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<title data-rh="true">Contributing | Puppeteer</title><meta data-rh="true" name="viewport" content="width=device-width,initial-scale=1"><meta data-rh="true" name="twitter:card" content="summary_large_image"><meta data-rh="true" property="og:url" content="https://pptr.dev/next/contributing"><meta data-rh="true" name="docsearch:language" content="en"><meta data-rh="true" name="docsearch:counter" content="3"><meta data-rh="true" property="og:title" content="Contributing | Puppeteer"><meta data-rh="true" name="description" content="First of all, thank you for your interest in Puppeteer! We&#x27;d love to accept your"><meta data-rh="true" property="og:description" content="First of all, thank you for your interest in Puppeteer! We&#x27;d love to accept your"><link data-rh="true" rel="icon" href="/img/favicon.ico"><link data-rh="true" rel="canonical" href="https://pptr.dev/next/contributing"><link data-rh="true" rel="alternate" href="https://pptr.dev/next/contributing" hreflang="en"><link data-rh="true" rel="alternate" href="https://pptr.dev/next/contributing" hreflang="x-default"><link data-rh="true" rel="preconnect" href="https://DVKY664LG7-dsn.algolia.net" crossorigin="anonymous"><link rel="search" type="application/opensearchdescription+xml" title="Puppeteer" href="/opensearch.xml">
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patches and contributions!</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="contributor-license-agreement">Contributor License Agreement<a class="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 <a href="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&#x27;ve already submitted one
(even if it was for a different project), you probably don&#x27;t need to do it
again.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="getting-started">Getting started<a class="hash-link" href="#getting-started" title="Direct link to heading"></a></h2><ol><li><p>Clone this repository</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">git clone https://github.com/puppeteer/puppeteer</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">cd puppeteer</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>or</p><p><a href="https://github.com/codespaces/new?hide_repo_select=true&amp;ref=main&amp;repo=90796663&amp;machine=standardLinux32gb&amp;devcontainer_path=.devcontainer%2Fdevcontainer.json" target="_blank" rel="noopener noreferrer"><img loading="lazy" src="https://github.com/codespaces/badge.svg" alt="Open in GitHub Codespaces" class="img_ev3q"></a></p></li><li><p>Install the dependencies</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm install</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"># Or to download Firefox</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">PUPPETEER_PRODUCT=firefox npm install</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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>Build all packages</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm run build</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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>Run all tests</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlo
Chromium version installed locally (you only need to do this once, not on
every test run) and then you can run the tests:</p><div class="language-bash codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token assign-left variable" style="color:#36acaa">PUPPETEER_EXPERIMENTAL_CHROMIUM_MAC_ARM</span><span class="token operator" style="color:#393A34">=</span><span class="token number" style="color:#36acaa">1</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">npm</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">install</span><span class="token plain"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"></span><span class="token assign-left variable" style="color:#36acaa">PUPPETEER_EXPERIMENTAL_CHROMIUM_MAC_ARM</span><span class="token operator" style="color:#393A34">=</span><span class="token number" style="color:#36acaa">1</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">npm</span><span class="token plain"> run </span><span class="token builtin class-name">test</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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><div class="language-bash codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token assign-left variable" style="color:#36acaa">BINARY</span><span class="token operator" style="color:#393A34">=</span><span class="token operator" style="color:#393A34">&lt;</span><span class="token plain">path-to-chrome/firefox-executable</span><span class="token operator" style="color:#393A34">&gt;</span><span class="token plain"> </span><span class="token function" style="color:#d73a49">npm</span><span class="token plain"> run test:chrome </span><span class="token comment" style="color:#999988;font-style:italic"># Or npm run test:firefox</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></li></ul><h2 class="anchor anchorWithStickyNavbar_LWe7" id="building-a-single-package">Building a single package<a class="hash-link" href="#building-a-single-package" title="Direct link to heading"></a></h2><p>To build a single package, you can run:</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm run build --workspace &lt;package&gt; # e.g. puppeteer</sp
packages is sufficient. This is all possible due to
<a href="https://github.com/google/wireit" target="_blank" rel="noopener noreferrer">wireit</a> which behaves similar to
