differences from playwright

Differences from Playwright

invisible-playwright adds nothing to Playwright's API: every method, option and argument is Playwright's own. Where it cannot do what Playwright does without leaving something a page can see, or without claiming to have done something it did not, it says so with an error instead of pretending. This page lists those places.

Objects that are not implemented

These exist only so the object tree is well formed. Every call on them raises an error that names the reason.

Object	Why
Tracing	It records a session for the trace viewer and drives none of it. tracing.stop() is accepted and does nothing, so code that always stops a trace keeps working.
APIRequestContext (context.request, playwright.request)	It sends HTTP from outside the page, without the browser's fingerprint, which is the opposite of what this package is for.

Calls that are refused

Call	What happens	Why
set_input_files() with a folder	Error	The engine takes files. Pass the files inside the folder.
set_input_files() with an in-memory payload	Works, but mimeType is ignored	The payload is written to a file and handed over the way a user's pick is, so Firefox derives the type from the file name, as it does for a real pick.
drop() with an explicit data payload	Error	The engine builds the DataTransfer from a real pointer drag. Use drag_and_drop().
route_web_socket()	Error	The engine reports WebSocket frames but cannot hold or rewrite one, so a route would look like it worked and pass everything through.
Screencast to a video file	Error	The engine streams JPEG frames and has no encoder. Pass on_frame= to receive the frames.
register_selector_engine() or set_test_id_attribute() after a page exists	Error	Both are built into the page's injected script when it is created. Call them before the first page.
expose_binding(), expose_function()	Error, not implemented yet	The page-facing half is easy; the reply path into the page's promise is not wired, and a binding that never answers would hang the page.
set_storage_state() with per-origin localStorage	Error, not implemented yet	Restoring only the cookies would look like success and leave half the session missing.
response.body() on a very large or old response	Error	The engine keeps at most 100 MB of response bodies per tab and 10 MB per response. Read the body sooner.

Behaviour that differs on purpose

• service_workers="block" is honoured by the engine itself, per context, with no page script: register() fails the way it fails when the worker's script is unreachable, and navigator.serviceWorker stays native. Playwright does it with a page script whose source names Playwright. On a persistent profile, turning the block on removes the service workers the profile had saved for that context, and they do not come back when the block is turned off.
• Language. locale="auto" (the default) declares the language of a Firefox build people in the proxy's country actually run. An explicit locale is navigator.language, followed by the fallbacks Firefox itself adds (en-AU, en-US, en).
• Human input. With humanize=True (the default) the pointer moves along a paced path, typing pauses before the first key, and a file chooser waits as a person looking for the file does. Calls take longer than in Playwright, and the page sees a person's timing.
• The server speaks to this client only. The bundled Playwright client and the bundled server are versioned together; a stock Playwright client cannot drive the server directly.