Drag and Drop

Drag and drop is a very common feature. It is when you "grab" an object and drag it to a different location.

In HTML5, drag and drop is part of the standard: Any element can be draggable.

Drag the W3Schools image into the rectangle:
     

Make an Element Draggable

First of all: To make an element draggable, set the draggable attribute to true: 

What to Drag - ondragstart and setData()

Then, specify what should happen when the element is dragged.

In the example above, the ondragstart attribute calls a function, drag(event), that specifies what data to be dragged.

The dataTransfer.setData() method sets the data type and the value of the dragged data:

function drag(ev) {  ev.dataTransfer.setData("text", ev.target.id);}

In this case, the data type is "text" and the value is the id of the draggable element ("drag1").

Where to Drop - ondragover

The ondragover event specifies where the dragged data can be dropped.

By default, data/elements cannot be dropped in other elements. To allow a drop, we must prevent the default handling of the element.

This is done by calling the event.preventDefault() method for the ondragover event

Do the Drop - ondrop

When the dragged data is dropped, a drop event occurs.

In the example above, the ondrop attribute calls a function, drop(event):

function drop(ev) {  ev.preventDefault();  var data = ev.dataTransfer.getData("text");  ev.target.appendChild(document.getElementById(data));}

Code explained:

• Call preventDefault() to prevent the browser default handling of the data (default is open as link on drop)
• Get the dragged data with the dataTransfer.getData() method. This method will return any data that was set to the same type in the setData() method
• The dragged data is the id of the dragged element ("drag1")
• Append the dragged element into the drop element

Drag and Drop
Drag the image back and forth between the two div elements.
         
  
          
         
         

 

 

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