Chrome web store download

chromwebstore.js

/*
 * @title crx DL link
 * @description prompt crx download-link on Chrome Web Store
 * @include https://chrome.google.com/webstore/detail/*
 * @contributor taizooo         http://let.hatelabo.jp/taizooo/let/gYC-x-e5r_G0bw (Fork of)
 * @contributor noromanba       http://let.hatelabo.jp/noromanba/let/hLHX5-ST-aMn
 * @license MIT License http://opensource.org/licenses/MIT
 * @javascript_url
 */

// http://stackoverflow.com/questions/7184793/how-to-download-a-crx-file-from-the-chrome-web-store-for-a-given-id
// http://0-9.tumblr.com/post/52782603407/chrome-extension-development-casual

(function () {
  // http://let.hatelabo.jp/noromanba/let/hLHVzOTQjfYH
  var canonical = function () {
      var url = (document.head.querySelector('meta[property="og:url"][content]') || {}).content ||
                (document.head.querySelector('link[rel="canonical"][href]') || {}).href ||
                location.href;
      // https://developer.mozilla.org/en-US/docs/Web/API/URL
      // https://developer.mozilla.org/en-US/docs/Web/API/URL.URL
      return new URL(url);
  };

  var id = canonical().pathname.split('/').filter(function (s) { return !!s; } ).pop();
  var link = [
    // can use https
    'http://clients2.google.com/service/update2/crx?response=redirect&x=id%3D',
    id,
    '%26uc',
    // 32 or higher e.g. 33, 64. OBSOLETE "&prod=chrome"
    '&prodversion=32'
  ].join('');

  prompt('Copy Me', link);
})();

// dev-doc https://gist.github.com/noromanba/5776183