JavaScript中實現拖放功能的示範代碼

最後更新：2018-12-04 來源：互聯網

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注意：以下代碼在Windows下的IE中得到良好的支援,以外的瀏覽器不一定支援。

先來看拖動項事件，代碼如下：

說明：

當某個項被拖動時，會依次觸發以下事件：

(1)dragstart

(2)drag

(3)dragend

接著來看放置目標事件：

說明：

事件觸發順序為：

(1)dragenter

(2)ondragover

若最終移除目標項觸發

(3)ondragleave

成功移入則觸發

(4)ondrop

建立自己的放置目標：

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleDragDropEvent(oEvent) { var oTextbox = document.getElementById("txt1"); oTextbox.value += oEvent.type + "/n"; //建立自己的放置目標 switch(oEvent.type) { case "dragover": case "dragenter": oEvent.returnValue = false; } //建立自己的放置目標 } </script> </head> <body> Try dragging the text from the textbox to the red square. Drop target events fire now. <input type="text" value="drag this text" ondragstart="handleDragDropEvent(event)" ondrag="handleDragDropEvent(event)" ondragend="handleDragDropEvent(event)" /> <div style="background-color: red; height: 100px; width: 100px" ondragenter="handleDragDropEvent(event)" ondragover="handleDragDropEvent(event)" ondragleave="handleDragDropEvent(event)" ondrop="handleDragDropEvent(event)"></div> <textarea rows="10" cols="25" readonly="readonly" id="txt1"></textarea> </body> </html>

再來研究下資料轉送對象:dataTransfer

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleDragDropEvent(oEvent) { switch(oEvent.type) { case "dragover": case "dragenter": oEvent.returnValue = false; break; case "drop": alert(oEvent.dataTransfer.getData("text")); } } </script> </head> <body> Try dragging the text from the textbox to the red square. It will show you the selected text when dropped. <input type="text" value="drag this text" /> <div style="background-color: red; height: 100px; width: 100px" ondragenter="handleDragDropEvent(event)" ondragover="handleDragDropEvent(event)" ondrop="handleDragDropEvent(event)"></div> </body> </html>

再看一下例子：

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleDragDropEvent(oEvent) { switch(oEvent.type) { case "dragover": case "dragenter": oEvent.returnValue = false; break; case "drop": alert(oEvent.dataTransfer.getData("URL")); } } </script> </head> <body> Try dragging the link to the red square. It will show you the URL when dropped. <a href="http://www.wrox.com" target="_blank">Wrox Home Page</a> <div style="background-color: red; height: 100px; width: 100px" ondragenter="handleDragDropEvent(event)" ondragover="handleDragDropEvent(event)" ondrop="handleDragDropEvent(event)"></div> </body> </html>

最後再看看真正的拖動實現代碼：

1.資料拖動

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleDragDropoEvent(oEvent) { switch(oEvent.type) { case "dragstart": oEvent.dataTransfer.effectAllowed = "move"; break; case "dragenter": oEvent.dataTransfer.dropEffect = "move"; break; case "dragover": oEvent.returnValue = false; break; case "drop": oEvent.returnValue = false; oEvent.srcElement.innerHTML = oEvent.dataTransfer.getData("text"); } } </script> </head> <body> Try dragging the text in the textbox to the red square. The text will be "moved" to the red square. <input type="text" value="drag this text" ondragstart="handleDragDropoEvent(event)" /> <div style="background-color: red; height: 100px; width: 100px" ondragenter="handleDragDropoEvent(event)" ondragover="handleDragDropoEvent(event)" ondrop="handleDragDropoEvent(event)"></div> </body> </html>

2.資料拷貝

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleDragDropEvent(oEvent) { switch(oEvent.type) { case "dragstart": oEvent.dataTransfer.effectAllowed = "copy"; break; case "dragenter": oEvent.dataTransfer.dropEffect = "copy"; oEvent.returnValue = false; break; case "dragover": oEvent.returnValue = false; break; case "drop": oEvent.returnValue = false; oEvent.srcElement.innerHTML = oEvent.dataTransfer.getData("text"); } } </script> </head> <body> Try dragging the text in the textbox to the red square. The text will be "copied" to the red square. <input type="text" value="drag this text" ondragstart="handleDragDropEvent(event)" /> <div style="background-color: red; height: 100px; width: 100px" ondragenter="handleDragDropEvent(event)" ondragover="handleDragDropEvent(event)" ondrop="handleDragDropEvent(event)"></div> </body> </html>

3.dragDrop方法示範(可用於幾乎所有的HTML元素)

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleMouseMove(oEvent) { if (oEvent.button == 1) { oEvent.srcElement.dragDrop(); } } function handleDragDropEvent(oEvent) { oEvent.dataTransfer.setData("text", "This is a red square"); } </script> </head> <body> Try dragging the red square into the textbox. <div style="background-color: red; height: 100px; width: 100px" onmousemove="handleMouseMove(event)" ondragstart="handleDragDropEvent(event)">This is a red square</div> <input type="text" value="" /> </body> </html>

4.URL拖動至瀏覽器URL並跳轉

<html> <head> <title>System Drag And Drop Example</title> <script type="text/javascript"> function handleMouseMove(oEvent) { if (oEvent.button == 1) { oEvent.srcElement.dragDrop(); } } function handleDragDropEvent(oEvent) { oEvent.dataTransfer.setData("URL", "http://www.wrox.com/"); } </script> </head> <body> Try dragging the red square into another browser window. <div style="background-color: red; height: 100px; width: 100px" onmousemove="handleMouseMove(event)" ondragstart="handleDragDropEvent(event)">http://www.wrox.com</div> </body> </html>

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