Simple keycode object collection for Javascript

Ofcourse, this game also has to respond to the keyboard. I got tired of looking up keycodes real quick and decided to just create an associative array out of them, for the hell of it. My IDE even autocompletes them. Here's the list:

// A var storing all useful keys for easy access
var key = {
    'Backspace': 8,
    'Tab': 9,
    'Enter': 13,
    'Shift': 16,
    'Ctrl': 17,
    'Alt': 18,
    'Pause': 19,
    'Capslock': 20,
    'Esc': 27,
    'Pageup': 33,
    'Pagedown': 34,
    'End': 35,
    'Home': 36,
    'Leftarrow': 37,
    'Uparrow': 38,
    'Rightarrow': 39,
    'Downarrow': 40,
    'Insert': 45,
    'Delete': 46,
    '0': 48,
    '1': 49,
    '2': 50,
    '3': 51,
    '4': 52,
    '5': 53,
    '6': 54,
    '7': 55,
    '8': 56,
    '9': 57,
    'a': 65,
    'b': 66,
    'c': 67,
    'd': 68,
    'e': 69,
    'f': 70,
    'g': 71,
    'h': 72,
    'i': 73,
    'j': 74,
    'k': 75,
    'l': 76,
    'm': 77,
    'n': 78,
    'o': 79,
    'p': 80,
    'q': 81,
    'r': 82,
    's': 83,
    't': 84,
    'u': 85,
    'v': 86,
    'w': 87,
    'x': 88,
    'y': 89,
    'z': 90,
    '0numpad': 96,
    '1numpad': 97,
    '2numpad': 98,
    '3numpad': 99,
    '4numpad': 100,
    '5numpad': 101,
    '6numpad': 102,
    '7numpad': 103,
    '8numpad': 104,
    '9numpad': 105,
    'Multiply': 106,
    'Plus': 107,
    'Minut': 109,
    'Dot': 110,
    'Slash1': 111,
    'F1': 112,
    'F2': 113,
    'F3': 114,
    'F4': 115,
    'F5': 116,
    'F6': 117,
    'F7': 118,
    'F8': 119,
    'F9': 120,
    'F10': 121,
    'F11': 122,
    'F12': 123,
    'equal': 187,
    'Coma': 188,
    'Slash': 191,
    'Backslash': 220
}

Now you can use things like "key.Uparrow" in your code in stead of it's corresponding number. For example:

// Bind the onKeyDown function to the onkeydown event.
window.onkeydown = onKeyDown;

/**
 *This function is called whenever a key is pressed on the keyboard
 *@param    key     {int}   The key
 */
function onKeyDown(keypress) {

    // Select the correct key and execute its functions
    switch (keypress.keyCode) {

        case key.Uparrow:
            // Do  something
            break;

        case key.Rightarrow:
            // Do  something
            break;

        case key.Downarrow:
            // Do  something
            break;

        case key.Leftarrow:
            // Do something
            break;
    }
}