event Properties   DHTML Events

DOM Level 2 Specification.

Retrieves the state of the CTRL key.

The property is read-only with no default value.

This property is used to indicate whether the CTRL key was depressed during the firing of the event. On some platforms this key may map to a different key name.

This example tracks whether the Alt, Ctrl, or Shift key returns true ( was pressed ) when an onclick event fires. Click the button with or without any of the keys mentioned and see.

Here's the code for that exercise:

<script language="JavaScript">
<!--
function chkKey ( ) {
   var ctrlKey = document.layers ? event.modifiers &
     Event.CONTROL_MASK : event.ctrlKey;
   var altKey = document.layers ? event.modifiers &
     Event.ALT_MASK : event.altKey;
   var shiftKey = document.layers ? event.modifiers &
     Event.SHIFT_MASK : event.shiftKey;
   alert ( 'Ctrl ' + ctrlKey + ' \nAlt ' + 
     altKey + ' \nShift " + shiftKey )
}
//-->
</script>

event

altKey, shiftKey, Key Capture Routines