title: Cannot read property 'value' of undefined
body: <p>I have a simple form like this:</p>
  
  <pre><code>&lt;form method="post" id="login"&gt;
  
  Username: &lt;input type="text" value="" name="usr" /&gt;
  Password: &lt;input type="password" value="" name="pw"/&gt;
  &lt;input type="submit" id="log" name="log" value="Login" style="width:250px;"/&gt;&lt;br/&gt;
  
  &lt;/form&gt;
  </code></pre>
  
  <p>But i keep getting cannot read property for my javascript with this line:</p>
  
  <pre><code>var usr = login.usr.value;
  var pw = login.pw.value;
  </code></pre>
  
  <p>What is the reason i get this error ?</p>