js代码

<script>
	var fly=document.createElement('div');
	fly.id='fly';
	fly.style.width='60px';
	fly.style.height='60px';
	document.body.appendChild(fly);
	var skyx=0;
	var skyt=0;
	var c;
	var j;
	document.onmousemove=function(e){
		var fly=document.getElementById('fly');
		var contentx=fly.offsetLeft+fly.offsetWidth/2;
		var contenty=fly.offsetTop+fly.offsetHeight/2;
		var dx=e.clientX-contentx;
		var dt=e.clientY-contenty;
		c=Math.atan2(dx,dt);//取值
		c=180*c/Math.PI;//转换角度
		c=c*-1;//console.log(c);
		function to(){//飞机运动
			clearTimeout(j);
			fly.style.transform='rotate('+c+'deg)';
			switch(true){
				case c<15&&c>-15://向下飞
					skyt-=5;
					document.body.style.backgroundPositionY=skyt+'px';
					break;
				case c>15&&c<75://向左下角飞
					skyx+=3;
					skyt-=3;
					document.body.style.backgroundPositionX=skyx+'px';
					document.body.style.backgroundPositionY=skyt+'px';
					break;
				case c>75&&c<105://向左飞
					skyx+=5;
					document.body.style.backgroundPositionX=skyx+'px';
					break;
				case c>105&&c<165://向左上角飞
					skyx+=3;
					skyt+=3;
					document.body.style.backgroundPositionX=skyx+'px';
					document.body.style.backgroundPositionY=skyt+'px';
					break;
				case c>165||c<-165://向上飞
					skyt+=5;
					document.body.style.backgroundPositionY=skyt+'px';
					break;
				case c<-15&&c>-75://向右下角飞
					skyx-=3;
					skyt-=3;
					document.body.style.backgroundPositionX=skyx+'px';
					document.body.style.backgroundPositionY=skyt+'px';
					break;
				case c<-75&&c>-105://向右飞
					skyx-=5;
					document.body.style.backgroundPositionX=skyx+'px';
					break;
				case c<-105&&c>-165://向右上角飞
					skyx-=3;
					skyt+=3;
					document.body.style.backgroundPositionX=skyx+'px';
					document.body.style.backgroundPositionY=skyt+'px';
					break;
			}
			j=setTimeout(to,10);
		}
		to();
	}
</script>