在Web開發(fā)中，我們要實現(xiàn)拖放效果，需要借助Javascript。今天讓我們使用Html5實現(xiàn)它：

先看html核心代碼:

代碼如下:

<div>

<p>把黃色小方塊拖入到紅色大方框中</p>

</div>

<div id="item" draggable="true">

</div>

<div id="drop">

</div>

draggable屬性是html5新增加的，它有三個值true,false,auto. true是可以拖，false是不可以，auto由用戶瀏覽器是否支持而定。更多請可以參考官方文檔.

加上一點兒樣式:

代碼如下:

<style type="text/css">

#drop

{

width: 300px;

height: 200px;

background-color: #ff0000;

padding: 5px;

border: 2px solid #000000;

}

#item

{

width: 100px;

height: 100px;

background-color: #ffff00;

padding: 5px;

margin: 20px;

border: 1px dashed #000000;

}

*[draggable=true] {

-moz-user-select:none;

-khtml-user-drag: element;

cursor: move;

}

*:-khtml-drag {

background-color: rgba(238,238,238, 0.5);

}

</style>

然后我們來看javascript:

代碼如下:

function listenEvent(eventTarget, eventType, eventHandler) {

if (eventTarget.addEventListener) {

eventTarget.addEventListener(eventType, eventHandler,false);

} else if (eventTarget.attachEvent) {

eventType = "on" + eventType;

eventTarget.attachEvent(eventType, eventHandler);

} else {

eventTarget["on" + eventType] = eventHandler;

}

}

// cancel event

function cancelEvent (event) {

if (event.preventDefault) {

event.preventDefault();

} else {

event.returnValue = false;

}

}

// cancel propagation

function cancelPropagation (event) {

if (event.stopPropagation) {

event.stopPropagation();

} else {

event.cancelBubble = true;

}

}

window.onload=function() {

var target = document.getElementById("drop");

listenEvent(target,"dragenter",cancelEvent);

listenEvent(target,"dragover", dragOver);

listenEvent(target,"drop",function (evt) {

cancelPropagation(evt);

evt = evt || window.event;

evt.dataTransfer.dropEffect = 'copy';

var id = evt.dataTransfer.getData("Text");

target.appendChild(document.getElementById(id));

});

var item = document.getElementById("item");

item.setAttribute("draggable", "true");

listenEvent(item,"dragstart", function(evt) {

evt = evt || window.event;

evt.dataTransfer.effectAllowed = 'copy';

evt.dataTransfer.setData("Text",item.id);

});

};

function dragOver(evt) {

if (evt.preventDefault) evt.preventDefault();

evt = evt || window.event;

evt.dataTransfer.dropEffect = 'copy';

return false;

}

由上面的代碼我們看使用一組HTML5 提供的拖放Events,直接來看下面:

dragstart

Drag event starts.

drag

During the drag operation.

dragenter

Drag is over the target; used to determine if target will accept drop.

dragover

Drag is over target; used to determine feedback to user.

drop

Drop occurs.

dragleave

Drag leaves target.

dragend

Drag operation ends.

定義了相關(guān)的事件，來實現(xiàn)想要功能。上面的Js不難看懂。

你可以自己試一下，目前在Opera支持最好，IE效果并不好。

希望對您Web開發(fā)有幫助.