How can I tell if an event comes from right Ctrl key?

Question

I have an event listener in Javascript, I can tell whether a key event is Ctrl (e.keyCode == 17), but how can I know this Ctrl comes from the right one or left one?

You can't. I'm sorry. I feel your pain. – zzzzBov Jan 04 '11 at 05:41 — zzzzBov, Jan 04 '11 at 05:41

score 6 · Answer 1 · answered Jan 04 '11 at 05:33

6

Just a quick note: I wouldn't base an architecture / design on the availability of the right control key - many laptop keyboards may not have two control keys.

answered Jan 04 '11 at 05:33

JustinByrne

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1

alex · Accepted Answer · 2013-02-07T23:50:30.377

3

I don't think the keyCode is different.

You can use e.ctrlKey for a better way to determine if the control key was pressed.

It seems Flash can not tell which one is pressed either (either that or coded incorrectly).

edited Feb 07 '13 at 23:50

answered Jan 04 '11 at 05:26

alex

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They are abstracted. E.g. I can choose a ton of different options for each of them in my Ubuntu Keyboard settings. – Ivo Wetzel Jan 04 '11 at 05:34
You can definitely write software that differentiates between the two on a low level, so no, it can't be abstracted on the hardware level. It's probably abstracted on the OS level, though. – Sasha Chedygov Jan 04 '11 at 08:26
MSIE can differentiate the left and right Ctrl key, see my answer on that point. – Julien Kronegg Feb 07 '13 at 15:41

score 1 · Answer 3 · answered Feb 07 '13 at 15:39

MSIE provides a ctrlLeftproperty on most events. The property values are:

true if the left key was pressed during the event
false if the left key was not pressed.

You can combine event.ctrlKey and event.ctrlLeft to determine if the right Ctrl key was pressed:

if (event.ctrlKey) {
    if (event.ctrlLeft) {
        // left Ctrl key pressed
    } else {
        // right Ctrl key pressed
    }
} else {
    // no Ctrl key pressed
}

Note that the ctrlLeftproperty in a keyup is undefined because the Ctrl key is not pressed anymore.

Tested under MSIE7 and MSIE9. Does not work under Firefox.

See http://help.dottoro.com/ljqlvhuf.php for details.

Not very useful unfortunately if it's IE only. – alex Feb 07 '13 at 23:52 — alex, Feb 07 '13 at 23:52

score 1 · Answer 4 · answered Nov 17 '14 at 21:02

1

If you traced it you will find the same key is used for both (17) .. I think it is not possible to differentiate

answered Nov 17 '14 at 21:02

Muhammad Soliman

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score 1 · Answer 5 · edited May 23 '17 at 12:24

I don't know if it was available when this was asked, but you can distinguish left- from right-ctrl, as well as alt and shift. You can now use the KeyboardEvent.DOM_KEY_LOCATION_* properties to make this distinction.

See Can javascript tell the difference between left and right shift key?

Be aware though, I discovered that Chrome appears to have a defect in its implementation. See How can I distinguish left- and right- shift, ctrl, and alt keys onkeyup in Chrome with Javascript

score 1 · Answer 6 · answered Jan 16 '17 at 14:22

There is event.location property for left ctrl key it will be 1 for right one 2, you can check browser support on canIuse

if (e.which == 17) {
   if (event.location == 1) {
      // left ctrl key
   } else if (event.location == 2) {
      // right ctrl key
   }
}

How can I tell if an event comes from right Ctrl key?

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