键盘事件: onkeydown-按键被按下 onkeyup按键被松开 键盘事件一般都会绑定给一些可以获取到焦点的对象或者是document 按键控制div移动 ``` <div id="box1" style="width: 100px;height: 100px; background-color: aquamarine;position: absolute;"></div> <script type="text/javascript"> window.onload=function(){ var speed=10; var dir=0; setInterval(function(){ switch(dir){ case 37: //左 box1.style.left=box1.offsetLeft-speed+"px"; break; case 39: //右 box1.style.left=box1.offsetLeft+speed+"px"; break; case 38: //上 box1.style.top=box1.offsetTop-speed+"px"; break; case 40: //下 box1.style.top=box1.offsetTop+speed+"px"; break; } },100) document.onkeydown=function(event){ event=event||window.event; //当按下ctrl键时加快速度 if (event.ctrlKey) { speed=500; }else{ speed=10; } console.log(event.keyCode) dir=event.keyCode; } document.onkeyup=function(event){ dir=0; } } </script> ```