I am going to fucking 🆁🅴🅳🅰🅲🆃🅴🅳 myself.

This example implements text copying when a data-copy attribute is added any HTML element such as a button. You can set this value to either of these:

1. a hard-coded string — such as data-copy="copy this to the clipboard".
2. a CSS selector — such as data-copy="#mysection". The text content of the first matching element is then copied.

Optionally, you can set a custom success message in a data-done attribute:

<button data-copy="#mysection" data-done="section copied">
  copy text from #mysection
</button>

The button is only shown when navigator.clipboard.writeText() is supported. When clicked, the JavaScript event handler locates the text, copies it to the clipboard, and shows an animated success message.

The text paste button is very similar except it defines a data-paste attribute which must point to a DOM node:

<textarea id="pastehere"></textarea>
<button data-paste="#pastehere">paste</button>

Copy and Paste Data

The Clipboard API’s readText() and writeText() are convenience options for the more generic read() and write() methods. These have less browser support but are able to copy and paste any type of data such as binary images.

Copying requires blob data typically returned by a fetch() or canvas.toBlob() method. This is passed to a ClipboardItem constructor so it can be written to the clipboard:

const
  image = await fetch('myimage.png'),
  blob = await image.blob();

await navigator.clipboard.write([
  new ClipboardItem({ [blob.type]: blob })
]);

Pasting is more complex because multiple ClipboardItem objects can be returned with differing content types. It’s therefore necessary to iterate through each type until a useful format is found. For example:

const clipboardItems = await navigator.clipboard.read();

for (const clipboardItem of clipboardItems) {
  for (const type of clipboardItem.types) {
    if (type === 'image/png') {
      // return PNG blob
      return await clipboardItem.getType(type);
    }
  }
}

Cut, Copy, and Paste Events

The cut, copy, and paste events fire whenever the user initiates a clipboard action in the browser — typically with right-click menus or the keyboard shortcuts mentioned above. This is supported in most browsers and handler functions can intercept the events to make changes using a `clipboardData object* passed as a parameter.

The following function forces all cut or copied text to be uppercase. Note that e.preventDefault() stops the default cut/copy action which would override it:

body.addEventListener('cut', cutCopyHandler);
body.addEventListener('copy', cutCopyHandler);

// cut or copy event handler
function cutCopyHandler(e) {

  const selection = document.getSelection();

  // send uppercase text to clipboard
  e.clipboardData.setData(
    'text/plain',
    selection.toString().toUpperCase()
  );

  if (e.type === 'cut') selection.deleteFromDocument();

  // stop default cut/copy
  e.preventDefault();

}

The following code attaches a paste handler to a specific <textarea> field. The function clears the existing content and prefixes the text "pasted:":

document.getElementById('field1').addEventListener('paste', pasteEvent);

// paste event handler
function pasteEvent(e) {

  // add 'pasted:' to pasted text
  const paste = 'pasted:\n' +
    (e.clipboardData || window.clipboardData).getData('text');

  e.target.value = paste;

  // stop default paste
  e.preventDefault();
}

This works in a similar way to the text demonstration, in that copy and paste buttons must point to DOM elements using a CSS selector in data-copyblob and data-pasteblob attributes. For example:

<!-- copy image -->
<img id="myimage" src="myimage.png" alt="any image" />

<button data-copyblob="#myimage" data-done="image copied">
  copy image
</button>

<!-- paste into DOM -->
<div id="imagelist"></div>

<button data-pasteblob="#imagelist">
  paste image
</button>

Try copying image data from a graphics application, then use the paste button.

How do you achieve this functionality under GNU/Linux operating systems?