HTML 5 drag events | 易学教程

问题

I am trying to build a reorderable list in JS and HTML. (trying to do it without using jQuery ui ) I can't seem to figure out why only the dragstart and dragend events fire when a list item is dragged. Anyone know why the other events not firing?

<ul>
    <li draggable="true" class="drag">1111111</li>
    <li draggable="true" class="drag">222222</li>
    <li draggable="true" class="drag">333333</li>
    <li draggable="true" class="drag">444444</li>
</ul>

<script type="text/javascript">
    var drags = document.querySelectorAll('.drag');
    [].forEach.call(drags, function(drag) {
      drag.addEventListener('dragstart', handleDragStart, false);
      drag.addEventListener('dragenter', handleDragEnter, false);
      drag.addEventListener('dragover', handleDragOver, false);
      drag.addEventListener('dragleave', handleDragLeave, false);
      drag.addEventListener('dragend', handleDragEnd, false);
    });

    function handleDragStart(e){
        console.log('handleDragStart');
    }

    function handleDragEnter(e){
        console.log('handleDragEnter');
    }

    function handleDragOver(e){
        console.log('handleDragOver');
    }

    function handleDragLeave(e){
        console.log('handleDragLeave');
    }

    function handleDragEnd(e){
        console.log('handleDragEnd');
    }
</script>

回答1:

As others have mentioned it already works in Chrome. In Firefox you need to set dataTransfer on dragstart and you need to do an e.preventDefault() to make elements valid drop targets. After that everything starts working:

var drags = document.querySelectorAll('.drag');
[].forEach.call(drags, function(drag) {
  drag.addEventListener('dragstart', handleDragStart, false);
  drag.addEventListener('dragenter', handleDragEnter, false);
  drag.addEventListener('dragover', handleDragOver, false);
  drag.addEventListener('dragleave', handleDragLeave, false);
  drag.addEventListener('dragend', handleDragEnd, false);
  drag.addEventListener('drop', handleDragEnd, false);
});

function handleDragStart(e) {
  console.log('dragstart ' + e.target.innerText);
  e.dataTransfer.setData('text/plain', 'This text may be dragged')
}

function handleDragEnter(e) {
  console.log('dragenter ' + e.target.innerText);
  e.preventDefault();
}

function handleDragOver(e) {
  console.log('dragover ' + e.target.innerText);
  e.preventDefault();
}

function handleDragLeave(e) {
  console.log('dragleave ' + e.target.innerText);
}

function handleDragEnd(e) {
  console.log('dragend ' + e.target.innerText);
  e.preventDefault();
}

<div draggable="true" class="drag">AAAAAA</div>
<div draggable="true" class="drag">BBBBBB</div>
<div draggable="true" class="drag">CCCCCC</div>
<div draggable="true" class="drag">DDDDDD</div>
<div draggable="true" class="drag">EEEEEE</div>

Note: I also added a drop handler so that Firefox wouldn't try to load a URL when you drop something.

回答2:

Using IE 10 works fine.

I recommend using jQuery UI, it's very, very simple and works in all browsers: http://jqueryui.com/demos/sortable/

来源：https://stackoverflow.com/questions/11529788/html-5-drag-events

标签

javascript

html

dom-events