<titledata-rh="true">Contributing | Puppeteer</title><metadata-rh="true"name="viewport"content="width=device-width,initial-scale=1"><metadata-rh="true"name="twitter:card"content="summary_large_image"><metadata-rh="true"property="og:url"content="https://pptr.dev/next/contributing"><metadata-rh="true"name="docusaurus_locale"content="en"><metadata-rh="true"name="docsearch:language"content="en"><metadata-rh="true"name="docusaurus_version"content="current"><metadata-rh="true"name="docusaurus_tag"content="docs-default-current"><metadata-rh="true"name="docsearch:version"content="current"><metadata-rh="true"name="docsearch:docusaurus_tag"content="docs-default-current"><metadata-rh="true"property="og:title"content="Contributing | Puppeteer"><metadata-rh="true"name="description"content="First of all, thank you for your interest in Puppeteer! We'd love to accept your"><metadata-rh="true"property="og:description"content="First of all, thank you for your interest in Puppeteer! We'd love to accept your"><linkdata-rh="true"rel="icon"href="/img/favicon.ico"><linkdata-rh="true"rel="canonical"href="https://pptr.dev/next/contributing"><linkdata-rh="true"rel="alternate"href="https://pptr.dev/next/contributing"hreflang="en"><linkdata-rh="true"rel="alternate"href="https://pptr.dev/next/contributing"hreflang="x-default"><linkrel="stylesheet"href="/assets/css/styles.acc20982.css">
patches and contributions!</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="contributor-license-agreement">Contributor License Agreement<aclass="hash-link"href="#contributor-license-agreement"title="Direct link to heading"></a></h2><p>Contributions to this project must be accompanied by a Contributor License
Agreement. You (or your employer) retain the copyright to your contribution,
this simply gives us permission to use and redistribute your contributions as
part of the project. Head over to <ahref="https://cla.developers.google.com/"target="_blank"rel="noopener noreferrer">https://cla.developers.google.com/</a> to see
your current agreements on file or to sign a new one.</p><p>You generally only need to submit a CLA once, so if you've already submitted one
(even if it was for a different project), you probably don't need to do it
Chromium version installed locally (you only need to do this once, not on
every test run) and then you can run the tests:</p><divclass="language-bash codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token assign-left variable"style="color:#36acaa">PUPPETEER_EXPERIMENTAL_CHROMIUM_MAC_ARM</span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token number"style="color:#36acaa">1</span><spanclass="token plain"></span><spanclass="token function"style="color:#d73a49">npm</span><spanclass="token plain"></span><spanclass="token function"style="color:#d73a49">install</span><spanclass="token plain"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"></span><spanclass="token assign-left variable"style="color:#36acaa">PUPPETEER_EXPERIMENTAL_CHROMIUM_MAC_ARM</span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token number"style="color:#36acaa">1</span><spanclass="token plain"></span><spanclass="token function"style="color:#d73a49">npm</span><spanclass="token plain"> run </span><spanclass="token builtin class-name">test</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></li><li><p>To run tests with custom browser executable:</p><divclass="language-bash codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token assign-left variable"style="color:#36acaa">BINARY</span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token operator"style="color:#393A34"><</span><spanclass="token plain">path-to-chrome/firefox-executable</span><spanclass="token operator"style="color:#393A34">></span><spanclass="token plain"></span><spanclass="token function"style="color:#d73a49">npm</span><spanclass="token plain"> run test:chrome </span><spanclass="token comment"style="color:#999988;font-style:italic"># Or npm run test:firefox</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></li></ul><h2class="anchor anchorWithStickyNavbar_LWe7"id="building-a-single-package">Building a single package<aclass="hash-link"href="#building-a-single-package"title="Direct link to heading"></a></h2><p>To build a single package, you can run</p><divclass="language-sh codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token plain">npm run build --workspace <package> # e.g. puppeteer</spa
packages is sufficient. This is all possible due to
<ahref="https://github.com/google/wireit"target="_blank"rel="noopener noreferrer">wireit</a> which behaves similar to
<ahref="https://www.gnu.org/software/make/"target="_blank"rel="noopener noreferrer">GNU Make</a>.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="removing-stale-artifacts">Removing stale artifacts<aclass="hash-link"href="#removing-stale-artifacts"title="Direct link to heading"></a></h2><p>It's possible some generated artifacts (such as
<code>packages/puppeteer-core/src/types.ts</code>) can become stale since these artifacts
rely on complex conditions (such as names of distinct files) that cannot be
captured by the build system. To clean artifacts, you can run</p><divclass="language-sh codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token plain">npm run clean # or npm run clean --workspace <package></span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2class="anchor anchorWithStickyNavbar_LWe7"id="comprehensive-testing">Comprehensive testing<aclass="hash-link"href="#comprehensive-testing"title="Direct link to heading"></a></h2><p>Outside of <code>npm test</code>, there are several other
<ahref="https://docs.npmjs.com/cli/v8/using-npm/scripts"target="_blank"rel="noopener noreferrer"><code>npm</code> scripts</a> that are
