Detect Alt Gr (Alt Graph) modifier on key press

Question

In the javascript Event object, there are some boolean values to check if modifier keys are pressed:

• ctrlKey: CTRL key.

Answer 1

The altGraphKey in webkit browsers no longer appears to exist (as at September 2013) and the behaviour of Firefox has changed. Browser behaviours for the AltGr key currently appear to be:

• Webkit (Chrome) - ctrlKey: true, altKey: true
• IE 8 - ctrlKey: false, altKey: true
• IE 10 - ctrlKey: true, altKey: true
• Mozilla (Firefox) - ctrlKey: true, altKey: true

Which is to say, they are all currently consistent (apart from IE8, which remains consistently inconsistent).

The following snippet should catch Alt Gr - but not Alt or Ctrl - in modern browsers. You will need a special case for IE8 however:

if (event.ctrlKey && event.altKey) {
    // Appears to be Alt Gr
}