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JS碰撞检测

程序员文章站 2022-03-13 12:29:47
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<head>
	<meta charset="UTF-8">
	<title></title>
	<style type="text/css">
		#all{
			width: 500px;
			height: 500px;
			border: 2px solid sandybrown;
			position: relative;
			margin: 0 auto;
		}
		#div1{
			width: 50px;
			height: 50px;
			background-color: red;
			position: absolute;
		}
		#center{
			width: 150px;
			height: 150px;
			background-color: black;
			position: absolute;
			margin: 175px;
		}
	</style>
</head>
<body>
	<div id="all">
		<div id="div1"></div>
		<div id="center"></div>
	</div>
	<script type="text/javascript">
		var oAll  = document.getElementById("all");
		var oDiv1 = document.getElementById("div1");
		var oCenter = document.getElementById("center");
		
		var maxL = oAll.clientWidth - oDiv1.clientWidth;
		var maxT = oAll.clientHeight - oDiv1.clientHeight;
		
		oDiv1.onmousedown = function(){
			var ev = ev || window.event;
			var lessX = ev.clientX - oDiv1.offsetLeft;
			var lessY = ev.clientY - oDiv1.offsetTop;
			document.onmousemove = function(){
				var ev = ev || window.event;
				var posL = ev.clientX - lessX;
				var posT = ev.clientY - lessY;
				
				if(oCenter.offsetLeft-oDiv1.offsetWidth<posL && posL<325 && oCenter.offsetLeft-oDiv1.offsetWidth<posT && posT<325 ){
					oCenter.style.backgroundColor = "red"
				}else{
					oCenter.style.backgroundColor = "black"
				}
				if(posL<0){
					posL = 0;
				}
				if(posT<0){
					posT = 0;
				}
				if(posL>maxL){
					posL = maxL;
				}
				if(posT>maxT){
					posT = maxT;
				}
				oDiv1.style.left = posL + "px";
				oDiv1.style.top = posT + "px";
			}
		}
		document.onmouseup = function(){
			document.onmousemove = null;
			oDiv1.onmousemove = null;
		}
	</script>
</body>