How does one capture a Mac's command key via JavaScript?

Question

EDIT: As of 2019, e.metaKey is supported on all major browsers as per the MDN.

Note that on Windows, although the ⊞ Windows key is considered to be the "meta" key, it is not going to be captured by browsers as such.

This is only for the command key on MacOS/keyboards.

---

Unlike Shift/Alt/Ctrl, the Cmd (“Apple”) key is not considered a modifier key—instead, you should listen on keydown/keyup and record when a key is pressed and then depressed based on event.keyCode.

Unfortunately, these key codes are browser-dependent:

• Firefox: 224
• Opera: 17
• WebKit browsers (Safari/Chrome): 91 (Left Command) or 93 (Right Command)

You might be interested in reading the article JavaScript Madness: Keyboard Events, from which I learned that knowledge.

You can also look at the event.metaKey attribute on the event if you are working with keydown events. Worked wonderfully for me! You can try it here.

I found that you can detect the command key in the latest version of Safari (7.0: 9537.71) if it is pressed in conjunction with another key. For example, if you want to detect ⌘+x:, you can detect the x key AND check if event.metaKey is set to true. For example:

var key = event.keyCode || event.charCode || 0;
console.log(key, event.metaKey);

When pressing x on it's own, this will output 120, false. When pressing ⌘+x, it will output 120, true

This only seems to work in Safari - not Chrome

Basing on Ilya's data, I wrote a Vanilla JS library for supporting modifier keys on Mac: https://github.com/MichaelZelensky/jsLibraries/blob/master/macKeys.js

Just use it like this, e.g.:

document.onclick = function (event) {
  if (event.shiftKey || macKeys.shiftKey) {
    //do something interesting
  }
}

Tested on Chrome, Safari, Firefox, Opera on Mac. Please check if it works for you.

For people using jQuery, there is an excellent plugin for handling key events:

jQuery hotkeys on GitHub

For capturing ⌘+S and Ctrl+S I'm using this:

$(window).bind('keydown.ctrl_s keydown.meta_s', function(event) {
    event.preventDefault();
    // Do something here
});

Here is how I did it in AngularJS

app = angular.module('MM_Graph')

class Keyboard
  constructor: ($injector)->
    @.$injector  = $injector
    @.$window    = @.$injector.get('$window')                             # get reference to $window and $rootScope objects
    @.$rootScope = @.$injector.get('$rootScope')

  on_Key_Down:($event)=>
    @.$rootScope.$broadcast 'keydown', $event                             # broadcast a global keydown event

    if $event.code is 'KeyS' and ($event.ctrlKey or $event.metaKey)       # detect S key pressed and either OSX Command or Window's Control keys pressed
      @.$rootScope.$broadcast '', $event                                  # broadcast keyup_CtrS event
      #$event.preventDefault()                                             # this should be used by the event listeners to prevent default browser behaviour

  setup_Hooks: ()=>
    angular.element(@.$window).bind "keydown", @.on_Key_Down              # hook keydown event in window (only called once per app load)
    @

app.service 'keyboard', ($injector)=>
  return new Keyboard($injector).setup_Hooks()