[Question] Does playwright support browser network emulation?

[devalevenkatesh]

I guess Puppeteer supports network emulation / throttling. I am looking for something similar using Playwright. I checked the API reference but did not found anything in Network section. Thanks for such a great library.

[aslushnikov]

@devalevenkatesh Puppeteer's network throttling is done using Chrome DevTool Protocol; you can do the same with chromium in Playwright using context.newCDPSession():

const {chromium} = require('playwright');

(async () => {
  const browser = await chromium.launch();
  const context = await browser.newContext();
  const page = await context.newPage();
  const cdp = await context.newCDPSession(page);
  // Set throttling property
  await cdp.send('Network.emulateNetworkConditions', {
    'offline': false,
    'downloadThroughput': 200 * 1024 / 8,
    'uploadThroughput': 200 * 1024 / 8,
    'latency': 20
  });
  // Go on with the throttled page...
  await page.goto('https://example.com');
})();

This method, however, has a few downsides:

• will not work in other browsers in Playwright since there's no CDP
• does not work ideally in Chromium either since webrtc and websockets are not throttled

To throttle "for real", we'd recommend user-land solutions:

• Charles Proxy is quite popular and works across OS'es.
• On Linux, network shaping could be configured per network interface with tools like tc. wondershaper is a convenience wrapper atop of tc and might be a good starting point.
• On Mac, there's Network Link Conditioner.

Hope this helps!