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894

answers:

1

When testing a JavaScript in Firefox 3.5, I have access to constants such as KeyEvent.DOM_VK_D, but not in Google Chrome. Is there a cross-browser way of accessing these constants?

+6  A: 

You can define the KeyEvent object if it doesn’t exist:

if (typeof KeyEvent == "undefined") {
    var KeyEvent = {
        DOM_VK_CANCEL: 3,
        DOM_VK_HELP: 6,
        DOM_VK_BACK_SPACE: 8,
        DOM_VK_TAB: 9,
        DOM_VK_CLEAR: 12,
        DOM_VK_RETURN: 13,
        DOM_VK_ENTER: 14,
        DOM_VK_SHIFT: 16,
        DOM_VK_CONTROL: 17,
        DOM_VK_ALT: 18,
        DOM_VK_PAUSE: 19,
        DOM_VK_CAPS_LOCK: 20,
        DOM_VK_ESCAPE: 27,
        DOM_VK_SPACE: 32,
        DOM_VK_PAGE_UP: 33,
        DOM_VK_PAGE_DOWN: 34,
        DOM_VK_END: 35,
        DOM_VK_HOME: 36,
        DOM_VK_LEFT: 37,
        DOM_VK_UP: 38,
        DOM_VK_RIGHT: 39,
        DOM_VK_DOWN: 40,
        DOM_VK_PRINTSCREEN: 44,
        DOM_VK_INSERT: 45,
        DOM_VK_DELETE: 46,
        DOM_VK_0: 48,
        DOM_VK_1: 49,
        DOM_VK_2: 50,
        DOM_VK_3: 51,
        DOM_VK_4: 52,
        DOM_VK_5: 53,
        DOM_VK_6: 54,
        DOM_VK_7: 55,
        DOM_VK_8: 56,
        DOM_VK_9: 57,
        DOM_VK_SEMICOLON: 59,
        DOM_VK_EQUALS: 61,
        DOM_VK_A: 65,
        DOM_VK_B: 66,
        DOM_VK_C: 67,
        DOM_VK_D: 68,
        DOM_VK_E: 69,
        DOM_VK_F: 70,
        DOM_VK_G: 71,
        DOM_VK_H: 72,
        DOM_VK_I: 73,
        DOM_VK_J: 74,
        DOM_VK_K: 75,
        DOM_VK_L: 76,
        DOM_VK_M: 77,
        DOM_VK_N: 78,
        DOM_VK_O: 79,
        DOM_VK_P: 80,
        DOM_VK_Q: 81,
        DOM_VK_R: 82,
        DOM_VK_S: 83,
        DOM_VK_T: 84,
        DOM_VK_U: 85,
        DOM_VK_V: 86,
        DOM_VK_W: 87,
        DOM_VK_X: 88,
        DOM_VK_Y: 89,
        DOM_VK_Z: 90,
        DOM_VK_CONTEXT_MENU: 93,
        DOM_VK_NUMPAD0: 96,
        DOM_VK_NUMPAD1: 97,
        DOM_VK_NUMPAD2: 98,
        DOM_VK_NUMPAD3: 99,
        DOM_VK_NUMPAD4: 100,
        DOM_VK_NUMPAD5: 101,
        DOM_VK_NUMPAD6: 102,
        DOM_VK_NUMPAD7: 103,
        DOM_VK_NUMPAD8: 104,
        DOM_VK_NUMPAD9: 105,
        DOM_VK_MULTIPLY: 106,
        DOM_VK_ADD: 107,
        DOM_VK_SEPARATOR: 108,
        DOM_VK_SUBTRACT: 109,
        DOM_VK_DECIMAL: 110,
        DOM_VK_DIVIDE: 111,
        DOM_VK_F1: 112,
        DOM_VK_F2: 113,
        DOM_VK_F3: 114,
        DOM_VK_F4: 115,
        DOM_VK_F5: 116,
        DOM_VK_F6: 117,
        DOM_VK_F7: 118,
        DOM_VK_F8: 119,
        DOM_VK_F9: 120,
        DOM_VK_F10: 121,
        DOM_VK_F11: 122,
        DOM_VK_F12: 123,
        DOM_VK_F13: 124,
        DOM_VK_F14: 125,
        DOM_VK_F15: 126,
        DOM_VK_F16: 127,
        DOM_VK_F17: 128,
        DOM_VK_F18: 129,
        DOM_VK_F19: 130,
        DOM_VK_F20: 131,
        DOM_VK_F21: 132,
        DOM_VK_F22: 133,
        DOM_VK_F23: 134,
        DOM_VK_F24: 135,
        DOM_VK_NUM_LOCK: 144,
        DOM_VK_SCROLL_LOCK: 145,
        DOM_VK_COMMA: 188,
        DOM_VK_PERIOD: 190,
        DOM_VK_SLASH: 191,
        DOM_VK_BACK_QUOTE: 192,
        DOM_VK_OPEN_BRACKET: 219,
        DOM_VK_BACK_SLASH: 220,
        DOM_VK_CLOSE_BRACKET: 221,
        DOM_VK_QUOTE: 222,
        DOM_VK_META: 224
    };
}

See also KeyEvent in DOM Level 3.

Gumbo
So are the constants in Firefox's KeyEvent expected to be standard in future?
Liam
Will throw *ReferenceError* if `KeyEvent` doesn't exist. Use `typeof` instead.
kangax
@kangax Could you explain further please?
Liam
@Liam Sure. When `KeyEvent` is undeclared, a *ReferenceError* will be thrown. Checking with `typeof` avoids it - `if (typeof KeyEvent == 'undefined')`
kangax
@kangax Thanks, I didn't know how to use typeof.
Liam
Quite a few other people implmented similar things: http://trac.apostrophenow.org/browser/plugins/apostrophePlugin/branches/1.4/web/js/plugins/jquery.keycodes-0.2.js?rev=1839, http://github.com/annismckenzie/apostrophePlugin/blob/50706880249dee6f660840c98dca57685405afe7/rande/web/js/jquery.keycodes-0.2.js, http://github.com/drobati/django-homepage/blob/1a75e9ba31c24cb77d87ff3eb435333932056af7/media/js/jquery.keyNav.js, http://github.com/quafzi/timpany/blob/41e160d7f9ec820936e53dbeddb6c17465737f17/plugins/apostrophePlugin/web/js/plugins/jquery.keycodes-0.2.js
Daniel Ribeiro