KeyEvent Object in Firefox
JavaScript FAQ |
Keyboard & Mouse Events FAQ
|
Question: Doesn't the browser provide predefined contstants with key code values that I
Answer:
Firefox browsers do provide the global KeyEvent object with a set of predefined constants reflecting
the set of keys on most widely used keyboards.
The constants are named DOM_VK_KEYNAME, with values
representing the keydown/keyup key codes for the respective keys.
For example, DOM_VK_SHIFT is 16, DOM_VK_ESCAPE is 27, etc.
If your target browser is Firefox, you can use these constants instead of numeric values in your
keydown/keyup event handlers. As of 2010, other major browsers do not support
the KeyEvent constants.
Some JavaScript programmers might want to reuse the KeyEvent object
even outside Firefox; technically, this is easy to do by including an additional .js file
that tests for the presence of the KeyEvent object in the user's browser,
and defines KeyEvent with all its hard-coded constants if
the browser does not support the object natively.
However, a problem with this approach is that different browsers are not guaranteed to
have exactly the same numeric values of key codes; in fact, there are quite a few
differences between key codes for the same keys across browsers.
For example, in Internet Explorer DOM_VK_SEMICOLON=59 will be useless
(and may cause bugs) because
the numeric value of the keydown/keyup event.keyCode for
the semicolon key in IE is 186, and not 59.
Thus, until all major browsers use a fully standardized set of key codes,
the straightforward reuse of KeyEvent constants across browsers does not help that much.
What are the KeyEvent constant values?
If you are using Firefox, you can easily print out all KeyEvent constants by executing this code
in your browser:
<pre><script>for (var k in KeyEvent) {
document.writeln('KeyEvent.' + k + ' = ' + KeyEvent[k]);
}
</script></pre>
Here is the list of KeyEvent constants obtained by running the above code in Firefox 3.6:
// KeyEvent constants in Firefox 3.6 KeyEvent.DOM_VK_CANCEL = 3 KeyEvent.DOM_VK_HELP = 6 KeyEvent.DOM_VK_BACK_SPACE = 8 KeyEvent.DOM_VK_TAB = 9 KeyEvent.DOM_VK_CLEAR = 12 KeyEvent.DOM_VK_RETURN = 13 KeyEvent.DOM_VK_ENTER = 14 KeyEvent.DOM_VK_SHIFT = 16 KeyEvent.DOM_VK_CONTROL = 17 KeyEvent.DOM_VK_ALT = 18 KeyEvent.DOM_VK_PAUSE = 19 KeyEvent.DOM_VK_CAPS_LOCK = 20 KeyEvent.DOM_VK_ESCAPE = 27 KeyEvent.DOM_VK_SPACE = 32 KeyEvent.DOM_VK_PAGE_UP = 33 KeyEvent.DOM_VK_PAGE_DOWN = 34 KeyEvent.DOM_VK_END = 35 KeyEvent.DOM_VK_HOME = 36 KeyEvent.DOM_VK_LEFT = 37 KeyEvent.DOM_VK_UP = 38 KeyEvent.DOM_VK_RIGHT = 39 KeyEvent.DOM_VK_DOWN = 40 KeyEvent.DOM_VK_PRINTSCREEN = 44 KeyEvent.DOM_VK_INSERT = 45 KeyEvent.DOM_VK_DELETE = 46 KeyEvent.DOM_VK_0 = 48 KeyEvent.DOM_VK_1 = 49 KeyEvent.DOM_VK_2 = 50 KeyEvent.DOM_VK_3 = 51 KeyEvent.DOM_VK_4 = 52 KeyEvent.DOM_VK_5 = 53 KeyEvent.DOM_VK_6 = 54 KeyEvent.DOM_VK_7 = 55 KeyEvent.DOM_VK_8 = 56 KeyEvent.DOM_VK_9 = 57 KeyEvent.DOM_VK_SEMICOLON = 59 KeyEvent.DOM_VK_EQUALS = 61 KeyEvent.DOM_VK_A = 65 KeyEvent.DOM_VK_B = 66 KeyEvent.DOM_VK_C = 67 KeyEvent.DOM_VK_D = 68 KeyEvent.DOM_VK_E = 69 KeyEvent.DOM_VK_F = 70 KeyEvent.DOM_VK_G = 71 KeyEvent.DOM_VK_H = 72 KeyEvent.DOM_VK_I = 73 KeyEvent.DOM_VK_J = 74 KeyEvent.DOM_VK_K = 75 KeyEvent.DOM_VK_L = 76 KeyEvent.DOM_VK_M = 77 KeyEvent.DOM_VK_N = 78 KeyEvent.DOM_VK_O = 79 KeyEvent.DOM_VK_P = 80 KeyEvent.DOM_VK_Q = 81 KeyEvent.DOM_VK_R = 82 KeyEvent.DOM_VK_S = 83 KeyEvent.DOM_VK_T = 84 KeyEvent.DOM_VK_U = 85 KeyEvent.DOM_VK_V = 86 KeyEvent.DOM_VK_W = 87 KeyEvent.DOM_VK_X = 88 KeyEvent.DOM_VK_Y = 89 KeyEvent.DOM_VK_Z = 90 KeyEvent.DOM_VK_CONTEXT_MENU = 93 KeyEvent.DOM_VK_NUMPAD0 = 96 KeyEvent.DOM_VK_NUMPAD1 = 97 KeyEvent.DOM_VK_NUMPAD2 = 98 KeyEvent.DOM_VK_NUMPAD3 = 99 KeyEvent.DOM_VK_NUMPAD4 = 100 KeyEvent.DOM_VK_NUMPAD5 = 101 KeyEvent.DOM_VK_NUMPAD6 = 102 KeyEvent.DOM_VK_NUMPAD7 = 103 KeyEvent.DOM_VK_NUMPAD8 = 104 KeyEvent.DOM_VK_NUMPAD9 = 105 KeyEvent.DOM_VK_MULTIPLY = 106 KeyEvent.DOM_VK_ADD = 107 KeyEvent.DOM_VK_SEPARATOR = 108 KeyEvent.DOM_VK_SUBTRACT = 109 KeyEvent.DOM_VK_DECIMAL = 110 KeyEvent.DOM_VK_DIVIDE = 111 KeyEvent.DOM_VK_F1 = 112 KeyEvent.DOM_VK_F2 = 113 KeyEvent.DOM_VK_F3 = 114 KeyEvent.DOM_VK_F4 = 115 KeyEvent.DOM_VK_F5 = 116 KeyEvent.DOM_VK_F6 = 117 KeyEvent.DOM_VK_F7 = 118 KeyEvent.DOM_VK_F8 = 119 KeyEvent.DOM_VK_F9 = 120 KeyEvent.DOM_VK_F10 = 121 KeyEvent.DOM_VK_F11 = 122 KeyEvent.DOM_VK_F12 = 123 KeyEvent.DOM_VK_F13 = 124 KeyEvent.DOM_VK_F14 = 125 KeyEvent.DOM_VK_F15 = 126 KeyEvent.DOM_VK_F16 = 127 KeyEvent.DOM_VK_F17 = 128 KeyEvent.DOM_VK_F18 = 129 KeyEvent.DOM_VK_F19 = 130 KeyEvent.DOM_VK_F20 = 131 KeyEvent.DOM_VK_F21 = 132 KeyEvent.DOM_VK_F22 = 133 KeyEvent.DOM_VK_F23 = 134 KeyEvent.DOM_VK_F24 = 135 KeyEvent.DOM_VK_NUM_LOCK = 144 KeyEvent.DOM_VK_SCROLL_LOCK = 145 KeyEvent.DOM_VK_COMMA = 188 KeyEvent.DOM_VK_PERIOD = 190 KeyEvent.DOM_VK_SLASH = 191 KeyEvent.DOM_VK_BACK_QUOTE = 192 KeyEvent.DOM_VK_OPEN_BRACKET = 219 KeyEvent.DOM_VK_BACK_SLASH = 220 KeyEvent.DOM_VK_CLOSE_BRACKET = 221 KeyEvent.DOM_VK_QUOTE = 222 KeyEvent.DOM_VK_META = 224
See also: