DataTransferItemList

The DataTransferItemList object is a list of DataTransferItem objects representing items being dragged. During a drag operation, each DragEvent has a dataTransfer property and that property is a DataTransferItemList.

The individual items can be accessed using the bracket notation [].

DataTransferItemList was primarily designed for the HTML Drag and Drop API, and is still specified in the HTML drag-and-drop section, but it is now also used by other APIs, such as clipboardData and dataTransfer. Documentation of DataTransferItemList will primarily discuss its usage in drag-and-drop operations, and you should refer to the other APIs’ documentation for usage of DataTransferItemList in those contexts.

This interface has no constructor.

Instance properties

• length Read only
  • : An unsigned long that is the number of drag items in the list.

Instance methods

• add()
  • : Adds an item (either a File object or a string) to the drag item list and returns a DataTransferItem object for the new item.
• remove()
  • : Removes the drag item from the list at the given index.
• clear()
  • : Removes all of the drag items from the list.

Example

This example shows how to use drag and drop.

HTML

<div>
  <p id="source" 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">Drop Zone</div>

CSS

div {
  margin: 0em;
  padding: 2em;
}

#source {
  color: blue;
  border: 1px solid black;
}

#target {
  border: 1px solid black;
}

JavaScript

const source = document.getElementById("source");
const target = document.getElementById("target");

source.addEventListener("dragstart", (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
  const 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");
});

source.addEventListener("dragend", (ev) => {
  console.log("dragEnd");
  const dataList = ev.dataTransfer.items;

  // Clear any remaining drag data
  dataList.clear();
});

target.addEventListener("drop", (ev) => {
  console.log("Drop");
  ev.preventDefault();

  // Loop through the dropped items and log their data
  for (const item of ev.dataTransfer.items) {
    if (item.kind === "string" && item.type.match(/^text\/plain/)) {
      // This item is the target node
      item.getAsString((s) => {
        ev.target.appendChild(document.getElementById(s));
      });
    } else if (item.kind === "string" && item.type.match(/^text\/html/)) {
      // Drag data item is HTML
      item.getAsString((s) => {
        console.log(`… Drop: HTML = ${s}`);
      });
    } else if (item.kind === "string" && item.type.match(/^text\/uri-list/)) {
      // Drag data item is URI
      item.getAsString((s) => {
        console.log(`… Drop: URI = ${s}`);
      });
    }
  }
});

target.addEventListener("dragover", (ev) => {
  console.log("dragOver");
  ev.preventDefault();

  // Set the dropEffect to move
  ev.dataTransfer.dropEffect = "move";
});

Result

Specifications

Browser compatibility