puppeteer/website/versioned_docs/version-19.4.0/api/puppeteer.coverage.md

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Coverage

Coverage class

The Coverage class provides methods to gathers information about parts of JavaScript and CSS that were used by the page.

Signature:

export declare class Coverage

Remarks

To output coverage in a form consumable by Istanbul, see puppeteer-to-istanbul.

Example

An example of using JavaScript and CSS coverage to get percentage of initially executed code:

// Enable both JavaScript and CSS coverage
await Promise.all([
  page.coverage.startJSCoverage(),
  page.coverage.startCSSCoverage(),
]);
// Navigate to page
await page.goto('https://example.com');
// Disable both JavaScript and CSS coverage
const [jsCoverage, cssCoverage] = await Promise.all([
  page.coverage.stopJSCoverage(),
  page.coverage.stopCSSCoverage(),
]);
let totalBytes = 0;
let usedBytes = 0;
const coverage = [...jsCoverage, ...cssCoverage];
for (const entry of coverage) {
  totalBytes += entry.text.length;
  for (const range of entry.ranges) usedBytes += range.end - range.start - 1;
}
console.log(`Bytes used: ${(usedBytes / totalBytes) * 100}%`);

Constructors

Constructor	Modifiers	Description
(constructor)(client)		Constructs a new instance of the Coverage class

Methods

Method	Modifiers	Description
startCSSCoverage(options)
startJSCoverage(options)
stopCSSCoverage()
stopJSCoverage()