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js面向对象练习（一）：拖曳效果
html:
<!DOCTYPE html>
<html>
<head>
<meta charset= "utf-8">
<title></title>
<!--<script src="http://www.mamicode.com/jquery-1.9.1.min.js"></script>-->
<style>
#drag{
background: red;
width: 200px;
height: 200px;
cursor: move;
position: fixed;
top: 0;
left: 0;
}
</style>
</head>
<body>
<div id="drag"></div>
<script src="http://www.mamicode.com/scripts/test.js"></script>
</body>
</html>js:
window.onload = function(){
var drag = new Drag("drag");
drag.init();
}
//获取浏览器窗口宽度
function getInner(){
var pageWidth = window.innerWidth;
var pageHeight = window.innerHeight;
if(typeof pageWidth != "number"){
if(document.compatMode == "CSS1Compat"){
pageWidth = document.documentElement.clientWidth;
pageHeight = document.documentElement.clientHeight;
}else {
pageWidth = document.body.clientWidth;
pageHeight = document.body.clientHeight;
}
}
return {width:pageWidth,height:pageHeight};
}
//构造函数
function Drag(id){
this.obj = document.getElementById("drag");
this.disx = 0;
this.disy = 0;
}
Drag.prototype.init = function(){
//this 指针
var me = this;
this.obj.||event;
me.onmouseDown(e);
//阻止默认事件
return false;
}
}
Drag.prototype.onmouseDown = function(e){
//this指针
var me = this;
this.disx = e.clientX - this.obj.offsetLeft;
this.disy = e.clientY - this.obj.offsetTop;
document.||event;
me.onmouseMove(e);
}
document.onmouseup = function(){
me.mouseUp();
}
}
Drag.prototype.onmouseMove = function (e){
//this指针
var lf = e.clientX - this.disx;
var tp = e.clientY - this.disy;
if(lf < 0){ //防止拖曳层超出左边界
lf = 0;
}else if(lf > getInner().width - this.obj.offsetWidth){
lf = getInner().width - this.obj.offsetWidth;//防止拖曳层超出右边界
}
if(tp < 0){
tp = 0;//防止拖曳层超出上边界
}else if(tp > getInner().height - this.obj.offsetHeight){
tp = getInner().height - this.obj.offsetHeight;//防止拖曳层超出下边界
}
this.obj.style.left = lf + ‘px‘;
this.obj.style.top = tp + ‘px‘;
};
Drag.prototype.mouseUp = function (){
document.onmousemove = null;
document.onmouseup = null;
};js面向对象练习（一）：拖曳效果
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