title: What is the maximum size for the postMessage method that enables inter-frame communication?
body: <p>It's not clear from searching on Google and looking through documentation. What's the maximum length on a message sent via <code>Window.postMessage</code> (<a href="https://developer.mozilla.org/en-US/docs/Web/API/Window.postMessage" rel="noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/Window.postMessage</a>)? We assume this varies by browser?</p>