:09 PM

So do you want to do this client-side in JavaScript or server side in JSP code??? Or, to be safe, do you want to do it both places?

pendemv · December 1st, 2008, 03:22 AM

I want to do this in JavaScript. Thank you

Old Pedant · December 1st, 2008, 04:17 PM

Code:

<script>
function checkForValidName( fld )
{
    var re = /^[a-z]+\_[a-z]+$/i
    // optional:  Trim spaces from ends first:
    var txt = fld.value.replace( /(^\s+|\s+$)/g, "" );
    // optional:  Put the trimmed value back in place
    fld.value = txt;
    if ( ! re.test( txt ) )
    {
        alert("Must be in form firstname_lastname");
        fld.focus();
        fld.select();
        return false;
    }
    return true;
}
</script>

Then invoke that function via something like
     <form onsubmit="return checkForValidName( this.SomeFieldName );">

Note that this RE will allow names as simple as
    a_b
If you want to insist on (say) a minimum of 3 letters in first name and 2 in second, you could do
    var re = /^[a-z]{3,99}\_[a-z]{2,99}$/i

Or use whatever numbers you feel comfortable with.

pendemv · December 8th, 2008, 08:29 AM

Thank you!