Helper to register keyboard events by named functions. Simple at the moment, could do with some more keywords.

onKeyboard.js

(function(window, factory) {
	var onKeyboard = factory(window, window.document);
	window.onKeyboard = onKeyboard;
	if(typeof module == 'object' && module.exports){
		module.exports = onKeyboard;
	}
})(window, function(window, document) {

	// var keycodes = {
	// 	left: 37,
	// 	right: 39,
	// 	up: 38,
	// 	down: 40,
	// 	escape: 27
	// };

	var _getProp = function( prop, obj ) {

	    if ( obj.hasOwnProperty( prop ) ) {
	        return obj[prop];
	    } else {
	        return undefined;
	    }

	};


	var keycodes = [
		['left', 37],
		['right', 39],
		['up', 38],
		['down', 40],
		['escape', 2]
	];



	var OnKeyboard = function( options ) {
		var self = this;

		self._options = options;
		self._active = true;
		self.fire = {};


		keycodes.forEach(function( k ) {

			var n = k[1];
			var c = k[0];


			var cb = _getProp( c, self._options )

			if (typeof cb === 'function') {
				self.fire[ c ] = function( e, isMetaKey ) {
					if ( self._active ) {
						cb( e, isMetaKey );
					}
				};
			} else {
				self.fire[ c ] = false;
			}


		});


		document.addEventListener( 'keydown', function(e) {

			keycodes.forEach(function( k ) {

				var n = k[1];
				var c = k[0];

				if ( n === e.which && self.fire[c] ) {
					self.fire[ c ](e, e.metaKey );
				}

			});

		});
	};

	OnKeyboard.prototype.deactivate = function() {
		this._active = false;
	};

	OnKeyboard.prototype.activate = function() {
		this._active = true;
	};

	return OnKeyboard;


});