Is it necessary to create a proxy.html file at the iframe's domain?

[nathanathan]

Is it necessary to create a proxy.html file at the iframe's domain? It seems like it should be possible to have the iframe itself act as the proxy. I understand why a proxy.html is needed on the parent frame's domain (you can't post cross domain up to a parent frame, so you post to a child frame with the parent's domain that relays the message), but the parent can post cross domain into its child frames.

[guatedude2]

I believe it's not necessary, as almost all of the newer browsers support window.postMessage, which is the transport layer that porthole uses. It's mostly for supporting legacy browsers. One of the things that porthole handles pretty well is the transfer argument, which is not supported by all browsers. Porthole converts the transport JSON object to string and then parses it back to JSON which is what makes this library great.

https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage#Browser_compatibility