The main difference between the two pages is the method of sending messages. Recieving messages is the same in both.
Send messages to iframe using iframeEl.contentWindow.postMessage
Recieve messages using window.addEventListener('message')
First, go to https://<yourname>.sanity.studio
(or to the url of your studio if it's hosted elsewhere). Then open the developer console (usually by one of the keyboard shortcuts Command+Option+I
, F12
or Control+Shift+I
depending on what browser/platform you are using)
app.bundle.js
file in the sidebar tree view.