<a href="https://www.gnu.org/software/make/" target="_blank" rel="noopener noreferrer">GNU Make</a>.</p><h3 class="anchor anchorWithStickyNavbar_LWe7" id="watch-mode">Watch mode<a class="hash-link" href="#watch-mode" title="Direct link to heading"></a></h3><p>To continuously build a package, you can run:</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm run build --watch --workspace &lt;package&gt; # e.g. puppeteer</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><p>You have to only specify a single package to watch else things will not work as expected
As stated above because of <a href="https://github.com/google/wireit" target="_blank" rel="noopener noreferrer">wireit</a> when a change happens
all dependencies will be build or rebuild (if needed).</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="removing-stale-artifacts">Removing stale artifacts<a class="hash-link" href="#removing-stale-artifacts" title="Direct link to heading"></a></h2><p>It&#x27;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><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm run clean # or npm run clean --workspace &lt;package&gt;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2 class="anchor anchorWithStickyNavbar_LWe7" id="comprehensive-testing">Comprehensive testing<a class="hash-link" href="#comprehensive-testing" title="Direct link to heading"></a></h2><p>Outside of <code>npm test</code>, there are several other
<a href="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
<a href="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
<a href="https://github.com/puppeteer/puppeteer/blob/main/test/TestExpectations.json" target="_blank" rel="noopener noreferrer">TestExpectations.json</a>
to see if a given test result is expected or not. See more info about the test
runner in
<a href="https://github.com/puppeteer/puppeteer/tree/main/tools/mochaRunner" target="_blank" rel="noopener noreferrer"><code>tools/mochaRunner</code></a>.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="code-reviews">Code reviews<a class="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
<a href="https://help.github.com/articles/about-pull-requests/" target="_blank" rel="noopener noreferrer">GitHub Help</a> for more
information on using pull requests.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="code-style">Code Style<a class="hash-link" href="#code-style" title="Direct link to heading"></a></h2><p>Our coding style is fully defined in
<a href="https://github.com/puppeteer/puppeteer/blob/main/.eslintrc.js" target="_blank" rel="noopener noreferrer"><code>.eslintrc</code></a>
(<a href="https://eslint.org/" target="_blank" rel="noopener noreferrer">ESLint</a>) and
<a href="https://github.com/puppeteer/puppeteer/blob/main/.prettierrc.cjs" target="_blank" rel="noopener noreferrer"><code>.prettierrc.cjs</code></a>
(<a href="https://prettier.io" target="_blank" rel="noopener noreferrer">Prettier</a>).</p><p>Code is checked during <code>pre-push</code> using
<a href="https://typicode.github.io/husky/#/" target="_blank" rel="noopener noreferrer">Husky</a>, but you can check your code
manually by running:</p><div class="language-bash codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token function" style="color:#d73a49">npm</span><span class="token plain"> run lint</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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><div class="language-bash codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-bash codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token function" style="color:#d73a49">npm</span><span class="token plain"> run </span><span class="token function" style="color:#d73a49">format</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2 class="anchor anchorWithStickyNavbar_LWe7" id="project-structure">Project structure<a class="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
<a href="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><h2 class="anchor anchorWithStickyNavbar_LWe7" id="api-guidelines">API guidelines<a class="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, dont 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 &quot;sugar&quot; API (API that is trivially implementable in user-space)
unless they&#x27;re <strong>extremely</strong> demanded.</li></ul><h2 class="anchor anchorWithStickyNavbar_LWe7" id="commit-messages">Commit messages<a class="hash-link" href="#commit-messages" title="Direct link to heading"></a></h2><p>Commit messages should follow
<a href="https://www.conventionalcommits.org/en/v1.0.0/#summary" target="_blank" rel="noopener noreferrer">the Conventional Commits format</a>.
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><div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">fix(page): fix page.pizza method</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">This patch fixes page.pizza so that it works with iframes.</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">Issues: #123, #234</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">BREAKING CHANGE: page.pizza now delivers pizza at home by default.</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">To deliver to a different location, use the &quot;deliver&quot; option:</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain"> `page.pizza({deliver: &#x27;work&#x27;})`.</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2 class="anchor anchorWithStickyNavbar_LWe7" id="writing-documentation">Writing documentation<a class="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><h2 class="anchor anchorWithStickyNavbar_LWe7" id="writing-tsdoc-comments">Writing TSDoc comments<a class="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.
