Enhance links to other languages on Wikipedia

wikipedia_language_labels.user.js

// ==UserScript==
// @name        Wikipedia Language Labels
// @description Enhance interlanguage links on the sidebar (e.g. Change "Français" to "Étoile (Français)" on https://en.wikipedia.org/wiki/Star )
// @match       https://*.wikipedia.org/wiki/*
// @grant       none
// @version     2
// @noframes
// ==/UserScript==

// Original: https://gist.github.com/maripo/3925496

/*
    Customize labels by editing LABEL_STYLE.
    "${LABEL}", "${LANG_CODE}" and "${LANG_NAME}" will be replaced.

    e.g.
        "${LABEL} (${LANG_NAME})" => "Étoile (Français)"
        "[${LANG_CODE}]${LABEL}" => "[fr]Étoile"
 */

const LABEL_STYLE = '${LABEL} (${LANG_NAME})';

const links = document.querySelectorAll('#p-lang .interlanguage-link > a');
for (let link of links) {
  link.textContent = LABEL_STYLE.replace(/\${(\w+)}/g, (body, key) => {
    switch (key) {
    case 'LABEL':
      return decodeURIComponent(link.pathname.substring(6)).replace(/_/g, ' ');
    case 'LANG_CODE':
      return link.lang;
    case 'LANG_NAME':
      return link.textContent;
    default:
      return body;
    }
  });
}