A thought on input js

Fragment of inut.js

"use strict";
	var Input = {};
    
    var functions = {
        'mousedown' : [],
        'mouseup': [],
        'mousemove': [],
        'keyup': [],
        'keydown': [],
        'mousewheel': []
    }
    //Suscribe
	Input.on = function(name, fn){
        if(!functions[name]){
            return false;
        }
        functions[name].push(fn);
    }
    //Unsuscribe
    Input.off = function(name, fn){
        var index = functions[name].indexOf(fn);
        functions[name].splice(index,1);
    }
    
    //Event listeners
	document.documentElement.addEventListener("mousedown", mouseDown, false);
	document.documentElement.addEventListener("mouseup", mouseUp, false);
	document.documentElement.addEventListener("mousemove", mouseMove, false);
	document.documentElement.addEventListener("keyup", keyUp, false);
	document.documentElement.addEventListener("keydown", keyDown, false);
	document.documentElement.addEventListener("mousewheel", mouseWheel, false);
	document.documentElement.addEventListener("DOMMouseScroll", mouseWheel, false); // Firefox
	
    //Triggers
	function mouseWheel(e){
        var index, mouseWheelDelta;
        mouseWheelDelta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));
		e = e || window.event;
        //Notify
        for(index =0; index<functions['mousewheel'].length; index++){
            functions['mousewheel'][index](mouseWheelDelta);
        }
	};

    function keyDown(e){
        var index,key;
		e = e || window.event;
		key = (typeof e.which === "undefined") ? e.keyCode : e.which;
		//Notify
        for(index =0; index<functions['keydown'].length; index++){
            functions['keydown'][index](key);
        }
	};
    
	function keyUp(e){
		var index,key;
		e = e || window.event;
		key = (typeof e.which === "undefined") ? e.keyCode : e.which;
		//Notify
        for(index =0; index<functions['keyup'].length; index++){
            functions['keyup'][index](key);
        }
	};

loadScene.js

  Input.touch = false;
  Input.mouse = true;
  Input.gamepad = false;
  
  //suscribe
  Input.on('click', myClickFunction);
  Input.on('keyup', myKeyPressFunction);
  Input.on('swipe', mySwipeFunction);
  
  Input.on('gamepadKey', myGamePadKeyPressFunction);
  //Unsuscribe
  Input.off('click', myClickFunction);
  
  
  function myKeyPressFunction(key){
    //Swithc case key and do functionality
    switch(key){
      case "w":
        //_---
      break;
      
    }
  }