usually check through CI:</p><ul><li><code>test-install</code> - Tests whether <code>puppeteer</code> and <code>puppeteer-core</code> install
properly and are functional.</li><li><code>test-types</code> - Tests the TypeScript types in <code>puppeteer</code> using
<ahref="https://github.com/SamVerschueren/tsd"target="_blank"rel="noopener noreferrer"><code>tsd</code></a>.</li><li><code>test:chrome:**</code> - Tests <code>puppeteer</code> on Chromium.</li><li><code>test:firefox:**</code> - Tests <code>puppeteer</code> on Firefox.</li></ul><p>The default <code>npm test</code> runs <code>test:{chrome,firefox}:headless</code> which is generally
sufficient.</p><p>Puppeteer uses a custom test runner on top of Mocha that consults the
to see if a given test result is expected or not. See more info about the test
runner in
<ahref="https://github.com/puppeteer/puppeteer/tree/main/tools/mochaRunner"target="_blank"rel="noopener noreferrer"><code>tools/mochaRunner</code></a>.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="code-reviews">Code reviews<aclass="hash-link"href="#code-reviews"title="Direct link to heading"></a></h2><p>All submissions, including submissions by project members, require review. We
use GitHub pull requests for this purpose. Consult
<ahref="https://help.github.com/articles/about-pull-requests/"target="_blank"rel="noopener noreferrer">GitHub Help</a> for more
information on using pull requests.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="code-style">Code Style<aclass="hash-link"href="#code-style"title="Direct link to heading"></a></h2><p>Our coding style is fully defined in
manually by running:</p><divclass="language-bash codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token function"style="color:#d73a49">npm</span><spanclass="token plain"> run lint</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>If some errors are returned, you can attempt to fix them using:</p><divclass="language-bash codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token function"style="color:#d73a49">npm</span><spanclass="token plain"> run </span><spanclass="token function"style="color:#d73a49">format</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2class="anchor anchorWithStickyNavbar_LWe7"id="project-structure">Project structure<aclass="hash-link"href="#project-structure"title="Direct link to heading"></a></h2><p>The following is a description of the primary folders in Puppeteer:</p><ul><li><code>packages</code> contains all public source code.</li><li><code>test</code> contains all test source code.</li><li><code>test-d</code> contains type tests using
<ahref="https://github.com/SamVerschueren/tsd"target="_blank"rel="noopener noreferrer"><code>tsd</code></a>.</li><li><code>tools</code> contains miscellaneous scripts that are used in building and etc.</li><li><code>tools/mochaRunner</code> - contains the source code for our test runner.</li></ul><h2class="anchor anchorWithStickyNavbar_LWe7"id="api-guidelines">API guidelines<aclass="hash-link"href="#api-guidelines"title="Direct link to heading"></a></h2><p>When authoring new API methods, consider the following:</p><ul><li>Expose as little information as needed. When in doubt, don’t expose new
information.</li><li>Methods are used in favor of getters/setters.<ul><li>The only exception is namespaces, e.g. <code>page.keyboard</code> and <code>page.coverage</code></li></ul></li><li>All string literals must be small case. This includes event names and option
values.</li><li>Avoid adding "sugar" API (API that is trivially implementable in user-space)
unless they're <strong>extremely</strong> demanded.</li></ul><h2class="anchor anchorWithStickyNavbar_LWe7"id="commit-messages">Commit messages<aclass="hash-link"href="#commit-messages"title="Direct link to heading"></a></h2><p>Commit messages should follow
This is enforced via <code>npm run commitlint</code>.</p><p>In particular, breaking changes should clearly be noted as “BREAKING CHANGE:” in
the commit message footer. Example:</p><divclass="codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-text codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token plain">fix(page): fix page.pizza method</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"style="display:inline-block"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain">This patch fixes page.pizza so that it works with iframes.</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"style="display:inline-block"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain">Issues: #123, #234</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"style="display:inline-block"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain">BREAKING CHANGE: page.pizza now delivers pizza at home by default.</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain">To deliver to a different location, use the "deliver" option:</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"> `page.pizza({deliver: 'work'})`.</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2class="anchor anchorWithStickyNavbar_LWe7"id="writing-documentation">Writing documentation<aclass="hash-link"href="#writing-documentation"title="Direct link to heading"></a></h2><p>Documentation is generated via <code>npm run docs</code>. It is automatically published to
our documentation site on merge and gets versioned on release.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="writing-tsdoc-comments">Writing TSDoc comments<aclass="hash-link"href="#writing-tsdoc-comments"title="Direct link to heading"></a></h2><p>Each change to Puppeteer should be thoroughly documented using TSDoc comments.
