<titledata-rh="true">Evaluate JavaScript | 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/guides/evaluate-javascript"><metadata-rh="true"name="docsearch:language"content="en"><metadata-rh="true"name="docsearch:counter"content="3"><metadata-rh="true"property="og:title"content="Evaluate JavaScript | Puppeteer"><metadata-rh="true"name="description"content="Puppeteer allows evaluating JavaScript functions in the context of the page"><metadata-rh="true"property="og:description"content="Puppeteer allows evaluating JavaScript functions in the context of the page"><linkdata-rh="true"rel="icon"href="/img/favicon.ico"><linkdata-rh="true"rel="canonical"href="https://pptr.dev/next/guides/evaluate-javascript"><linkdata-rh="true"rel="alternate"href="https://pptr.dev/next/guides/evaluate-javascript"hreflang="en"><linkdata-rh="true"rel="alternate"href="https://pptr.dev/next/guides/evaluate-javascript"hreflang="x-default"><linkdata-rh="true"rel="preconnect"href="https://DVKY664LG7-dsn.algolia.net"crossorigin="anonymous"><linkrel="search"type="application/opensearchdescription+xml"title="Puppeteer"href="/opensearch.xml">
stringified by Puppeteer, sent to the target page over Chrome DevTools protocol
and evaluated there. It means that the function cannot access scope variables in
your script.</p></div></div><p>Alternatively, you can provide a function body as a string:</p><divclass="language-ts codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-ts codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token comment"style="color:#999988;font-style:italic">// Evaluate JavaScript</span><spanclass="token plain"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"></span><spanclass="token keyword"style="color:#00009f">const</span><spanclass="token plain"> three </span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token plain"></span><spanclass="token keyword"style="color:#00009f">await</span><spanclass="token plain"> page</span><spanclass="token punctuation"style="color:#393A34">.</span><spanclass="token function"style="color:#d73a49">evaluate</span><spanclass="token punctuation"style="color:#393A34">(</span><spanclass="token template-string template-punctuation string"style="color:#e3116c">`</span><spanclass="token template-string string"style="color:#e3116c"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token template-string string"style="color:#e3116c"> 1 + 2</span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token template-string string"style="color:#e3116c"></span><spanclass="token template-string template-punctuation string"style="color:#e3116c">`</span><spanclass="token punctuation"style="color:#393A34">)</span><spanclass="token punctuation"style="color:#393A34">;</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><divclass="theme-admonition theme-admonition-caution alert alert--warning admonition_LlT9"><divclass="admonitionHeading_tbUL"><spanclass="admonitionIcon_kALy"><svgviewBox="0 0 16 16"><pathfill-rule="evenodd"d="M8.893 1.5c-.183-.31-.52-.5-.887-.5s-.703.19-.886.5L.138 13.499a.98.98 0 0 0 0 1.001c.193.31.53.501.886.501h13.964c.367 0 .704-.19.877-.5a1.03 1.03 0 0 0 .01-1.002L8.893 1.5zm.133 11.497H6.987v-2.003h2.039v2.003zm0-3.004H6.987V5.987h2.039v4.006z"></path></svg></span>caution</div><divclass="admonitionContent_S0QG"><p>The example above produces the equivalent results but it also illustrates that
the types and global variables available to the evaluated function cannot be
known. Especially, in TypeScript you should be careful to make sure that objects
referenced by the evaluated function are correct.</p></div></div><h2class="anchor anchorWithStickyNavbar_LWe7"id="return-types">Return types<aclass="hash-link"href="#return-types"title="Direct link to heading"></a></h2><p>The functions you evaluate can return values. If the returned value is of a
primitive type, it gets automatically converted by Puppeteer to a primitive type
in the script context like in the previous example.</p><p>If the script returns an object, Puppeteer serializes it to a JSON and reconstructs it on the script side. This process might not always yield correct results, for example, when you return a DOM node:</p><divclass="language-ts codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-ts codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token keyword"style="color:#00009f">const</span><spanclass="token plain"> body </span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token plain"></span><spanclass="token keyword"style="color:#00009f">await</span><spanclass="token plain"> page</span><spanclass="token punctuation"style="color:#393A34">.</span><spanclass="token function"style="color:#d73a49">evaluate</span><spanclass="token punctuation"style="color:#393A34">(</span><spanclass="token punctuation"style="color:#393A34">(</span><spanclass="token punctuation"style="color:#393A34">)</span><spanclass="token plain"></span><spanclass="token operator"style="color:#393A34">=></span><spanclass="token plain"></span><spanclass="token punctuation"style="color:#393A34">{</span><spanclass="token plain"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"></span><spanclass="token keyword"style="color:#00009f">return</span><spanclass="token plain"> document</span><spanclass="token punctuation"style="color:#393A34">.</span><spanclass="token plain">body</span><spanclass="token punctuation"style="color:#393A34">;</span><spanclass="token plain"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"></span><spanclass="token punctuation"style="color:#393A34">}</span><spanclass="token punctuation"style="color:#393A34">)</span><spanclass="token punctuation"style="color:#393A34">;</span><spanclass="token plain"></span><br></span><spanclass="token-line"style="color:#393A34"><spanclass="token plain"></span><spanclass="token builtin">console</span><spanclass="token punctuation"style="color:#393A34">.</span><spanclass="token function"style="color:#d73a49">log</span><spanclass="token punctuation"style="color:#393A34">(</span><spanclass="token plain">body</span><spanclass="token punctuation"style="color:#393A34">)</span><spanclass="token punctuation"style="color:#393A34">;</span><spanclass="token plain"></span><spanclass="token comment"style="color:#999988;font-style:italic">// {}, unexpected!</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>To work with the returned objects, Puppeteer offers a way to return objects by reference:</p><divclass="language-ts codeBlockContainer_Ckt0 theme-code-block"style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><divclass="codeBlockContent_biex"><pretabindex="0"class="prism-code language-ts codeBlock_bY9V thin-scrollbar"><codeclass="codeBlockLines_e6Vv"><spanclass="token-line"style="color:#393A34"><spanclass="token keyword"style="color:#00009f">const</span><spanclass="token plain"> body </span><spanclass="token operator"style="color:#393A34">=</span><spanclass="token plain"></span><spanclass="token keyword"style="color:#00009f">await</span><spanclass="token plain"> page</span><spanclass="token punctuation"style="color:#393A34">.</span><spanclass="tokenfun
