I have a class, ChatRoom, that can only render after it receives a long-running HTTP request (it could take 1 second or 30 seconds). So I need to delay rendering until ChatRoom.json is not null.

In the code below, I'm using Closure Library's goog.async.ConditionalDelay. It works, but is there a better way (maybe without needing Closure Library) to do this?

ChatRoom.prototype.json = null; // received after a long-running HTTP request.



ChatRoom.prototype.render = function() {

    var thisChatRoom = this;



    function onReady() {

        console.log(Received JSON, thisChatRoom.json);

        // Do rendering...

    }



    function onFailure() {

        alert('Sorry, an error occurred. The chat room couldn't open');

    }



    function isReady() {

        if (thisChatRoom.json != null) {

            return true;

        }

        console.log(Waiting for chat room JSON...);

        return false;

    }



    // If there is a JSON request in progress, wait until it completes.

    if (isReady()) {

        onReady();

    } else {

        var delay = new goog.async.ConditionalDelay(isReady);

        delay.onSuccess = onReady;

        delay.onFailure = onFailure;

        delay.start(500, 5000);

    }

}

Note that while (json == null) { } isn't possible because that would be synchronous (blocking all other JS execution).