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---
id: class-chromiumcoverage
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title: "ChromiumCoverage"
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---
Coverage gathers information about parts of JavaScript and CSS that were used by the page.
An example of using JavaScript coverage to produce Istambul report for page load:
```js
const { chromium } = require('playwright');
const v8toIstanbul = require('v8-to-istanbul');
(async() => {
const browser = await chromium.launch();
const page = await browser.newPage();
await page.coverage.startJSCoverage();
await page.goto('https://chromium.org');
const coverage = await page.coverage.stopJSCoverage();
for (const entry of coverage) {
const converter = new v8toIstanbul('', 0, { source: entry.source });
await converter.load();
converter.applyCoverage(entry.functions);
console.log(JSON.stringify(converter.toIstanbul()));
}
await browser.close();
})();
```
- [chromiumCoverage.startCSSCoverage([options])](api/class-chromiumcoverage.md#chromiumcoveragestartcsscoverageoptions )
- [chromiumCoverage.startJSCoverage([options])](api/class-chromiumcoverage.md#chromiumcoveragestartjscoverageoptions )
- [chromiumCoverage.stopCSSCoverage() ](api/class-chromiumcoverage.md#chromiumcoveragestopcsscoverage )
- [chromiumCoverage.stopJSCoverage() ](api/class-chromiumcoverage.md#chromiumcoveragestopjscoverage )
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## chromiumCoverage.startCSSCoverage([options])
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- `options` < [Object]>
- `resetOnNavigation` < [boolean]> Whether to reset coverage on every navigation. Defaults to `true` .
- returns: < [Promise]>
Returns coverage is started
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## chromiumCoverage.startJSCoverage([options])
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- `options` < [Object]>
- `reportAnonymousScripts` < [boolean]> Whether anonymous scripts generated by the page should be reported. Defaults to `false` .
- `resetOnNavigation` < [boolean]> Whether to reset coverage on every navigation. Defaults to `true` .
- returns: < [Promise]>
Returns coverage is started
> **NOTE** Anonymous scripts are ones that don't have an associated url. These are scripts that are dynamically created on the page using `eval` or `new Function`. If `reportAnonymousScripts` is set to `true`, anonymous scripts will have `__playwright_evaluation_script__` as their URL.
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## chromiumCoverage.stopCSSCoverage()
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- returns: < [Promise]< [Array]< [Object]>>>
- `url` < [string]> StyleSheet URL
- `text` < [string]> StyleSheet content, if available.
- `ranges` < [Array]< [Object]>> StyleSheet ranges that were used. Ranges are sorted and non-overlapping.
- `start` < [number]> A start offset in text, inclusive
- `end` < [number]> An end offset in text, exclusive
Returns the array of coverage reports for all stylesheets
> **NOTE** CSS Coverage doesn't include dynamically injected style tags without sourceURLs.
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## chromiumCoverage.stopJSCoverage()
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- returns: < [Promise]< [Array]< [Object]>>>
- `url` < [string]> Script URL
- `scriptId` < [string]> Script ID
- `source` < [string]> Script content, if applicable.
- `functions` < [Array]< [Object]>> V8-specific coverage format.
- `functionName` < [string]>
- `isBlockCoverage` < [boolean]>
- `ranges` < [Array]< [Object]>>
- `count` < [number]>
- `startOffset` < [number]>
- `endOffset` < [number]>
Returns the array of coverage reports for all scripts
> **NOTE** JavaScript Coverage doesn't include anonymous scripts by default. However, scripts with sourceURLs are reported.
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[Playwright]: api/class-playwright.md "Playwright"
[Browser]: api/class-browser.md "Browser"
[BrowserContext]: api/class-browsercontext.md "BrowserContext"
[Page]: api/class-page.md "Page"
[Frame]: api/class-frame.md "Frame"
[ElementHandle]: api/class-elementhandle.md "ElementHandle"
[JSHandle]: api/class-jshandle.md "JSHandle"
[ConsoleMessage]: api/class-consolemessage.md "ConsoleMessage"
[Dialog]: api/class-dialog.md "Dialog"
[Download]: api/class-download.md "Download"
[Video]: api/class-video.md "Video"
[FileChooser]: api/class-filechooser.md "FileChooser"
[Keyboard]: api/class-keyboard.md "Keyboard"
[Mouse]: api/class-mouse.md "Mouse"
[Touchscreen]: api/class-touchscreen.md "Touchscreen"
[Request]: api/class-request.md "Request"
[Response]: api/class-response.md "Response"
[Selectors]: api/class-selectors.md "Selectors"
[Route]: api/class-route.md "Route"
[WebSocket]: api/class-websocket.md "WebSocket"
[TimeoutError]: api/class-timeouterror.md "TimeoutError"
[Accessibility]: api/class-accessibility.md "Accessibility"
[Worker]: api/class-worker.md "Worker"
[BrowserServer]: api/class-browserserver.md "BrowserServer"
[BrowserType]: api/class-browsertype.md "BrowserType"
[Logger]: api/class-logger.md "Logger"
[ChromiumBrowser]: api/class-chromiumbrowser.md "ChromiumBrowser"
[ChromiumBrowserContext]: api/class-chromiumbrowsercontext.md "ChromiumBrowserContext"
[ChromiumCoverage]: api/class-chromiumcoverage.md "ChromiumCoverage"
[CDPSession]: api/class-cdpsession.md "CDPSession"
[FirefoxBrowser]: api/class-firefoxbrowser.md "FirefoxBrowser"
[WebKitBrowser]: api/class-webkitbrowser.md "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"
[Evaluation Argument]: ./core-concepts.md#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"