  var msg = JSON.parse(event.data);
            if (msg == &quot;start&quot;) {
                body.innerHTML = &quot;&quot;;
                cells = {}
                return
            }
            var order    = msg[0];
            var contents = msg[1];
            for (var i = 0; i &lt; contents.length; i++) {
                append_contents(contents[i][0], contents[i][1]);
            }
            if (order != null) {
                var new_cells = {};
                body.innerHTML = &quot;&quot