Refer to the
<a href="https://api-extractor.com/pages/tsdoc/doc_comment_syntax/" target="_blank" rel="noopener noreferrer">API Extractor documentation</a>
for information on the exact syntax.</p><ul><li>Every new method needs to have either <code>@public</code> or <code>@internal</code> added as a tag
depending on if it is part of the public API.</li><li>Keep each line in a comment to no more than 90 characters (ESLint will warn
you if you go over this). If you&#x27;re a VSCode user the
<a href="https://marketplace.visualstudio.com/items?itemName=stkb.rewrap" target="_blank" rel="noopener noreferrer">Rewrap plugin</a>
is highly recommended!</li></ul><h2 class="anchor anchorWithStickyNavbar_LWe7" id="running-the-documentation-site-locally">Running the documentation site locally<a class="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><h2 class="anchor anchorWithStickyNavbar_LWe7" id="adding-new-dependencies">Adding new dependencies<a class="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&#x27;s critical to project
success.</li></ul><p>There are additional considerations for dependencies that are environment
agonistic. See the
<a href="https://github.com/puppeteer/puppeteer/blob/main/third_party/README.md" target="_blank" rel="noopener noreferrer"><code>third_party/README.md</code></a>
for details.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="testing-tips">Testing tips<a class="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
<a href="https://github.com/puppeteer/puppeteer/blob/main/test/TestExpectations.json" target="_blank" rel="noopener noreferrer">TestExpectations.json</a>
to reflect that. See more info about TestExpectations.json in
<a href="https://github.com/puppeteer/puppeteer/tree/main/tools/mochaRunner" target="_blank" rel="noopener noreferrer"><code>tools/mochaRunner</code></a>.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="api-coverage">API Coverage<a class="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><h2 class="anchor anchorWithStickyNavbar_LWe7" id="debugging-puppeteer">Debugging Puppeteer<a class="hash-link" href="#debugging-puppeteer" title="Direct link to heading"></a></h2><p>See <a href="https://pptr.dev/guides/debugging" target="_blank" rel="noopener noreferrer">Debugging Tips</a>.</p><h1>For Project Maintainers</h1><h2 class="anchor anchorWithStickyNavbar_LWe7" id="rolling-new-chromium-version">Rolling new Chromium version<a class="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
update <code>lastMaintainedChromiumVersion</code> with the latest stable Chrome version.
You can find the corresponding version by going to <a href="https://omahaproxy.appspot.com/" target="_blank" rel="noopener noreferrer">omahaproxy.appspot.com</a> then
searching in <code>Find Releases</code> for <code>r&lt;revision&gt;</code>.</li><li>Run <code>npm run check</code>. If it fails, update
<code>packages/puppeteer-core/package.json</code> and <code>packages/puppeteer/package.json</code>
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,
<a href="#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 its not desirable to
change Puppeteers observable behavior).</li><li>Commit and push your changes and open a pull request. The commit message must
contain the version in <code>Chromium &lt;version&gt; (r&lt;revision&gt;)</code> format to ensure
that <a href="https://pptr.dev/" target="_blank" rel="noopener noreferrer">pptr.dev</a> can parse it correctly, e.g.
