Add RottenTomatoes ratings to Letterboxd film pages.

letterboxd-rt.js

// ==UserScript==
// @name         Letterboxd RT
// @namespace    http://barvian.me/
// @version      1.0.0
// @description  Add RottenTomatoes ratings to Letterboxd film pages.
// @author       Maxwell Barvian
// @match        *://letterboxd.com/*
// ==/UserScript==

(function(window, document, undefined) {
  var RT_API = "http://api.rottentomatoes.com/api/public/v1.0/",
    API_KEY = "uk8evfz8t2x6q8rzmyfqxc6n", // please replace this with your own
    stripIMDBID = /tt\d{7}/g;

  var rtResponseHandler = function(response) {
    if (response.readyState != 4)
      return;

    try {
      var film = JSON.parse(response.responseText);

      if (film.ratings.critics_rating || film.ratings.audience_rating) {
        var rtNode = document.createElement("section");
        rtNode.className = "section friends-watched rotten-tomatoes";
        rtNode.innerHTML += '<h2 class="section-heading"><a href="' + film.links.alternate + '">Rotten Tomatoes</a></h2>';
        rtNode.innerHTML += '<a href="' + film.links.alternate + '" class="has-icon icon-16 icon-more all-link"><span class="icon"></span>More</a>';
        if (film.ratings.critics_rating) {
          rtNode.innerHTML += '<p class="has-icon icon-16 icon-watched small-watched" style="display:block;"><span class="icon"></span> <a href="' + film.links.alternate + 'reviews/">' + film.ratings.critics_score + '%</a> ' + film.ratings.critics_rating + '</p>'
        }
        if (film.ratings.audience_rating) {
          rtNode.innerHTML += '<p class="has-icon icon-16 icon-watched small-watched" style="display:block;"><span class="icon"></span> <a href="' + film.links.alternate + 'reviews/?type=user">' + film.ratings.audience_score + '%</a> ' + film.ratings.audience_rating + '</p>'
        }

        sidebar.appendChild(rtNode);
      }
    } catch (e) {

    }
  };

  var sidebar = document.querySelector(".film .sidebar");
  if (sidebar) {
    // Retrieve IMDB ID of current film
    var imdbLink = document.querySelector(".col-main .text-link a[href*='imdb.com']");
    if (imdbLink) {
      var match = stripIMDBID.exec(imdbLink.getAttribute("href"));
      if (match && match.length == 1) {
        var imdbID = match[0].replace("tt", "");

        // Make RT API request using Alias API and IMDB ID
        GM_xmlhttpRequest({
          method: 'GET',
          url: RT_API + "movie_alias.json?type=imdb&id=" + imdbID + "&apikey=" + API_KEY,
          accept: 'text/json',
          onreadystatechange: rtResponseHandler
        });
      }
    }
  }
})(window, document);