通过JS实现判断碰撞的方法！

<p id="d1"></p>
<p id="d2"></p>

<style type="text/css">
		*{
			padding: 0px;
			margin: 0px;

		}
		#d1{
			width: 100px;
			height: 100px;
			background: red;
			position: absolute;
		}
		#d2{
			width: 200px;
			height: 200px;
			background: yellow;
			position: absolute;
			top: 200px;
			left: 400px;
			position: absolute;
		}
	</style>

<script type="text/javascript">
	p=document.querySelectorAll("p"); 
function hit(obj){
	obj.onmousedown=function(e){
		var e=e||window.event;
		var dX=e.offsetX;
		var dY=e.offsetY;
		document.onmousemove=function(e){
			var x=e.clientX;
			var y=e.clientY;
			obj.style.left=x-dX+"px";
			obj.style.top=y-dY+"px";
			if(p[0].offsetTop+p[0].offsetHeight>=p[1].offsetTop && p[0].offsetTop<=p[1].offsetTop+p[1].offsetHeight && p[0].offsetLeft+p[0].offsetWidth>=p[1].offsetLeft && p[0].offsetLeft<=p[1].offsetLeft+p[1].offsetWidth){
				console.log("你撞我了！再撞一个试试！")
			};
	}
	document.onmouseup=function(){
		document.onmousemove=null;
	}
}	
}
hit(p[0]);
hit(p[1]);
</script>