[Feature] Target interception

[szmarczak]

Previous issue: #1101
Related: #13111

There is context.addInitScript, however it doesn't solve all cases where target interception is needed.
For example, if there are CDP messages to be sent. I'm using CDP for response interception, which cannot be done via Playwright yet.

In my opinion, there should be a way to intercept target creation, so Node.js code can be executed (and that enables a wide array of other possibilities) before webpage scripts are ran.

[rwoll]

I'm using CDP for response interception, which cannot be done via Playwright yet.

If your use case is response interception/modification, does https://playwright.dev/docs/network#modify-responses work for you?

[szmarczak]

Unfortunately it doesn't, as it uses Node.js HTTP API under the hood - this disables HTTP/2 - the behavior isn't the same.

Fetch.continueResponse works for me. Ideally I'd like to capture all new targets, send some CDP messages, then resume target's work.

[yury-s]

Unfortunately it doesn't, as it uses Node.js HTTP API under the hood - this disables HTTP/2 - the behavior isn't the same.

Can you tell us more about your use case and where it fails with the current implementation but works with Fetch.continueResponse?

Fetch.continueResponse works for me.

We added that method during the first iteration on this feature but then moved away from it due to some technical issues. What we could do currently is to (optionally) use http2 instead of https but I'm not sure if that would address your problem given the requirements you mentioned above, we need to better understand your scenario.

[szmarczak]

Can you tell us more about your use case and where it fails with the current implementation but works with Fetch.continueResponse?

Automation. Some websites reject requests if the fingerprint doesn't match real browsers.

I'm not sure if that would address your problem

We've developed an npm package that tries to mimic the browser behavior, so we could use that instead. However that's not the best solution.

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Target interception would also enable adding init scripts dynamically - this is not limited to response interception. E.g. different pages would have slightly different scripts.

[szmarczak]

FYI target interception is currently blocked by https://crbug.com/1070568

[pavelfeldman]

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