The Clipboard API adds to the Navigator interface the read-only clipboard property, which returns the Clipboard object used to read and write the clipboard's contents.

The Clipboard API can be used to implement cut, copy, and paste features within a web application.

Use of the asynchronous clipboard read and write methods requires that the user grant the website or app permission to access the clipboard. This permission must be obtained from the Permissions API using the "clipboard-read" and/or "clipboard-write" permissions.

The Clipboard object used to access the system clipboard.

The following code uses navigator.clipboard to access the system clipboard in order to read the contents of the clipboard.

navigator.clipboard
  .readText()
  .then(
    (clipText) => (document.querySelector(".cliptext").innerText = clipText),
  );

This snippet replaces the contents of the element whose class is "cliptext" with the text contents of the clipboard. Perhaps this code is being used in a browser extension that displays the current clipboard contents, automatically updating periodically or when specific events fire.

If the clipboard is empty or doesn't contain text, the "cliptext" element's contents are cleared. This happens because readText() returns an empty string if the clipboard is empty or doesn't contain text.