title: Date.getDay() javascript returns wrong day
body: <p>Hi I'm new in javascript
  I have such javascript code</p>
  
  <pre><code>alert(DATE.value);
  var d = new Date(DATE.value);
  var year = d.getFullYear();
  var month = d.getMonth();
  var day = d.getDay();
  alert(month);
  alert(day);
  if(2012 &lt; year &lt; 1971 | 1 &gt; month+1 &gt; 12 | 0 &gt;day &gt; 31){
      alert(errorDate);
      DATE.focus();
      return false;
  }
  </code></pre>
  
  <p>take for instance: <code>DATE.value = "11/11/1991"</code></p>
  
  <p>when I call <code>alert(day);</code> it shows me <code>3</code>;<br>
  when I call <code>alert(d);</code> it is returns me correct info.</p>