HTML5 Drag and Drop - Firefox is being redirected

Question

I'm trying to implement html5's drag and drop in my app but Firefox is always redirected to dropped image's source. I'm using e.stopPropagation(). In Chromium everything works as expected. Strange... Here's the code:

<html>
 <head>
  <meta charset="utf-8" />
  <title>DuOS 0.0.0</title>
  <meta name="author" content="Jan Durrer, Michal Grňo" />
  <link rel="stylesheet" href="./default.css" />
 </head>
 <body>
  <script src="./boot.js"></script>
  <script src="./window.js"></script>
  <script src="./omnibox.js"></script>
  <section class="desktop">
   <img class="icon" id="computer" style="left: 0px; top: 340px;" src="./image/icon/system/computer.png" />
   <img class="icon" id="folder" style="left: 0px; top: 170px;" src="./image/icon/system/documents.png" />
   <img class="icon" id="bin" style="left: 0px; top: 0px;" src="./image/icon/system/bin.png" />
  </section>
  <script>
   window.clickedIcons = Array();
   window.draggedIcon = {};
   window.draggedIcon.offset = Array();
   window.draggedIcon.element = null;

   //Pohybování
   function drag_start(e) {
    window.draggedIcon.element = e.target;
    event.dataTransfer.effectAllowed = 'copyMove';
    event.dataTransfer.setData('text/plain', 'hola'); //hack

    var style = window.getComputedStyle(event.target, null);
    window.draggedIcon.offset[0] = parseInt(style.getPropertyValue("left"),10) - event.clientX; console.log(window.draggedIcon.offset[0]);
    window.draggedIcon.offset[1] = parseInt(style.getPropertyValue("top" ),10) - event.clientY; console.log(window.draggedIcon.offset[1]);
    window.draggedIcon.element = event.target;
   }

   function drag_over(e) {
    e.preventDefault();
    return false;
   }

   function drop(e) {
    window.draggedIcon.element.style.left = (event.clientX + window.draggedIcon.offset[0]) + 'px';
    window.draggedIcon.element.style.top  = (event.clientY + window.draggedIcon.offset[1]) + 'px';
    window.draggedIcon.element.style.visibility = 'visible';
    window.draggedIcon.element = null;
    if(e.stopPropagation) {e.stopPropagation();}
    return false;
   }
   var xresult = document.evaluate('//body/*[@class="desktop"]/*[@class="icon"]', document, null, XPathResult.ANY_TYPE, null);
   var dm = xresult.iterateNext();
   while (dm) {
    dm.addEventListener('dragstart',drag_start,false);
    dm.addEventListener('click',click,false);
    dm = xresult.iterateNext();
   }

   document.body.addEventListener('dragover',drag_over,true);
   document.body.addEventListener('drop',drop,true);
  </script>
 </body>
</html>

Thanks for your help, m93a.

score 36 · Accepted Answer · edited Dec 03 '15 at 17:16

36

You need to prevent the default action:

function drop(e) {
    if(e.preventDefault) { e.preventDefault(); }
    if(e.stopPropagation) { e.stopPropagation(); }
    window.draggedIcon.element.style.left = (event.clientX + window.draggedIcon.offset[0]) + 'px';
    window.draggedIcon.element.style.top  = (event.clientY + window.draggedIcon.offset[1]) + 'px';
    window.draggedIcon.element.style.visibility = 'visible';
    window.draggedIcon.element = null;
    return false;
}

edited Dec 03 '15 at 17:16

Jondlm

8,484
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answered Jan 26 '13 at 22:29

robertc

72,359
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4

`preventDefault` does the job ! But could someone explain me why a drop would trigger a redirect on Firefox ?? – Matthieu Riegler Oct 22 '19 at 08:58
@MatthieuRiegler Wild guess: Dropping a file into Firefox navigates to the file, that's why the default is navigate to the URL being dropped. In my case, `drag` had called `event.dataTransfer.setData('text/plain', "css")` before and FF attempted to open the URL `"css"`. – awendt Apr 07 '21 at 07:41

HTML5 Drag and Drop - Firefox is being redirected

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