title: JQuery mobile - return false not preventing form submit
body: <p>The <code>alert()</code> works fine, but <code>return false</code> does not stop the form being posted - any ideas?</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
  function form_val() {
      //Check date
      var email=document.getElementById('email').value;
      var passw=document.getElementById('password').value;
      if(email==''||email==null||passw==''||passw==null) {
          alert('Please fill in both fields.');
          return false;
      }  
  
  }
  &lt;/script&gt;
  
  &lt;form action="userlogin.html" method="post" name="log_form" onsubmit="return form_val();"&gt;
      &lt;div data-role="fieldcontain"&gt;
          &lt;input type="email" name="email" id="email" value="" placeholder="Email Address" /&gt;
          &lt;input type="password" name="password" id="password" value="" placeholder="Password" /&gt;
          &lt;div class="ui-grid-a"&gt;
          &lt;div class="ui-block-a"&gt;
              &lt;button type="submit" name="login" value="" data-theme="c"&gt;Sign In&lt;/button&gt;
          &lt;/div&gt;
          &lt;div class="ui-block-b"&gt;
              &lt;br /&gt;
              &lt;a href="http://mobile.*****.com/lostpswd.html" rel="external" style="font-size:10px; padding-left:10px;"&gt;Forgotten Password?&lt;/a&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>