event Properties   DHTML Events

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DOM Level 2 Specification.

Retrieves the current state of the ALT key.

HTML	N/A
Script	[ bAltKeyDown= ] event.altKey

false	Indicates that the ALT key is up.
true	Indicates that the ALT key is down.

The property is read-only with no default value.

This property is used to indicate whether the ALT 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

ctrlKey, shiftKey, Key Capture Routines