No need for jQuery inside of an iframe

app/assets/javascripts/embed.js

@@ -1,2 +1,3 @@
-//= require base
+//= require es5-shim.min
+//= require console-shim-min
 //= require asciinema-player

app/helpers/asciicasts_helper.rb

@@ -9,6 +9,7 @@ module AsciicastsHelper
 
   def player_tag(asciicast, options, skip_titlebar)
     opts = {
+      id: 'player',
       src: asciicast.url,
       cols: asciicast.width,
       rows: asciicast.height,

app/views/api/asciicasts/show.html.slim

@@ -4,18 +4,21 @@ p.powered
   a href=root_url target="_top" asciinema
 
 javascript:
-  $(function() {
+
+  var player = document.getElementById('player');
+
+  player.addEventListener('attached', function() {
     var target = parent.postMessage ? parent : (parent.document.postMessage ? parent.document : undefined);
     if (typeof target != "undefined" && window !== window.parent) {
-      var w = $('.asciinema-player').width();
-      var h = $(document).height();
+      var w = player.getElementsByClassName('asciinema-player')[0].offsetWidth;
+      var h = Math.max(document.body.scrollHeight, document.body.offsetHeight);
       target.postMessage(['asciicast:size', { width: w, height: h }], '*');
     }
 
     function onMessage(e) {
       var event = e.data[0];
       if (event == 'asciicast:play') {
-        $('.start-prompt').click();
+        // player.play(); // TODO
       }
     }