<code>&#x27;feat(chromium): roll to Chromium 90.0.4427.0 (r856583)&#x27;</code>.</li></ol><h3 class="anchor anchorWithStickyNavbar_LWe7" id="bisecting-upstream-changes">Bisecting upstream changes<a class="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><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm run bisect -- --good 686378 --bad 706915 script.js</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">npm run bisect -- --unit-test Response.fromCache</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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><h2 class="anchor anchorWithStickyNavbar_LWe7" id="releasing-to-npm">Releasing to npm<a class="hash-link" href="#releasing-to-npm" title="Direct link to heading"></a></h2><p>We use <a href="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
our <a href="https://github.com/puppeteer/puppeteer/pulls" target="_blank" rel="noopener noreferrer">pull requests</a> and merge it.</p><h3 class="anchor anchorWithStickyNavbar_LWe7" id="in-case-release-please-fails">In case Release Please fails<a class="hash-link" href="#in-case-release-please-fails" title="Direct link to heading"></a></h3><p>In the event release-please fails, the following needs to be done:</p><ol><li><p>Update anything missing in the CHANGELOG of every package that was supposed
to be published. For example, if the header is missing, you may need to add</p><ul><li><p>For puppeteer:</p><div class="language-md codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-md codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token title important punctuation" style="color:#393A34">##</span><span class="token title important"> [{NEW_VERSION}](https://github.com/puppeteer/puppeteer/compare/v{PREVIOUS_VERSION}...v{NEW_VERSION}) ({CURRENT_DATE})`</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="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>For other packages:</p><div class="language-md codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-md codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token title important punctuation" style="color:#393A34">##</span><span class="token title important"> [{NEW_VERSION}](https://github.com/puppeteer/puppeteer/compare/{PACKAGE_FOLDER_NAME}-v{PREVIOUS_VERSION}...{PACKAGE_FOLDER_NAME}-v{NEW_VERSION}) ({CURRENT_DATE})</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="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><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></li></ul></li><li><p>Create a GitHub release for each package, following the practice of previous
releases.</p></li></ol><h2 class="anchor anchorWithStickyNavbar_LWe7" id="bug-triage-guidelines">Bug triage guidelines<a class="hash-link" href="#bug-triage-guidelines" title="Direct link to heading"></a></h2><p><a href="https://github.com/puppeteer/puppeteer/issues" target="_blank" rel="noopener noreferrer">Check incoming bug reports</a> that do not have a <code>confirmed</code> or <code>needs-feedback</code> label:</p><ol><li>Make sure the issue is labeled as either <code>bug</code> or <code>feature</code>.</li><li>If the issue does not have a clear repro or you cannot repro, ask for the repro and set the <code>needs-feedback</code> label.</li><li>Follow-up on the issues you previously asked for a feedback on (you should get a notification on GitHub when the user responds).</li><li>If the user does not provide feedback, the issue will be closed by the stale bot eventually.</li><li>If you are able to reproduce the issue, add the label <code>confirmed</code>.</li><li>If the bug is on the Chromium side, create a corresponding crbug.com issue, label the GitHub issue with the <code>upstream</code> label, and post a link to crbug.com in the comments.</li><li>If the issue is not related to either Puppeteer or Chromium, close the issue.</li><li>If the issue is about missing/incorrect documentation, label it as <code>documentation</code>.</li></ol><p>Issues with PDFs:</p><ol><li>If the issue reproduces using the regular print dialog and/or headful, <a href="https://bugs.chromium.org/p/chromium/issues/entry?components=Blink%3ELayout" target="_blank" rel="noopener noreferrer">file a crbug.com against the <code>Blink&gt;Layout</code> component</a>.</li><li>If the issue is specific to Headless mode, <a href="https://bugs.chromium.org/p/chromium/issues/entry?components=Internals%3EHeadless" target="_blank" rel="noopener noreferrer">file an issue on crbug.com against the <code>Internals&gt;Headless</code> component</a>.</li></ol></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages navigation"><a class="pagination-nav__link pagination-nav__link--prev" href="/next/troubleshooting"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">Troubleshooting</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/next/faq"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">FAQ</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#contributor-license-agreement" class="table-of-contents__link toc-highlight">Contributor License Agreement</a></li><li><a href="#getting-started" class="table-of-contents__link toc-highlight">Getting started</a><ul><li><a href="#macos-arm-and-custom-executables" class="table-of-contents__link toc-highlight">macOS ARM and custom executables.</a></li></ul></li><li><a href="#building-a-single-package" class="table-of-contents__link toc-highlight">Building a single package</a><ul><li><a href="#watch-mode" class="table-of-contents__link toc-highlight">Watch mode</a></li></ul></li><li><a href="#removing-stale-artifacts" class="table-of-contents__link toc-highlight">Removing stale artifacts</a></li><li><a href="#comprehensive-testing" class="table-of-contents__link toc-highlight">Comprehensive testing</a></li><li><a href="#code-reviews" class="table-of-contents__link toc-highlight">Code reviews</a></li><li><a href="#code-style" class="table-of-contents__link toc-highlight">Code Style</a></li><li><a href="#project-structure" class="table-of-contents__link toc-highlight">Project structure</a></li><li><a href="#api-guidelines" class="table-of-contents__link toc-highlight">API guidelines</a></li><li><a href="#commit-messages" class="table-of-contents__link toc-highlight">Commit messages</a></li><li><a href="#writing-documentation" class="table-of-contents__link toc-highlight">Writing documentation</a></li><li><a href="#writing-tsdoc-comments" class="table-of-contents__link
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