mirror of
https://github.com/puppeteer/puppeteer
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185 lines
7.7 KiB
Markdown
185 lines
7.7 KiB
Markdown
# FAQ
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## Q: Who maintains Puppeteer?
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The Chrome Browser Automation team maintains the library, but we'd love your help and
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expertise on the project! See our
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[contributing guide](https://pptr.dev/contributing).
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## Q: What is the status of cross-browser support?
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Official Firefox support is currently experimental. The ongoing collaboration
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with Mozilla aims to support common end-to-end testing use cases, for which
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developers expect cross-browser coverage. The Puppeteer team needs input from
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users to stabilize Firefox support and to bring missing APIs to our attention.
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From Puppeteer v2.1.0 onwards you can specify
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[`puppeteer.launch({product: 'firefox'})`](./api/puppeteer.puppeteernode.launch)
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to run your Puppeteer scripts in Firefox Nightly, without any additional custom
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patches. While
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[an older experiment](https://www.npmjs.com/package/puppeteer-firefox) required
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a patched version of Firefox,
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[the current approach](https://wiki.mozilla.org/Remote) works with “stock”
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Firefox.
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We will continue to collaborate with other browser vendors to bring Puppeteer
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support to browsers such as Safari. This effort includes exploration of a
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standard for executing cross-browser commands (instead of relying on the
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non-standard DevTools Protocol used by Chrome).
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## Q: What are Puppeteer’s goals and principles?
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The goals of the project are:
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- Provide a reference implementation that highlights the capabilities of the
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[Chrome DevTools](https://chromedevtools.github.io/devtools-protocol/)
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and [WebDriver BiDi](https://w3c.github.io/webdriver-bidi/) protocols.
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- Grow the adoption of automated cross-browser testing.
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- Help dogfood new DevTools Protocol and WebDriver BiDi features...and catch bugs!
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- Learn more about the pain points of automated browser testing and help fill
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those gaps.
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We adapt
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[Chromium principles](https://www.chromium.org/developers/core-principles) to
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help us drive product decisions:
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- **Speed**: Puppeteer has almost zero performance overhead over an automated
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page.
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- **Security**: Puppeteer operates off-process with respect to the browser, making
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it safe to automate potentially malicious pages.
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- **Stability**: Puppeteer should not be flaky and should not leak memory.
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- **Simplicity**: Puppeteer provides a high-level API that’s easy to use,
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understand, and debug.
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## Q: Is Puppeteer a replacement for Selenium WebDriver?
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**No**. Both projects are valuable for very different reasons:
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- Selenium WebDriver focuses on cross-browser automation and provides bindings for
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multiple languages; Puppeteer is only for JavaScript.
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- Puppeteer focuses on Chromium; its value proposition is richer functionality
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for Chromium-based browsers.
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That said, you **can** use Puppeteer to run tests against Chromium, e.g. using
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the community-driven
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[jest-puppeteer](https://github.com/smooth-code/jest-puppeteer) or
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[Puppeteer's Angular integration](https://pptr.dev/integrations/ng-schematics). While this
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probably shouldn’t be your only testing solution, it does have a few good points
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compared to WebDriver classic:
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- Puppeteer requires zero setup and comes bundled with the Chrome version it
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works best with, making it
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[very easy to start with](https://github.com/puppeteer/puppeteer/#getting-started).
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- Puppeteer has event-driven architecture, which removes a lot of potential
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flakiness. There’s no need for “sleep(1000)” calls in puppeteer scripts.
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- Puppeteer exposes browser contexts, making it possible to efficiently
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parallelize test execution.
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- Puppeteer shines when it comes to debugging: flip the “headless” bit to false,
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add “slowMo”, and you’ll see what the browser is doing. You can even open
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Chrome DevTools to inspect the test environment.
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## Q: Why doesn’t Puppeteer v.XXX work with Chromium v.YYY?
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We see Puppeteer as an **indivisible entity** with Chromium. Each version of
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Puppeteer bundles a specific version of Chromium – **the only** version it is
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guaranteed to work with.