is highly recommended!</li></ul><h2class="anchor anchorWithStickyNavbar_LWe7"id="running-the-documentation-site-locally">Running the documentation site locally<aclass="hash-link"href="#running-the-documentation-site-locally"title="Direct link to heading"></a></h2><ol><li>At root, install all dependencies with <code>npm i --ignore-scripts</code>.</li><li>run <code>npm run docs</code> which will generate all the <code>.md</code> files on
<code>puppeteer/docs/api</code>.</li><li>run <code>npm i</code> in <code>puppeteer/website</code>.</li><li>run <code>npm start</code> in <code>puppeteer/website</code>.</li></ol><h2class="anchor anchorWithStickyNavbar_LWe7"id="adding-new-dependencies">Adding new dependencies<aclass="hash-link"href="#adding-new-dependencies"title="Direct link to heading"></a></h2><p>For all dependencies (both installation and development):</p><ul><li><strong>Do not add</strong> a dependency if the desired functionality is easily
implementable.</li><li>If adding a dependency, it should be well-maintained and trustworthy.</li></ul><p>A barrier for introducing new installation dependencies is especially high:</p><ul><li><strong>Do not add</strong> installation dependency unless it's critical to project
success.</li></ul><p>There are additional considerations for dependencies that are environment
for details.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="testing-tips">Testing tips<aclass="hash-link"href="#testing-tips"title="Direct link to heading"></a></h2><ul><li>Every feature should be accompanied by a test.</li><li>Every public api event/method should be accompanied by a test.</li><li>Tests should not depend on external services.</li><li>Tests should work on all three platforms: Mac, Linux and Win. This is
especially important for screenshot tests.</li></ul><p>If a test is expected to fail on certain configurations or became flaky, update
to reflect that. See more info about TestExpectations.json in
<ahref="https://github.com/puppeteer/puppeteer/tree/main/tools/mochaRunner"target="_blank"rel="noopener noreferrer"><code>tools/mochaRunner</code></a>.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="api-coverage">API Coverage<aclass="hash-link"href="#api-coverage"title="Direct link to heading"></a></h2><p>Every public API method or event should be called at least once in tests. To
ensure this, the main <code>test</code> command runs coverage during testing.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="debugging-puppeteer">Debugging Puppeteer<aclass="hash-link"href="#debugging-puppeteer"title="Direct link to heading"></a></h2><p>See
in the readme.</p><h1>For Project Maintainers</h1><h2class="anchor anchorWithStickyNavbar_LWe7"id="rolling-new-chromium-version">Rolling new Chromium version<aclass="hash-link"href="#rolling-new-chromium-version"title="Direct link to heading"></a></h2><p>The following steps are needed to update the Chromium version.</p><ol><li>Find a suitable Chromium revision. Not all revisions have builds for all
platforms, so we need to find one that does. The easiest way is to run
<code>tools/check_availability.js -rd</code> to find the latest suitable <code>dev</code> Chromium
revision (see <code>tools/check_availability.js -help</code> for more options).</li><li>Update <code>packages/puppeteer-core/src/revisions.ts</code> with the found revision
number.</li><li>Update <code>versions.js</code> with the new Chromium-to-Puppeteer version mapping and
with the expected <code>devtools-protocol</code> version.</li><li>Run <code>npm run clean</code>, <code>npm run build</code> and <code>npm install</code>.</li><li>Run <code>npm test</code> and ensure that all tests pass. If a test fails,
<ahref="#bisecting-upstream-changes">bisect</a> the upstream cause of the failure, and
either update the test expectations accordingly (if it was an intended
change) or work around the changes in Puppeteer (if it’s not desirable to
change Puppeteer’s observable behavior).</li><li>Commit and push your changes and open a pull request. The commit message must
contain the version in <code>Chromium <version> (<revision>)</code> format to ensure
that <ahref="https://pptr.dev/"target="_blank"rel="noopener noreferrer">pptr.dev</a> can parse it correctly, e.g.
<code>'feat(chromium): roll to Chromium 90.0.4427.0 (r856583)'</code>.</li></ol><h3class="anchor anchorWithStickyNavbar_LWe7"id="bisecting-upstream-changes">Bisecting upstream changes<aclass="hash-link"href="#bisecting-upstream-changes"title="Direct link to heading"></a></h3><p>Sometimes, performing a Chromium roll causes tests to fail. To figure out the
cause, you need to bisect Chromium revisions to figure out the earliest possible
revision that changed the behavior. The <code>bisect</code> script can be helpful here.
Given a pattern for one or more unit tests, it will automatically bisect the
current range:</p><divclass="language-sh codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token plain">npm run bisect -- --good 686378 --bad 706915 script.js</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain">npm run bisect -- --unit-test Response.fromCache</span><br></span></code></pre><divclass="buttonGroup__atx"><buttontype="button"aria-label="Copy code to clipboard"title="Copy"class="clean-btn"><spanclass="copyButtonIcons_eSgA"aria-hidden="true"><svgclass="copyButtonIcon_y97N"viewBox="0 0 24 24"><pathd="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svgclass="copyButtonSuccessIcon_LjdS"viewBox="0 0 24 24"><pathd="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>By default, it will use the Chromium revision in
<code>packages/puppeteer-core/src/revisions.ts</code> from the <code>main</code> branch and from the
working tree to determine the range to bisect.</p><h2class="anchor anchorWithStickyNavbar_LWe7"id="releasing-to-npm">Releasing to npm<aclass="hash-link"href="#releasing-to-npm"title="Direct link to heading"></a></h2><p>We use <ahref="https://github.com/googleapis/release-please"target="_blank"rel="noopener noreferrer">release-please</a> to
automate releases. When a release should be done, check for the release PR in
