📄 playwright-python/python/docs/api/class-websocket

File: class-websocket.md | Updated: 11/18/2025

Source: https://playwright.dev/python/docs/api/class-websocket

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The WebSocket class represents WebSocket connections within a page. It provides the ability to inspect and manipulate the data being transmitted and received.

If you want to intercept or modify WebSocket frames, consider using WebSocketRoute .

Methods​

expect_event​

Added before v1.9 webSocket.expect_event

Waits for event to fire and passes its value into the predicate function. Returns when the predicate returns truthy value. Will throw an error if the webSocket is closed before the event is fired. Returns the event data value.

Usage

web_socket.expect_event(event)web_socket.expect_event(event, **kwargs)

Arguments

  • event str #

    Event name, same one would pass into webSocket.on(event).

  • predicate Callable (optional)#

    Receives the event data and resolves to truthy value when the waiting should resolve.

  • timeout float (optional)#

    Maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the browser_context.set_default_timeout() .

Returns

wait_for_event​

Added before v1.9 webSocket.wait_for_event

note

In most cases, you should use web_socket.expect_event() .

Waits for given event to fire. If predicate is provided, it passes event's value into the predicate function and waits for predicate(event) to return a truthy value. Will throw an error if the socket is closed before the event is fired.

Usage

web_socket.wait_for_event(event)web_socket.wait_for_event(event, **kwargs)

Arguments

  • event str #

    Event name, same one typically passed into *.on(event).

  • predicate Callable (optional)#

    Receives the event data and resolves to truthy value when the waiting should resolve.

  • timeout float (optional)#

    Maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the browser_context.set_default_timeout() .

Returns

Properties​

is_closed​

Added before v1.9 webSocket.is_closed

Indicates that the web socket has been closed.

Usage

web_socket.is_closed()

Returns

url​

Added before v1.9 webSocket.url

Contains the URL of the WebSocket.

Usage

web_socket.url

Returns

Events​

on("close")[​](https://playwright.dev/python/docs/api/class-websocket#web-socket-event-close "Direct link to on("close")")

Added before v1.9 webSocket.on("close")

Fired when the websocket closes.

Usage

web_socket.on("close", handler)

Event data

on("framereceived")[​](https://playwright.dev/python/docs/api/class-websocket#web-socket-event-frame-received "Direct link to on("framereceived")")

Added in: v1.9 webSocket.on("framereceived")

Fired when the websocket receives a frame.

Usage

web_socket.on("framereceived", handler)

Event data

on("framesent")[​](https://playwright.dev/python/docs/api/class-websocket#web-socket-event-frame-sent "Direct link to on("framesent")")

Added in: v1.9 webSocket.on("framesent")

Fired when the websocket sends a frame.

Usage

web_socket.on("framesent", handler)

Event data

on("socketerror")[​](https://playwright.dev/python/docs/api/class-websocket#web-socket-event-socket-error "Direct link to on("socketerror")")

Added in: v1.9 webSocket.on("socketerror")

Fired when the websocket has an error.

Usage

web_socket.on("socketerror", handler)

Event data