Redirect static DocumentCloud asset links to the canonical HTML page

platformer.js

/*!
 * Platformer
 * Redirect static DocumentCloud asset links to the canonical HTML page.
 *
 * Say you're at `https://assets.documentcloud.org/documents/282753/lefler-thesis.pdf`
 * and you want to view the original DocumentCloud page for that document. Click your
 * Platformer bookmarklet. It transforms that URL to the URL for the original document
 * on documentcloud.org.
 *
 * To use, create a bookmark with the following address (sans backticks):
 * `javascript:(function(){var pattern=/^https?:\/\/(s3\.amazonaws\.com\/s3|s3|assets)\.documentcloud\.org\/documents\/([0-9]+)\/(pages\/)?(.+)(\-p([0-9]+)(\-([a-z]+))?)?\.([a-z]{3})$/,current=window.location.href,platformed=current.replace(pattern,"https://www.documentcloud.org/documents/$2-$4.html");current==platformed?alert("Hmm, we weren’t able to transform this URL. Please send it to the dev team for inspection."):window.location=platformed;})();`
 *
 * TODO:
 * - Make a GH page with link people can drag to their bookmark bar
 *
 * @license (c) 2016 Justin Reese, DocumentCloud
 * Platformer may be freely distributed under the MIT license.
 *
 */

var pattern    = /^https?:\/\/(s3\.amazonaws\.com\/s3|s3|assets)\.documentcloud\.org\/documents\/([0-9]+)\/(pages\/)?(.+)(\-p([0-9]+)(\-([a-z]+))?)?\.([a-z]{3})$/;
var current    = window.location.href;
var platformed = current.replace(pattern, 'https://www.documentcloud.org/documents/$2-$4.html');
if (current == platformed) {
  alert('Hmm, we weren’t able to transform this URL. Please send it to the dev team for inspection.');
} else {
  window.location = platformed;
}