I need a way to submit a form only if email is valid. If email is NOT valid then show ONLY an alert ( below you can see my code ).

JAVASCRIPT:

 function validateEmail(email) { 

    var re = /^(([^<>()[]\.,;: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,}))$/;

    return re.test(email);

 } 





 function continueornot() {

    if(validateEmail(document.getElementById('emailfield').value)){

    // ok

    }else{ alert(email not valid); return false;}

 }

HTML:

<form method=post action=register.php enctype=multipart/form-data>

<table>

<tr><td>Email:</td></tr>

<tr><td><input type=text size=30 name=email id=emailfield> </td></tr>

<tr><td>Password:</td></tr>

<tr><td><input type=password size=30 name=password> </td></tr>

</table>

<input name=steptwo value=Create Account type=submit onclick=continueornot();/>

</form>

The problem is that the form is submitted even if the email is NOT valid.

How can I resolve this problem ?