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This is not an artificial constraint: A lot of work on Puppeteer is actually
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taking place in the Chromium repository. Here’s a typical story:
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- A Puppeteer bug is reported:
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https://github.com/puppeteer/puppeteer/issues/2709
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- It turned out this is an issue with the DevTools protocol, so we’re fixing it
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in Chromium: https://chromium-review.googlesource.com/c/chromium/src/+/1102154
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- Once the upstream fix is landed, we roll updated Chromium into Puppeteer:
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https://github.com/puppeteer/puppeteer/pull/2769
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## Q: Which Chrome version does Puppeteer use?
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Look for the `chrome` entry in
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[revisions.ts](https://github.com/puppeteer/puppeteer/blob/main/packages/puppeteer-core/src/revisions.ts).
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## Q: Which Firefox version does Puppeteer use?
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Since Firefox support is experimental, Puppeteer downloads the latest
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[Firefox Nightly](https://wiki.mozilla.org/Nightly) when the `PUPPETEER_PRODUCT`
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environment variable is set to `firefox`. That's also why the value of `firefox`
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in
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[revisions.ts](https://github.com/puppeteer/puppeteer/blob/main/packages/puppeteer-core/src/revisions.ts)
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is `latest` -- Puppeteer isn't tied to a particular Firefox version.
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To fetch Firefox Nightly as part of Puppeteer installation:
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```bash
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PUPPETEER_PRODUCT=firefox npm i puppeteer
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```
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To download Firefox Nightly into an existing Puppeteer project:
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```bash
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npx puppeteer browsers install firefox
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```
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## Q: What’s considered a “Navigation”?
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From Puppeteer’s standpoint, **“navigation” is anything that changes a page’s
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URL**. Aside from regular navigation where the browser hits the network to fetch
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a new document from the web server, this includes
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[anchor navigations](https://www.w3.org/TR/html5/single-page.html#scroll-to-fragid)
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and [History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API)
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usage.
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With this definition of “navigation,” **Puppeteer works seamlessly with
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single-page applications.**
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## Q: What’s the difference between a “trusted" and "untrusted" input event?
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In browsers, input events could be divided into two big groups: trusted vs.
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untrusted.
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- **Trusted events**: events generated by users interacting with the page, e.g.
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using a mouse or keyboard.
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- **Untrusted event**: events generated by Web APIs, e.g. `document.createEvent`
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or `element.click()` methods.
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Websites can distinguish between these two groups:
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- using an
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[`Event.isTrusted`](https://developer.mozilla.org/en-US/docs/Web/API/Event/isTrusted)
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event flag
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- sniffing for accompanying events. For example, every trusted `'click'` event
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is preceded by `'mousedown'` and `'mouseup'` events.
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For automation purposes it’s important to generate trusted events. **All input
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events generated with Puppeteer are trusted and fire proper accompanying
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events.** If, for some reason, one needs an untrusted event, it’s always
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possible to hop into a page context with `page.evaluate` and generate a fake
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event:
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```ts
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await page.evaluate(() => {
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document.querySelector('button[type=submit]').click();
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});
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```
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## Q: Does Puppeteer support media and audio playback?
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Puppeteer uses [Chrome for Testing](https://developer.chrome.com/blog/chrome-for-testing/) binaries
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by default which ship with properietary codecs support starting from
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[M120](https://chromiumdash.appspot.com/commit/12d607016c31ea13579e897740c765be189ed6eb).
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## Q: I am having trouble installing / running Puppeteer in my test environment. Where should I look for help?
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We have a
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[troubleshooting](https://pptr.dev/troubleshooting)
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guide for various operating systems that lists the required dependencies.
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## Q: I have more questions! Where do I ask?
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There are many ways to get help on Puppeteer:
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- For questions: [Stack Overflow](https://stackoverflow.com/questions/tagged/puppeteer)
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- For bug reports: [GitHub Issues](https://github.com/puppeteer/puppeteer/issues)
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Make sure to search these channels before posting your question.
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