(function (window, document, drawModule, undefined) { var btn = document.getElementById('btn'); btn.addEventListener("click", function(){ drawModule.init();}); document.onkeydown = function(event) { keyCode = window.event.keyCode; keyCode = event.keyCode; switch(keyCode) { case 37: if (direction != 'right') { direction = 'left'; } console.log('left'); break; case 39: if (direction != 'left') { direction = 'right'; console.log('right'); } break; case 38: if (direction != 'down') { direction = 'up'; console.log('up'); } break; case 40: if (direction != 'up') { direction = 'down'; console.log('down'); } break; } } })(window, document, drawModule);