【问题标题】:Having trouble understanding why the boxes are not draggable无法理解为什么这些框不可拖动
【发布时间】:2014-09-16 16:09:41
【问题描述】:

我正在测试拖放元素。我打算稍后对其进行编辑以做其他事情。现在我在关注一本名为 Sams Teach Yourself HTML5 的书。我已经完全按照代码进行操作,但由于某种未知原因,它拒绝允许拖放工作。我使用了最新的 Internet Explorer Mozilla Firefox 和 Google Chrome。我尝试了大约 4 种不同的代码验证器,但均无济于事。

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>
Drage and Drop Example
</title>
<style type="text/css">
#target1, #target2, #target3
{
float: left; width: 250px; height: 250px;
padding: 10px; margin: 10px;
}
#draggable1, #draggable2, #draggable3
{
width: 75px; height: 70px; padding: 5px;
margin: 5px;
}
#target1{background-color: cyan;}
#target2{background-color: cyan;}
#target3{background-color: cyan;}
#draggable1{background-color: orange;}
#draggable2{background-color: orange;}
#draggable3{background-color: orange;}
</style>
<script type="text/javascript">
function start(e) 
{
 e.dataTransfer.effectAllowed='move';
 e.dataTransfer.setData("Data",
 e.target.getAttribute('id'));
 e.dataTransfer.setDragImage(e.target, 0,0);
 return true;
}
function enter(e) 
{
 return true;   
}  
function over(e) 
{
 var iddraggable =
 e.dataTransfer.getData("Data");
var id = e.target.getAttribute('id');
if(id =='target1')
 return false;
if((id =='target2')
&& iddraggable == 'draggable3')
return false;
else if(id =='target3')

&& (iddraggable == 'draggable1' ||

iddraggable =='draggable2'))
return false;   
else 
return true;  
}
function drop(e) 
{
 var iddraggable =
 e.dataTransfer.getData("Data");
 e.target.appendChild
 (document.getElementById(iddraggable)); 
 e.stopPropagation();
 return false;      
}

function end(e) 

{

 e.dataTransfer.clearData("Data");

 return true    

}

</script>

</head>

<body>

<div id="target1"

 ondragenter="return enter(event)"

 ondragover="return over(event)"

 ondrop="return drop(event)">

 <div id="draggable1" draggable="true"

 ondragstart="return start(event)"

 ondragend="return end(event)">1

</div>
<div id="draggable2" draggable="true"
ondragstart="return start(event)"
ondragend="return end(event)">2
</div>
<div id="draggable3" draggable="true"
ondragstart="return start(event)"
ondrag="return end(event)">3
</div>
</div>
<div id="target2"
ondragenter="return enter(event)"
ondragover="return over(event)"
ondrop="return drop(event)">
</div>
<div id="target3"
ondragenter="return enter(event)"
ondragover="return over(event)"
ondrop="return drop(event)">
</div>
</body>
</html>`

【问题讨论】:

    标签: javascript css html drag-and-drop draggable


    【解决方案1】:

    您在该行缺少一个起始括号:

    else if(id =='target3') &&
             (iddraggable == 'draggable1' || iddraggable =='draggable2'))
        return false;
    

    应该是这样的:

    else if((id =='target3') &&
               (iddraggable == 'draggable1' || iddraggable =='draggable2'))
        return false;
    

    这是您的代码:http://jsfiddle.net/p4hwqawL/2/
    (有点......仍然需要改进。但错误消失了)

    【讨论】:

    • 非常感谢。这几天一直在挠头,哈哈。刚看了书,里面也少了,哈哈
    • @NathanR.Watkins,只是一个提示...始终识别您的代码,然后更容易定位这样的错误.. ;)
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