The ClipboardItem interface of the Clipboard API represents a single item format, used when reading or writing data via the Clipboard API. That is clipboard.read() and clipboard.write() respectively.

The benefit of having the ClipboardItem interface to represent data, is that it enables developers to cope with the varying scope of file types and data easily.

Access to the contents of the clipboard is gated behind the Permissions API: The clipboard-write permission is granted automatically to pages when they are in the active tab. The clipboard-read permission must be requested, which you can do by trying to read data from the clipboard.

ClipboardItem()

Creates a new ClipboardItem object, with the MIME type as the key and Blob as the value.

This interface provides the following properties.

types Read only

Returns an Array of MIME types available within the ClipboardItem.

presentationStyle Read only

Returns one of the following: "unspecified", "inline" or "attachment".

This interface defines the following methods.

getType()

Returns a Promise that resolves with a Blob of the requested MIME type, or an error if the MIME type is not found.

Here we're writing a new ClipboardItem() to the clipboard by requesting a png image using the Fetch API, and in turn, the responses' blob() method, to create the new ClipboardItem.

async function writeClipImg() {
  try {
    const imgURL = "/myimage.png";
    const data = await fetch(imgURL);
    const blob = await data.blob();

    await navigator.clipboard.write([
      new ClipboardItem({
        [blob.type]: blob,
      }),
    ]);
    console.log("Fetched image copied.");
  } catch (err) {
    console.error(err.name, err.message);
  }
}

Here we're returning all items on the clipboard via the clipboard.read() method. Then utilizing the ClipboardItem.types property to set the getType() argument and return the corresponding blob object.

async function getClipboardContents() {
  try {
    const clipboardItems = await navigator.clipboard.read();

    for (const clipboardItem of clipboardItems) {
      for (const type of clipboardItem.types) {
        const blob = await clipboardItem.getType(type);
        // we can now use blob here
      }
    }
  } catch (err) {
    console.error(err.name, err.message);
  }
}

• Clipboard API
• Async Clipboard API demo on Glitch
• Image support for Async Clipboard article