Recent releases of the Chromium engine have changed the behavior related to clipboard writing. While Firefox, Safari, and older versions of Chrome allowed clipboard writing only after explicit user action, new releases simply require opening a website for writing to occur. This behavior change in Chrome is explained by the need to read data from the clipboard when displaying the Google Doodle on the new tab page (instead of implementing a specific handling for this situation, Chromium simply allowed all websites to write to the clipboard without user activation).
The write capability works with the methods navigator.clipboard.write (example) and navigator.clipboard.writeText (example), which now do not take into account user activity on the page. For example, to write to the clipboard immediately after opening the site, it's enough to execute the following JavaScript code: navigator.clipboard.writeText('Hello from the web page.'); let type = 'text/plain'; let blob = new Blob(['Hello from web page'], { type }); let item = new ClipboardItem({ [type]: blob }); navigator.clipboard.write([item]);
Source: opennet.ru
