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How to implement drag and drop of images in HTML5

清浅
清浅Original
2018-11-27 14:54:106426browse

Today I will share with you the usage of drag and drop elements in HTML5. It has certain reference value and I hope it will be helpful to everyone.

[Recommended courses: HTML5 Tutorial##]

Drag (drag) and drop (drop) is a common HTML5 special effect on the page. What it means is to grab the object and then drag and drop it to another a location. In HTML5, any element can be dragged and dropped, so in the following article, I will tell you in detail how to achieve the drag effect through examples.

Knowledge points required for drag and drop effects

draggable

Specifies whether an element can be dragged Generally, links and pictures are draggable by default.

true: Specifies that the element is draggable.

false: Specifies that the element is not draggable.

auto: Use the browser’s default features.

Events triggered when dragging and dropping elements

ondragstart: Events triggered when dragging elements start

ondrag: Triggered when elements are being dragged Event

ondragend: Event triggered after the user completes dragging the element

Event triggered when the target is released

ondragenter: The dragged element enters Events triggered when dragging the range

ondragover: Indicates where the event is triggered when the dragged data is placed.

ondragleave: Event triggered when the dragged element leaves the drag range

ondrop: When the mouse leaves the drag and drop element

Case sharing: Place the picture into the box

(1) Set the element to be draggable

<img  id="drag1" src=images/1.jpg" draggable="true" alt="How to implement drag and drop of images in HTML5" >

(2) What happens when the element is dragged (drag)

dataTransfer: Save the dragged data


text is the data type, event.target.id is the data, assign the data to dataTransfer and save it.


function drag(event)
{
event.dataTransfer.setData("Text",event.target.id);
}

(3) Drag the element to the specified position (drop)


By default, the element cannot be dragged to another position, so you need to cancel the default For events, you need to use the preventDefault() method

The setData() method refers to the data type and value of the dragged data

The appendChild() method moves elements from one element to another.

function drop(event)
{
event.preventDefault();//取消浏览器的默认行为
var data=event.dataTransfer.getData("Text");//获取指定格式的数据
event.target.appendChild(document.getElementById(data));
}

Complete code

<body>
	<div id="box" ondrop="drop(event)" ondragover="allowDrop(event)"></div>
	<img  src="images/1.jpg" id="drag1" draggable="true" ondragstart="drag(event)" alt="How to implement drag and drop of images in HTML5" >
<script>
	function allowDrop(event)
        {
          event.preventDefault();//取消事件默认行为
            }
		//拖
		function drag(event){
		 event.dataTransfer.setData("Text",event.target.id)
		}
		//放
          function drop(event){
	event.preventDefault();
	var data=event.dataTransfer.getData("text");
	event.target.appendChild(document.getElementById(data))
}
</script>
</body>

Rendering

How to implement drag and drop of images in HTML5

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