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')
Debounce a function when you want it to execute only once after a defined interval of time. If the event occurs multiple times within the interval, the interval is reset each time.
Example A user is typing into an input field and you want to execute a function, such as a call to the server, only when the user stops typing for a certain interval, such as 500ms.