prevent login Form from submission (AJAX) when credentials dont match (return false not working)

Question

This is my form:

 <form name="loginform" method="POST" action="login" onsubmit="return validateLogin()">            
<div>  User Name  :<input class="input" name="username" type="text" /> </div> 
<div> Password  :<input class="input" name="password" type="password" /> </div>        
<div> id="yaha" style="color:red;font:bold 16px garamond"</div>                         
<input style="font-weight:bold;" type="submit" value="Login" />

javascript code is as shown:

function validateLogin()
{
var x1=document.forms["loginform"];
if(//validations)
      {
       return false;
      }
 else
{    goajax(x1.username.value,x1.password.value);}        
 }//validate login ends...

var requ = null;

function goajax( u,  p)
{
requ=new XMLHttpRequest();
//code for posting ajax data
requ.onreadystatechange=display;

} 
function display()
{
if(requ.readyState == 4)
{
    if(requ.status == 200)
    {
    var message = requ.responseText;
    alert("message==="+message);
    var x;
    if(message.trim() == "ok")
        {
        var x1=document.forms["loginform"];
        return true;
        }
        else if(message.trim() == "no")
        {
        document.getElementById('yaha').innerHTML="Invalid Username or Password!!!";
        x1.password.value="";
        return false;
        }
        else if(message.trim() == "nv")
        {
        document.getElementById('yaha').innerHTML="Account not Activated";
        return false;
        }
    }     
}

}

My question is : I am getting the responses from the server as desired but in case of undesired responses, the form is getting submitted even after "return false;" (see function display())

Please scroll down to function display() i don't want the form to be submitted when message is "no" or "nv". basically "return false" is not working

Answer 1

Another way is to cancel the default event (in this case the submit)

Like this:

function validateLogin(e)
{
var x1=document.forms["loginform"];
if(//validations)
      {
       e.preventDefault();
       return false;
      }

Answer 2

See: jQuery preventDefault();

Try posting with jQuery (If you are using it in the website)

Answer 3

I've been doing a lot of this in my current project using jQuery this way:

$('#form').submit(function () {

call_function_to_validate_and_submit(); return false;

});

Whenever I have a javascript error (syntax or other) the form gets submitted (like in a normal html form with no ajax) even if validation fails. My point is that you might have a syntax error somewhere in there.