JavaScript实现坦克移动小游戏：图片旋转与键盘控制

var current = 180;//需要反转的角度
tank.style.transform = 'rotate('+current+'deg)';//在style里的transform赋值'rotate('+current+'deg)'

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>Document</title>
</head>
<body>
 <div id='container'>
  <img src="tank.png" alt="" id='tank'>
 </div>
</body>
<script>
 container.style="width:1000px;height:800px;border:3px solid;";
 tank.style="width:200px;height:200px;position:relative;top:0px;left:0px;"
 document.body.onkeydown=function(){
  var current = 0;
  var top = parseInt(tank.style.top);
  var left = parseInt(tank.style.left);
  var code = event.keyCode;
  if(code == 37) {
   current = 180;
   tank.style.transform = 'rotate('+current+'deg)';
   if(left <= 0) {
    alert("您已经到最左边了！");
   }
   else{
    tank.style.left = (left-10) +"px";
   }
  }
  if(code == 38) {
   current =270;
   tank.style.transform = 'rotate('+current+'deg)';
   if(top <= 0) {
    alert("您已经到最上边了！");
   }
   else{
    tank.style.top = (top-10) +"px";
   }
  }
  if(code == 39) {
   current = 0;
   tank.style.transform = 'rotate('+current+'deg)';
   if(left+parseInt(tank.width)+6 >= 1000) {
    alert("您已经到最右边了！");
   }
   else{
    tank.style.left = (left+10) +"px";
   }
  }
  if(code == 40) {
   current = 90;
   tank.style.transform = 'rotate('+current+'deg)';
   if(top+parseInt(tank.width)+6 >= 800) {
    alert("您已经到最下边了！");
   }
   else{
    tank.style.top = (top+10) +"px";
   }
  }
 }
</script>
</html>