Asynchronously delay JS until a condition is met

You could also achieve this using lodash's debouncer with recursion.

import _debounce from 'lodash/debounce';

const wait = (() => {
    if ( chatroom.json ) {
        chatroom.render();
    } else {
      _debounce(wait, 500)();
    }
})();

Consider this:

(function wait() {
    if ( chatroom.json ) {
        chatroom.render();
    } else {
        setTimeout( wait, 500 );
    }
})();

This will check every half second.

Live demo: http://jsfiddle.net/kBgTx/