gitlab-org--gitlab-foss/app/assets/javascripts/behaviors/copy_to_clipboard.js

import Clipboard from 'clipboard';

function showTooltip(target, title) {
  const $target = $(target);
  const originalTitle = $target.data('original-title');

  if (!$target.data('hideTooltip')) {
    $target
      .attr('title', title)
      .tooltip('fixTitle')
      .tooltip('show')
      .attr('title', originalTitle)
      .tooltip('fixTitle');
  }
}

function genericSuccess(e) {
  showTooltip(e.trigger, 'Copied');
  // Clear the selection and blur the trigger so it loses its border
  e.clearSelection();
  $(e.trigger).blur();
}

/**
 * Safari > 10 doesn't support `execCommand`, so instead we inform the user to copy manually.
 * See http://clipboardjs.com/#browser-support
 */
function genericError(e) {
  let key;
  if (/Mac/i.test(navigator.userAgent)) {
    key = '⌘'; // Command
  } else {
    key = 'Ctrl';
  }
  showTooltip(e.trigger, `Press ${key}-C to copy`);
}

export default function initCopyToClipboard() {
  const clipboard = new Clipboard('[data-clipboard-target], [data-clipboard-text]');
  clipboard.on('success', genericSuccess);
  clipboard.on('error', genericError);

  /**
   * This a workaround around ClipboardJS limitations to allow the context-specific copy/pasting
   * of plain text or GFM. The Ruby `clipboard_button` helper sneaks a JSON hash with `text` and
   * `gfm` keys into the `data-clipboard-text` attribute that ClipboardJS reads from.
   * When ClipboardJS creates a new `textarea` (directly inside `body`, with a `readonly`
   * attribute`), sets its value to the value of this data attribute, focusses on it, and finally
   * programmatically issues the 'Copy' command, this code intercepts the copy command/event at
   * the last minute to deconstruct this JSON hash and set the `text/plain` and `text/x-gfm` copy
   * data types to the intended values.
   */
  $(document).on('copy', 'body > textarea[readonly]', (e) => {
    const clipboardData = e.originalEvent.clipboardData;
    if (!clipboardData) return;

    const text = e.target.value;

    let json;
    try {
      json = JSON.parse(text);
    } catch (ex) {
      return;
    }

    if (!json.text || !json.gfm) return;

    e.preventDefault();

    clipboardData.setData('text/plain', json.text);
    clipboardData.setData('text/x-gfm', json.gfm);
  });
}