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JavaScript implements the drag and drop function of web objects

  • 2020-05-30 19:22:45
  • OfStack

This article illustrates how JavaScript implements the drag-and-drop function of web objects. Share with you for your reference. The details are as follows: 


<!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;
 // Judge whether IE The browser 
 function addEventHandler(oTarget, sEventType, fnHandler){
 // Add event 
 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) {
 // Remove event 
 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) {
 // On the other 1 Replace the current object with three objects 
 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){// Initialize the 
 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){// The equivalent of onmousedown The event 
 //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);
 // Lost focus 
  this._Handle.setCapture();// Set mouse capture 
 }else{
  addEventHandler(window, "blur", this._fS);// Lost focus 
  oEvent.preventDefault();// Block default action 
 }
 },
 move: function(oEvent){ // The equivalent of onmonusemove The event 
 this._drag.style.left = oEvent.clientX - this._x + "px";
 this._drag.style.top = oEvent.clientY - this._y + "px";
 },
 stop: function(){ // The equivalent of onmouseup The event 
 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>

I hope this article has been helpful to your javascript programming.

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