Essayez-le vous-même - JavaScript Reference ondragstart

<!DOCTYPE HTML>
<html>
<head>
<style>
.droptarget {
   float: left;
   width: 100px;
   height: 35px;
   margin: 15px;
   padding: 10px;
   border: 1px solid #aaaaaa;
}
</style>
</head>
<body>

<p>This example uses the HTML DOM to assign "ondragstart", "ondragend", "ondragover" and "ondrop" events to the document object.</p>

<p>Drag the p element back and forth between the two rectangles:</p>

<div class="droptarget">
  <p draggable="true" id="dragtarget">Drag me!</p>
</div>

<div class="droptarget"></div>

<p style="clear:both;"><strong>Note:</strong> drag events are not supported in Internet Explorer 8 and earlier versions or Safari 5.1 and earlier versions.</p>

<p id="demo"></p>

<script>
/* Events fired on the drag target */
document.ondragstart = function(event) {
   event.dataTransfer.setData("Text", event.target.id);
   document.getElementById("demo").innerHTML = "Started to drag the p element.";
};

document.ondragend = function(event) {
   document.getElementById("demo").innerHTML = "Finished dragging the p element.";
};

/* Events fired on the drop target */
document.ondragover = function(event) {
   event.preventDefault();
};

document.ondrop = function(event) {
   event.preventDefault();
   if ( event.target.className == "droptarget" ) {
   var data = event.dataTransfer.getData("Text");
   event.target.appendChild(document.getElementById(data));
   }
};
</script>

</body>
</html>

<p>This example uses the HTML DOM to assign "ondragstart", "ondragend", "ondragover" and "ondrop" events to the document object.</p>

<p>Drag the p element back and forth between the two rectangles:</p>

<p style="clear:both;"><strong>Note:</strong> drag events are not supported in Internet Explorer 8 and earlier versions or Safari 5.1 and earlier versions.</p>

document.ondragend = function(event) {
    document.getElementById("demo").innerHTML = "Finished dragging the p element.";
};

/* Events fired on the drop target */
document.ondragover = function(event) {
    event.preventDefault();
};

document.ondrop = function(event) {
    event.preventDefault();
    if ( event.target.className == "droptarget" ) {
        var data = event.dataTransfer.getData("Text");
        event.target.appendChild(document.getElementById(data));
    }
};
</script>

</body>
</html>