DataTransferItemList.add

The DataTransferItemList.add() method creates a new DataTransferItem using the specified data and adds it to the drag data list. The item may be a File or a string of a given type. If the item is successfully added to the list, the newly-created DataTransferItem object is returned.

Syntax

DataTransferItem = DataTransferItemList.add(data, type);
DataTransferItem = DataTransferItemList.add(file);

Parameters

data

A string representing the drag item's data.

type

A string of the drag item's type. Some example types are text/html and text/plain.

file

A File object. No type needs to be given in this case.

Return value

A DataTransferItem containing the specified data. If the drag item couldn't be created (for example, if the associated DataTransfer object has no data store), null is returned.

Exceptions

NotSupportedError

A string data parameter was provided, and the list already contains an item whose kind is "Plain Unicode string" and whose type is equal to the specified type parameter.

Example

This example shows the use of the add() method.

HTML

<div>
 <p id="source" ondragstart="dragstart_handler(event);" ondragend="dragend_handler(event);" draggable="true">
 Select this element, drag it to the Drop Zone and then release the selection to move the element.</p>
</div>
<div id="target" ondrop="drop_handler(event);" ondragover="dragover_handler(event);">Drop Zone</div>

CSS

div {
  margin: 0em;
  padding: 2em;
}
#source {
  color: blue;
  border: 1px solid black;
}
#target {
  border: 1px solid black;
}

Javascript

function dragstart_handler(ev) {
  console.log("dragStart");
  // Add this element's id to the drag payload so the drop handler will
  // know which element to add to its tree
  var dataList = ev.dataTransfer.items;
  dataList.add(ev.target.id, "text/plain");
  // Add some other items to the drag payload
  dataList.add("<p>... paragraph ...</p>", "text/html");
  dataList.add("http://www.example.org","text/uri-list");
}

function drop_handler(ev) {
  console.log("Drop");
  ev.preventDefault();
  var data = event.dataTransfer.items;
  // Loop through the dropped items and log their data
  for (var i = 0; i < data.length; i++) {
    if ((data[i].kind == 'string') && (data[i].type.match('^text/plain'))) {
      // This item is the target node
      data[i].getAsString(function (s){
        ev.target.appendChild(document.getElementById(s));
      });
    } else if ((data[i].kind == 'string') && (data[i].type.match('^text/html'))) {
      // Drag data item is HTML
      data[i].getAsString(function (s){
        console.log("... Drop: HTML = " + s);
      });
    } else if ((data[i].kind == 'string') && (data[i].type.match('^text/uri-list'))) {
      // Drag data item is URI
      data[i].getAsString(function (s){
        console.log("... Drop: URI = " + s);
      });
    }
  }
}

function dragover_handler(ev) {
  console.log("dragOver");
  ev.preventDefault();
  // Set the dropEffect to move
  ev.dataTransfer.dropEffect = "move"
}

function dragend_handler(ev) {
  console.log("dragEnd");
  var dataList = ev.dataTransfer.items;
  for (var i = 0; i < dataList.length; i++) {
    dataList.remove(i);
  }
  // Clear any remaining drag data
  dataList.clear();
}

Result

Result link

Specifications

Specification	Status	Comment
WHATWG HTML Living Standard The definition of 'add()' in that specification.	Living Standard
HTML5.1 The definition of 'add()' in that specification.	Recommendation	Not included in W3C HTML5 Recommendation

Browser compatibility