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Cross-browser drag and drop

, 21 Apr 2012
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This article explains how to make drag and drop work across multiple browsers.

Introduction

I could not find a good Drag and Drop JavaScript example that would work in all browsers (including iPad). So I wrote one myself. I hope someone might find it useful. Please note that this example shows how to “capture” the element so that you don’t lose it if you move outside of the element or outside of the browser window.

Unfortunately, I could not find a good way how not to lose capture over an iFrame in Chrome and Safari. The best approach I found is to cover all iFrames with DIVs while the dragging is taking place. Any suggestions on how to do this better are welcome.

This article is for those that like nuts and bolts and are not using third party libraries like jQuery. There is nothing wrong with using third party libraries – I just like more flexibility. For example, you can use this example to resize elements.

Using the code

To use this script, use the MakeDragable JavaScript function. It accepts only one parameter: the ID of the element you want users to drag. Here is the full JavaScript code:


var oDragItem = null;
var iClickOffsetX = 0;
var iClickOffsetY = 0;

function OnLoad(){
	MakeDragable("idBox1");
	MakeDragable("idBox2");	
}

function MakeDragable(id){
	var oBox = $(id);
	oBox.className = "Dragable";
	
	if (navigator.platform=="iPad"){
		oBox.ontouchstart= function(e){TouchStart(e)};
		oBox.ontouchmove=function(e){TouchMove(e)};
	}else{
		oBox.onmousemove= function(e){DragMove(oBox,e)};
		oBox.onmouseup=function(e){DragStop(oBox,e)};
		oBox.onmousedown=function(e){DragStart(oBox,e);return false};	
	}	
}

function TouchStart(e){
	var oPos = GetObjPos(e.target);
	iClickOffsetX = e.targetTouches[0].pageX - oPos.x;
	iClickOffsetY = e.targetTouches[0].pageY - oPos.y;
}

function DragStart(o,e){
	if(!e) var e = window.event;
	oDragItem = o;
	
	if (e.offsetX){
		iClickOffsetX = e.offsetX;
		iClickOffsetY = e.offsetY;	
	}else{
		var oPos = GetObjPos(o);
		iClickOffsetX = e.clientX - oPos.x;
		iClickOffsetY = e.clientY - oPos.y;
	}
	
	if (o.setCapture){
		o.setCapture();
	}else{
		window.addEventListener ("mousemove", DragMove2, true);
		window.addEventListener ("mouseup",   DragStop2, true);
	}
}

function DragMove2(e){
	DragMove(oDragItem,e);
}

function DragStop2(e){
	DragStop(oDragItem,e);
}

function DragMove(o,e){
	if (oDragItem==null) return;

	if(!e) var e = window.event;
	var x = e.clientX + document.body.scrollLeft - document.body.clientLeft - iClickOffsetX;
	var y = e.clientY + document.body.scrollTop  - document.body.clientTop - iClickOffsetY;
	
	with(oDragItem.style){
		zIndex = 1000;
		position="absolute";
		left=x;
		top=y;
	}
}

function TouchMove(e){
    e.preventDefault();
    var curX = e.targetTouches[0].pageX - iClickOffsetX;
    var curY = e.targetTouches[0].pageY - iClickOffsetY; 
    
    var o = e.targetTouches[0].target;
    o.style.position = "absolute";
    o.style.top  = curY + 'px'; 
    o.style.left = curX + 'px'; 
}

function DragStop(o,e){
	if (oDragItem==null) return;

	if (o.releaseCapture){
		o.releaseCapture();
	}else if (oDragItem){
		window.removeEventListener ("mousemove", DragMove2, true);
		window.removeEventListener ("mouseup",   DragStop2, true);
	}
	
	oDragItem.style.zIndex = 1;
	oDragItem = null;
}

function $(s){
	return document.getElementById(s);
}

function GetObjPos(obj){
	var x = 0;
	var y = 0;
	
	var w = obj.offsetWidth;
	var h = obj.offsetHeight;
	if (obj.offsetParent) {
		x = obj.offsetLeft
		y = obj.offsetTop
		while (obj = obj.offsetParent){
			x += obj.offsetLeft;
			y += obj.offsetTop;
		}
	}
	return {x:x, y:y, w:w, h:h};
}


I created a single CSS class to make drag-able elements not selectable and to have the cursor suggest that the element is drag-able.

<style>
.Dragable
{
   cursor:move;
   -moz-user-select: -moz-none;   
   -khtml-user-select: none;   
   -webkit-user-select: none;   
   -o-user-select: none;   
   user-select: none;
}

Points of Interest

I also wrote a related article called: JavaScript example of drag and drop to a target

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Igor Krupitsky
Web Developer
United States United States
Igor is a business intelligence consultant working in Tampa, Florida. He has a BS in Finance from University of South Carolina and Masters in Information Management System from University of South Florida. He also has following professional certifications: MCSD, MCDBA, MCAD.

Comments and Discussions

 
QuestionDrag & Drop of an audio file PinmemberMember 109960636-Aug-14 7:29 
QuestionAndroid Pinmemberwerd6-Jul-12 5:42 
GeneralMy vote of 5 PinmemberIvan Stefanov18-Jul-11 22:17 
GeneralRe: My vote of 5 Pinmembersecorbett21-Jul-11 2:16 
GeneralRe: My vote of 5 PinmemberIgor Krupitsky16-Aug-11 13:22 
GeneralMy vote of 3 Pinmembersecorbett18-Jul-11 9:12 
SuggestionGood Attempt - but why not jQuery? PinmemberrManiks15-Jul-11 4:05 
GeneralRe: Good Attempt - but why not jQuery? Pinmembersecorbett18-Jul-11 9:12 
I have to agree with this. jQuery is the most popular framework that has cross-browser support for drag and drop. There are a number of others as well.
Scott E. Corbett
Software Engineer/Analyst

GeneralRe: Good Attempt - but why not jQuery? PinmemberDewey20-Jul-11 22:52 
GeneralRe: Good Attempt - but why not jQuery? Pinmembersecorbett21-Jul-11 2:14 
GeneralRe: Good Attempt - but why not jQuery? PinmemberDewey20-Jul-11 22:50 
GeneralRe: Good Attempt - but why not jQuery? PinmemberHaBiX24-Jul-11 23:11 
GeneralRe: Good Attempt - but why not jQuery? Pinmemberwerd6-Jul-12 5:20 
GeneralRe: Good Attempt - but why not jQuery? Pinmemberwerd6-Jul-12 5:25 
GeneralRe: Good Attempt - but why not jQuery? PinmemberSinned Lolwut12-Aug-14 9:32 

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