Implementation:Microsoft Playwright Client CDPSession

Knowledge Sources	Microsoft_Playwright
Domains	Browser Automation, Chrome DevTools Protocol
Last Updated	2026-02-12 00:00 GMT

Overview

Concrete tool for interacting with browser targets via the Chrome DevTools Protocol (CDP) provided by the Playwright library.

Description

The CDPSession class extends ChannelOwner and implements the api.CDPSession interface. It provides a client-side wrapper for sending CDP commands and receiving CDP events from Chromium-based browsers. The constructor wires up the channel's 'event' emissions to re-emit them on the CDPSession instance, and explicitly binds event listener methods (on, addListener, off, removeListener, once) from the parent class. The send() method accepts a typed CDP method name and parameters, dispatches the command through the channel, and returns the typed result. The detach() method disconnects the session from the target.

Usage

Use CDPSession when you need low-level access to the Chrome DevTools Protocol for Chromium browsers, such as intercepting network traffic at the protocol level, accessing performance metrics, or controlling features not exposed through Playwright's high-level API. Obtain a session via page.context().newCDPSession(page) or browser.newBrowserCDPSession().

Code Reference

Source Location

• Repository: Microsoft_Playwright
• File: packages/playwright-core/src/client/cdpSession.ts

Signature

export class CDPSession extends ChannelOwner<channels.CDPSessionChannel> implements api.CDPSession {
  static from(cdpSession: channels.CDPSessionChannel): CDPSession;

  constructor(parent: ChannelOwner, type: string, guid: string, initializer: channels.CDPSessionInitializer);

  async send<T extends keyof Protocol.CommandParameters>(
    method: T,
    params?: Protocol.CommandParameters[T]
  ): Promise<Protocol.CommandReturnValues[T]>;

  async detach(): Promise<void>;
}

Import

import { CDPSession } from 'playwright-core/src/client/cdpSession';

I/O Contract

Inputs

Name	Type	Required	Description
method	keyof Protocol.CommandParameters	Yes	The CDP method name to invoke (e.g., 'Network.enable')
params	Protocol.CommandParameters[T]	No	The parameters for the CDP command

Outputs

Name	Type	Description
send()	Promise<Protocol.CommandReturnValues[T]>	The typed result of the CDP command
detach()	Promise<void>	Detaches the CDP session from its target

Usage Examples

const client = await page.context().newCDPSession(page);

// Enable network domain
await client.send('Network.enable');

// Listen for CDP events
client.on('Network.requestWillBeSent', (params) => {
  console.log('Request:', params.request.url);
});

// Send a CDP command with parameters
const result = await client.send('Runtime.evaluate', {
  expression: 'document.title',
});
console.log('Title:', result.result.value);

// Detach session
await client.detach();

Related Pages

• Environment:Microsoft_Playwright_Node_Runtime_Environment