playwright/docs/troubleshooting.md

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# Troubleshooting

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- [Browser dependencies](#browser-dependencies)
- [Code transpilation issues](#code-transpilation-issues)
- [Node.js requirements](#nodejs-requirements)
  * [ReferenceError: URL is not defined](#referenceerror-url-is-not-defined)
<!-- GEN:stop -->

## Browser dependencies

Playwright does self-inspection every time it runs to make sure the browsers can
be launched successfully. If there are missing dependencies, playwright will
print instructions to acquire them.

We also provide [Ubuntu 18.04 dockerfile](docker/Dockerfile.bionic) and
[Ubuntu 20.04 dockerfile](docker/Dockerfile.focal) with the list of Debian
dependencies.

## Code transpilation issues

If you are using a JavaScript transpiler like babel or TypeScript, calling
`evaluate()` with an async function might not work. This is because while
`playwright` uses `Function.prototype.toString()` to serialize functions while
transpilers could be changing the output code in such a way it's incompatible
with `playwright`.

Some workarounds to this problem would be to instruct the transpiler not to mess
up with the code, for example, configure TypeScript to use latest ECMAScript
version (`"target": "es2018"`). Another workaround could be using string
templates instead of functions:

```js
await page.evaluate(`(async() => {
   console.log('1');
})()`);
```

## Node.js requirements

### ReferenceError: URL is not defined

Playwright requires Node.js 10 or higher. Node.js 8 is not supported, and will
cause you to receive this error.

# Please file an issue

Playwright is a new project, and we are watching the issues very closely. As we
solve common issues, this document will grow to include the common answers.
[Playwright]: api.md#class-playwright "Playwright"
[Browser]: api.md#class-browser "Browser"
[BrowserContext]: api.md#class-browsercontext "BrowserContext"
[Page]: api.md#class-page "Page"
[Frame]: api.md#class-frame "Frame"
[ElementHandle]: api.md#class-elementhandle "ElementHandle"
[JSHandle]: api.md#class-jshandle "JSHandle"
[ConsoleMessage]: api.md#class-consolemessage "ConsoleMessage"
[Dialog]: api.md#class-dialog "Dialog"
[Download]: api.md#class-download "Download"
[Video]: api.md#class-video "Video"
[FileChooser]: api.md#class-filechooser "FileChooser"
[Keyboard]: api.md#class-keyboard "Keyboard"
[Mouse]: api.md#class-mouse "Mouse"
[Touchscreen]: api.md#class-touchscreen "Touchscreen"
[Request]: api.md#class-request "Request"
[Response]: api.md#class-response "Response"
[Selectors]: api.md#class-selectors "Selectors"
[Route]: api.md#class-route "Route"
[WebSocket]: api.md#class-websocket "WebSocket"
[TimeoutError]: api.md#class-timeouterror "TimeoutError"
[Accessibility]: api.md#class-accessibility "Accessibility"
[Worker]: api.md#class-worker "Worker"
[BrowserServer]: api.md#class-browserserver "BrowserServer"
[BrowserType]: api.md#class-browsertype "BrowserType"
[Logger]: api.md#class-logger "Logger"
[ChromiumBrowser]: api.md#class-chromiumbrowser "ChromiumBrowser"
[ChromiumBrowserContext]: api.md#class-chromiumbrowsercontext "ChromiumBrowserContext"
[ChromiumCoverage]: api.md#class-chromiumcoverage "ChromiumCoverage"
[CDPSession]: api.md#class-cdpsession "CDPSession"
[FirefoxBrowser]: api.md#class-firefoxbrowser "FirefoxBrowser"
[WebKitBrowser]: api.md#class-webkitbrowser "WebKitBrowser"
[Array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array "Array"
[Buffer]: https://nodejs.org/api/buffer.html#buffer_class_buffer "Buffer"
[ChildProcess]: https://nodejs.org/api/child_process.html "ChildProcess"
[Element]: https://developer.mozilla.org/en-US/docs/Web/API/element "Element"
[Error]: https://nodejs.org/api/errors.html#errors_class_error "Error"
[EvaluationArgument]: #evaluationargument "Evaluation Argument"
[Map]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map "Map"
[Object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object "Object"
[Promise]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise"
[RegExp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp "RegExp"
[Serializable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Description "Serializable"
[UIEvent.detail]: https://developer.mozilla.org/en-US/docs/Web/API/UIEvent/detail "UIEvent.detail"
[URL]: https://nodejs.org/api/url.html "URL"
[USKeyboardLayout]: ../src/usKeyboardLayout.ts "USKeyboardLayout"
[UnixTime]: https://en.wikipedia.org/wiki/Unix_time "Unix Time"
[boolean]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type "Boolean"
[function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function "Function"
[iterator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols "Iterator"
[null]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/null "null"
[number]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type "Number"
[origin]: https://developer.mozilla.org/en-US/docs/Glossary/Origin "Origin"
[selector]: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors "selector"
[Readable]: https://nodejs.org/api/stream.html#stream_class_stream_readable "Readable"
[string]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type "string"
[xpath]: https://developer.mozilla.org/en-US/docs/Web/XPath "xpath"