function validate(form_id,email) { var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/; var address = document.forms[form_id].elements[email].value; if(reg.test(address) == false) { alert('Invalid Email Address'); return false; } }