​x
 
<html>
<head>
<script type="text/javascript">
function isKeyPressed(event)
{
  if (event.ctrlKey==1)
    {
    alert("The CTRL key was pressed!")
    }
  else
    {
    alert("The CTRL key was NOT pressed!")
    }
  }
​
</script>
</head>
<body onmousedown="isKeyPressed(event)">
​
<p>Click somewhere in the document. An alert box will tell you if you pressed the CTRL key or not.</p>
​
</body>
</html>
​