JSFiddle - React, Tailwind, and code Playground

HTML

<button>Set JSON</button>

JavaScript

var chatroom = {
    json: null,
    render: function () {
        alert( 'render() invoked...' );
    }
};

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

document.getElementsByTagName( 'button' )[0].onclick = function () {
    chatroom.json = '{}';
};