Facebook Javascript SDK の読み込みと初期化速度を測定

    var millsec = 0;
    function logging(message) {
      $("#log").append("
log : " + message + ": wait " + (+new Date() - millsec).toString() + " millisecond
");
    }
    function initFacebookAPI(loadedHandler) {
      millsec = +new Date();
      window.fbAsyncInit = function() {
        logging("start fbAsyncInit");
        FB.init({
          xfbml: false,
          version: 'v2.7'
        });
        logging("finish fbAsyncInit");
        loadedHandler();
      };
      (function(d, s, id) {
        logging("facebook-jssdk");
        var js, fjs = d.getElementsByTagName(s)[0];
        if (d.getElementById(id)) {
          return;
        }
        js = d.createElement(s);
        js.id = id;
        js.src = "https://connect.facebook.net/en_US/sdk.js";
        fjs.parentNode.insertBefore(js, fjs);
      }(document, 'script', 'facebook-jssdk'));
    }
    initFacebookAPI(
      function() {
        document.getElementById('show-fb-share-button').onclick = function() {
          millsec = +new Date();
          logging("start FB.XFBML.parse");
          FB.XFBML.parse(document.body, function() {
            logging("finish FB.XFBML.parse");
          });
        };
      }
    );