Hotkey.js

var Hotkey = (function(){
    var modifiers = ['ctrl', 'shift', 'alt'];
    var hotkeys = $H();
    return {
        add: function(keyCombination, behavior, options){
            var keys = keyCombination.split('+');
            var mods = keys.union(modifiers);
            var key = keys.without.apply(keys, modifiers).reduce();
            if(Object.isArray(key)) throw "Error: Hotkey can only contain one key that is not a modifier";
            
            options = Object.extend({
                element: document,
                bubble: false,
                retval: false
            }, options || {});
            
            hotkeys.set(keyCombination, {options: options, handler: { 
                keydown: function(event){
                    var triggered = Event.hasKeyEvent(Event['KEY_' + key.toUpperCase()])
                        || Event.hasKeyEvent(key.charCodeAt(0));
                    mods.each(function(mod){
                        triggered = triggered && event[mod + 'Key'];
                    });
                    
                    if(triggered) {
                        behavior(event);
                        if(!options.bubble) event.stopPropagation();
                        if(!options.retval) event.preventDefault();
                    }
                }
            }});
            
            options.element.observeAll(hotkeys.get(keyCombination).handler);
        },
        remove: function(keyCombination){
            var hotkey = hotkeys.get(keyCombination)
            hotkey.options.element.stopObservingAll(hotkey.handler);
        }
    };
})();