本文實例講述了JavaScript實現網頁對象拖放功能的方法。分享給大家供大家參考。具體如下：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Drag</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<style>
#myDiv{width:50px; height:50px; background-color:red}
</style>
</head>
<body>
<div id="myDiv"></div>
</body>
<script type="text/javascript">
var isIE = document.all ? true : false;
//判斷是否是IE浏覽器
function addEventHandler(oTarget, sEventType, fnHandler){
//添加事件
if(oTarget.addEventListener){
oTarget.addEventListener(sEventType, fnHandler, false);
}else if(oTarget.attachEvent){
oTarget.attachEvent("on" + sEventType, fnHandler);
}else{
oTarget["on" + sEventType] = fnHandler;
}
}
function removeEventHandler(oTarget, sEventType, fnHandler) {
//移除事件
if (oTarget.removeEventListener) {
oTarget.removeEventListener(sEventType, fnHandler, false);
} else if (oTarget.detachEvent) {
oTarget.detachEvent("on" + sEventType, fnHandler);
} else {
oTarget["on" + sEventType] = null;
}
}
var BindAsEventListener = function(object, fun) {
//以另一個對象替換當前對象
return function(event) {
return fun.call(object, (event || window.event));
}
}
var $ = function(id){
return document.getElementById(id);
}
var Class = {
create: function() {
return function() {this.initialize.apply(this, arguments);}
}
}
var drag = Class.create();
drag.prototype = {
initialize: function(id){//初始化
this._drag = $(id);
this._flag = false;
addEventHandler(this._drag,'mousedown',BindAsEventListener(this,this.start));
this._fM = BindAsEventListener(this, this.move);
this._fS = BindAsEventListener(this, this.stop);
this._drag.style.position = "absolute";
},
start: function(oEvent){//相當於onmousedown事件
//return this._name;
this._x = oEvent.clientX - this._drag.offsetLeft;
this._y = oEvent.clientY - this._drag.offsetTop;
addEventHandler(document, 'mousemove', this._fM);
addEventHandler(document, 'mouseup', this._fS);
if(isIE){
addEventHandler(this._drag, "losecapture", this._fS);
//焦點丟失
this._Handle.setCapture();//設置鼠標捕獲
}else{
addEventHandler(window, "blur", this._fS);//焦點丟失
oEvent.preventDefault();//阻止默認動作
}
},
move: function(oEvent){ //相當於onmonusemove事件
this._drag.style.left = oEvent.clientX - this._x + "px";
this._drag.style.top = oEvent.clientY - this._y + "px";
},
stop: function(){ //相當於onmouseup事件
removeEventHandler(document, 'mousemove', this._fM);
removeEventHandler(document, 'mouseup', this._fS);
if(isIE){
removeEventHandler(this._drag, "losecapture", this._fS);
this._Handle.releaseCapture();
}else{
removeEventHandler(window, "blur", this._fS);
}
}
}
var ndrag = new drag("myDiv");
</script>
</html>
希望本文所述對大家的javascript程序設計有所幫助。