act as proxy/intercept

[sdg9]

For our initial use case fetch is likely the best place to start.

Idea is with a line of code or two clients using the fetch API actually have their requests processed directly by mezzo to persist to disc for future replay.

Code out there to get familiar with

• https://github.com/Netflix/pollyjs/tree/master/packages/%40pollyjs/adapter-fetch
  • Inspired by https://github.com/pretenderjs/pretender, pretender mocks out XHR and fetch, but fetch uses https://github.com/github/fetch so only supports browser polyfill (not node)
  • May be more than we need as it can seamlessly replay as well. The recording concept would be ideal/step 1.
  • Why do they use custom eventEmitter over https://nodejs.dev/learn/the-nodejs-event-emitter?
• https://httptoolkit.tech/blog/javascript-mitm-proxy-mockttp/ which is a passthrough proxy built in TS but freemium
  • https://github.com/httptoolkit/mockttp
• https://github.com/mlegenhausen/fetch-intercept lets you "intercept" fetch
  • With minimal code we can monitor all responses. It's possible this is close/sufficient for recording purposes.

Possible alternative implementation are acting as a layer 7/TLS terminating proxy or supporting XHR.

Poly has a nice configurable implementation, for example we could create a new "adapter" package for a fetch interceptor and a new "persister" package for fs storage and let the user customize it as desired.

[sdg9]

How reactotron does it https://github.com/infinitered/reactotron-react-native/blob/master/src/plugins/networking.ts

Per this comment

In react-native fetch is being polyfilled by whatwg-fetch and uses XMLHttpRequest internally. On the web, you are right; it is a different implementation.

[sdg9]

Moving recording to separate issue