how to validate email

Question

I need to add to add the following characteristics to this form but I'm stuck. any help would b greatly appreciated. Thanks

One or more word characters
Exactly one at-sign
One or more word characters

Exactly one period Two or more characters that are a-z, A-Z, 0-9, period, or hyphen

<!DOCTYPE html>
  <html>
  <head>
  <script>
    function validateForm()
    {
      var x=document.forms["myForm"]["email"].value;
      var atpos=x.indexOf("@");
      var dotpos=x.lastIndexOf(".");
      if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
      {
         alert("Not a valid e-mail address");
         return false;
      }
    }
  </script>
</head>

<body>
  <form name="myForm" action="demo_form.asp" onsubmit="return validateForm();" method="post">
    Email: <input type="text" name="email">
    <input type="submit" value="Submit">
  </form>
</body>

Requiring "exactly one period" in an email address will reject a significant number of perfectly valid addresses (e.g, `user@example.co.uk`, `user@sub.example.com`, `user.name@example.com`). — , Mar 10 '14 at 03:57
What you have there seems fine to me; no need to make up more rules than necessary. — Ja͢ck, Mar 10 '14 at 03:58
you can use the code given on @xdazz comment and improve it with some more checks to the postfix. — majidarif, Mar 10 '14 at 03:58

score 1 · Answer 1 · edited May 23 '17 at 12:21

function isValidEmailAddress(emailAddress) {
    var pattern = new RegExp(/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i);
    return pattern.test(emailAddress);
};

This function will work in your case

To call it like this

if( !isValidEmailAddress( emailaddress ) ) { /* do stuff here */ }

keep in mind that no 100% regex email check exists!

Checkout this link

https://stackoverflow.com/a/2855946/2630817

If you're going to snatch [someone else's answer](http://stackoverflow.com/a/2855946/1338292), you may as well flag this question as a duplicate of the corresponding question. — Ja͢ck, Mar 10 '14 at 04:00
Hey @jack i have just included link there if user find difficulty to search — Just code, Mar 10 '14 at 04:02

score 0 · Answer 2 · answered Mar 10 '14 at 04:00

0

Try this:

<script>        
   function validateForm(){

       var email=document.forms["myForm"]["email"].value;

       var filter = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

       if (!filter.test(email)) {
           alert("Not a valid e-mail address");
           return false;
       }
       return true;
   }
</script>

answered Mar 10 '14 at 04:00

suresh gopal

3,138
6
27
58

Some explanation would be useful along with the code, especially given that this does not implement the rules that the OP asked for. – nnnnnn Mar 10 '14 at 04:06
So this is basically ripped from [this answer](http://stackoverflow.com/a/46181/1338292) and the expression eliminates valid email addresses and should therefore not be used. – Ja͢ck Mar 10 '14 at 04:09

score 0 · Answer 3 · answered Mar 10 '14 at 04:47

Try this pure javascript:

function checkEmail() {

    var email = document.getElementById('txtEmail');
    var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;

    if (!filter.test(email.value)) {
    alert('Please provide a valid email address');
    email.focus;
    return false;
 }

how to validate email

3 Answers3