Question

Hi This is a simple question i guess:
My requirement is in the Text box whenever user enters mail, the domain name should be appended automatically.Also the name entered should not allow special characters except ‘.’ ‘_’ in reality. Also the user should not be allowed to add any other domain except which is specified in the property file.This is in JAVASCRIPT

Answer 1

Why not simply show

|_____________| @yourdomain.com

and do the appending either when submitting (onsubmit event) or on the server side?

e.g.

function email_form_submit(event)
{
    event = event || window.event;

    if (event.preventDefault)
        event.preventDefault();

    if (event.stopPropagation)
        event.stopPropagation();
    else
        event.cancelBubble = true;

    var form = document.getElementByID('your form id');
    var element = document.getElementByID('your email form element id');
    element.value = element.value + "yourdomain.com";

    form.submit();

    return false;
}

See http://msdn.microsoft.com/en-us/library/ms536972%28VS.85%29.aspx

EDIT
quick validation regex. Note: not tested

function validate_email_address(event)
{
    event = event || window.event;

    var regex = /^[a-zA-Z0-9._]+@yourdomain\.com$/;

    var element = document.getElementByID('your email form element id');
    element.value = element.value + "yourdomain.com";

    if (!regex.test(element.value))
    {
        alert("Invalid Email");
        if (event.preventDefault)
            event.preventDefault();
        return false;
    }

}

Edit: fixed syntax error