Javascript DOM ondragenter Event

Introduction

Execute a JavaScript when a draggable element enters a drop target:

Drag the p element back and forth between the two rectangles:

View in separate window 

<!DOCTYPE HTML>
<html>
<head>
<style>
.droptarget {//w  w w.j  av a2 s  . c  o  m
  float: left;
  width: 100px;
  height: 35px;
  margin: 15px;
  margin-right: 100px;
  padding: 10px;
  border: 1px solid #aaaaaa;
}
</style>
</head>
<body>
<div class="droptarget" 
     ondrop="drop(event)" 
     ondragenter="dragEnter(event)" 
     ondragleave="dragLeave(event)" 
     ondragover="allowDrop(event)">
  <p ondragstart="dragStart(event)" 
     draggable="true" 
     id="dragtarget">Drag me!</p>
</div>

<div class="droptarget" 
     ondragenter="dragEnter(event)" 
     ondragleave="dragLeave(event)" 
     ondrop="drop(event)" 
     ondragover="allowDrop(event)"></div>
<p id="demo"></p>

<script>
function dragStart(event) {
  event.dataTransfer.setData("Text", event.target.id);
}

function dragEnter(event) {
  if ( event.target.className == "droptarget" ) {
    document.getElementById("demo").innerHTML = "Entered the dropzone";
    event.target.style.border = "3px dotted red";
  }
}

function dragLeave(event) {
  if ( event.target.className == "droptarget" ) {
    document.getElementById("demo").innerHTML = "Left the dropzone";
    event.target.style.border = "";
  }
}

function allowDrop(event) {
  event.preventDefault();
}

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

</body>
</html>

The ondragenter event occurs when a draggable element or text selection enters a valid drop target.

To make an element draggable, use the global HTML5 draggable attribute.

Links and images are draggable by default, and do not need the draggable attribute.

Bubbles: Yes
Cancelable: Yes
Event type: DragEvent
Supported HTML tags: All HTML elements



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