HTML ondrop Event Attribute

Description

The ondrop HTML event attribute fires when a draggable element or text selection is dropped on a valid drop target. Drag and drop is a common feature in HTML5 that allows users to move elements around a web page or between web pages.

To make an element draggable, you can use the draggable attribute. Links and images are draggable by default.

The ondrop event attribute takes a JavaScript function as its value. This function will be executed when the draggable element or text selection is dropped on the drop target.

Here is an example of how to use the ondrop event attribute:

<div id="drop-target" ondrop="myFunction(event)">
  Drop your element here!
</div>

<script>
function myFunction(event) {
  // Get the element that was dropped.
  var droppedElement = event.target;

  // Get the drop target.
  var dropTarget = event.currentTarget;

  // Do something with the dropped element and the drop target.
  // For example, you could move the dropped element to the drop target.
}
</script>

The ondrop event attribute is a powerful tool that can be used to create interactive and user-friendly web applications.

Here are some examples of how the ondrop event attribute can be used:

To allow users to upload files by dragging and dropping them onto a web page.
To create a drag-and-drop sorting feature.
To create a drag-and-drop image gallery.
To create a drag-and-drop form builder.

In HTML5, seven event attributes were added that are used at various stages of the drag and drop operation:

Events that occur with the drag object:

ondragstart (triggered at the beginning of an item drag operation).
ondrag (triggered when an item is dragged).
ondragend (triggered when the user has finished dragging and dropping the item).

Events that occur with the object being dragged onto:

ondragenter (when the item will be transferred to the specified zone (target for transfer)).
ondragover (triggered when an element is moved over a valid transfer zone).
ondragleave (triggered when an element leaves an acceptable zone for transfer).
ondrop (triggered after the dragged item descends on the drag object).

Syntax

<element ondrop="script">

Values

scriptThe name of the script to use when the event has been triggered.

Example

Consider an example in which the <p> element can be moved between two <div> blocks. To do this, we will set four event attributes on the <div> blocks and three on the moveable <p> paragraph.

When we start moving the <p> element, two events are triggered: the first is triggered at the beginning of the operation of dragging the element with the mouse (ondragstart), on which we installed a script that allows you to store data and its type (setData method), the second ondrag event fires at the moment the drag started and informs us of this in the <p id="info"> </p> element.

By default, items cannot be placed in other items. To make this accessible (canceling the default browser) we use the preventDefault() method, which is triggered when an element is moved over a valid zone for transfer (the ondragover event attribute)

ondragenter event occurs when the element is moved to the specified zone, and a script is triggered that sets the background color to yellow and the dashed border to black. When an element leaves a given zone, the border and background style values are returned to their original form (ondragleave event)

The example uses two more event attributes: the first is ondrop, which is triggered when an element descends onto a drag object, a script is launched that allows you to receive data (getData method) and the second attribute of events is ondragend, which is triggered when the user has finished dragging and dropping the element and runs a script that informs us about the completion of the drag and drop procedure in the <p id="info"> </p> element.

HTML

<!DOCTYPE html> 

  <html> 

  <head>

    <title>Attributes for mouse events.  Drag and drop.</title> 

    <style> 

    .dragndrop {

      width: 200px;

      height: 50px;

      border: 3px solid orange;

      padding: 30px;

      text-align: center;

      background: cornsilk;

      float: left;

      margin-right: 20px;

    }

    </style> 

  </head> 

  <body> 

  <p>Move the HTML &lt;p&gt; element between the two rectangles:</p> 

  <div class="dragndrop" ondragenter="dragEnter(event)" ondragleave="dragLeave(event)" ondrop="drop(event)" ondragover="allowDrop(event)"> 

  <p ondragstart="dragStart(event)" ondrag="dragging(event)" ondragend="dragEnd(event)" draggable="true" id="anyid">Move me!</p> 

  </div> 

  <div class="dragndrop" ondragenter="dragEnter(event)" ondragleave="dragLeave(event)" ondrop="drop(event)" ondragover="allowDrop(event)"> </div> 

  <p id="info"> </p> 

<script>

function dragStart ( event ) { 

  event.dataTransfer.setData( "Text" , event.target.id);  

} 

function dragging ( event ) { 

  document.getElementById("info").innerHTML = "The &lt;p&gt; element is being dragged (ondrag)"; 

} 

function allowDrop ( event ) { 

  event.preventDefault();  

} 

function dragEnter ( event ) { 

  if (event.target.className == "dragndrop") { 

    event.target.style.background = "yellow"; 

    event.target.style.border = "3px dotted black"; 

  } 

} 

function dragLeave ( event ) { 

  if (event.target.className == "dragndrop") { 

    event.target.style.background = ""; 

    event.target.style.border = ""; 

  } 

} 

function drop ( event ) { 

  var data = event.dataTransfer.getData ("Text");

  event.target.appendChild(document.getElementById(data));

} 

function dragEnd ( event ) { 

  document.getElementById("info").innerHTML="Draggable &lt;p&gt; element dropped onto the drag object (ondragend)"; 

}

</script> 

  </body> 

</html>