Javascript 事件对象进阶（一）拖拽的原理

时间：2014-06-21 00:41:56 收藏：0 阅读：269

拖拽原理

鼠标和Div的相对距离不变
三大事件
把拖拽加到document上

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style>
#div1 {width: 100px; height: 100px; background: red; position: absolute;}
</style>
<script>
window.onload = function() {
	
	/*
	onmousedown : 选择元素
	onmousemove : 移动元素
	onmouseup 	: 释放元素
	*/
	
	var oDiv = document.getElementById(‘div1‘);
	
	oDiv.onmousedown = function(ev) {
		var ev = ev || event;
		
		var disX = ev.clientX - this.offsetLeft;
		var disY = ev.clientY - this.offsetTop;
		
		document.onmousemove = function(ev) {
			var ev = ev || event;
			
			oDiv.style.left = ev.clientX - disX + ‘px‘;
			oDiv.style.top = ev.clientY - disY + ‘px‘;
			
		}
		
		document.onmouseup = function() {
			document.onmousemove = document.onmouseup = null;
		}
		
	}
	
}
</script>
</head>

<body>
	<div id="div1"></div>
    <div style="width: 100px; height: 100px; background: green; position: absolute; left: 400px; top: 200px;"></div>
</body>
</html>

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