puppeteer/assets/js/a0d4c24a.b33efd09.js

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When called, the function executes puppeteerFunction in node.js and returns a Promise which resolves to the return value of puppeteerFunction.",source:"@site/../docs/api/puppeteer.page.exposefunction.md",sourceDirName:"api",slug:"/api/puppeteer.page.exposefunction",permalink:"/next/api/puppeteer.page.exposefunction",draft:!1,tags:[],version:"current",frontMatter:{sidebar_label:"Page.exposeFunction"},sidebar:"sidebar",previous:{title:"Page.evaluateOnNewDocument",permalink:"/next/api/puppeteer.page.evaluateonnewdocument"},next:{title:"Page.focus",permalink:"/next/api/puppeteer.page.focus"}},l={},c=[{value:"Parameters",id:"parameters",level:2},{value:"Example 1",id:"example-1",level:2},{value:"Example 2",id:"example-2",level:2}],s={toc:c};function u(e){let{components:t,...n}=e;return(0,r.kt)("wrapper",(0,a.Z)({},s,n,{components:t,mdxType:"MDXLayout"}),(0,r.kt)("h1",{id:"pageexposefunction-method"},"Page.exposeFunction() method"),(0,r.kt)("p",null,"The method adds a function called ",(0,r.kt)("inlineCode",{parentName:"p"},"name")," on the page's ",(0,r.kt)("inlineCode",{parentName:"p"},"window")," object. When called, the function executes ",(0,r.kt)("inlineCode",{parentName:"p"},"puppeteerFunction")," in node.js and returns a ",(0,r.kt)("inlineCode",{parentName:"p"},"Promise")," which resolves to the return value of ",(0,r.kt)("inlineCode",{parentName:"p"},"puppeteerFunction"),"."),(0,r.kt)("p",null,"If the puppeteerFunction returns a ",(0,r.kt)("inlineCode",{parentName:"p"},"Promise"),", it will be awaited."),(0,r.kt)("div",{className:"admonition admonition-note alert alert--secondary"},(0,r.kt)("div",{parentName:"div",className:"admonition-heading"},(0,r.kt)("h5",{parentName:"div"},(0,r.kt)("span",{parentName:"h5",className:"admonition-icon"},(0,r.kt)("svg",{parentName:"span",xmlns:"http://www.w3.org/2000/svg",width:"14",height:"16",viewBox:"0 0 14 16"},(0,r.kt)("path",{parentName:"svg",fillRule:"evenodd",d:"M6.3 5.69a.942.942 0 0 1-.28-.7c0-.28.09-.52.28-.7.19-.18.42-.28.7-.28.28 0 .52.09.7.28.18.19.28.42.28.7 0 .28-.09.52-.28.7a1 1 0 0 1-.7.3c-.28 0-.52-.11-.7-.3zM8 7.99c-.02-.25-.11-.48-.31-.69-.2-.19-.42-.3-.69-.31H6c-.27.02-.48.13-.69.31-.2.2-.3.44-.31.69h1v3c.02.27.11.5.31.69.2.2.42.31.69.31h1c.27 0 .48-.11.69-.31.2-.19.3-.42.31-.69H8V7.98v.01zM7 2.3c-3.14 0-5.7 2.54-5.7 5.68 0 3.14 2.56 5.7 5.7 5.7s5.7-2.55 5.7-5.7c0-3.15-2.56-5.69-5.7-5.69v.01zM7 .98c3.86 0 7 3.14 7 7s-3.14 7-7 7-7-3.12-7-7 3.14-7 7-7z"}))),"note")),(0,r.kt)("div",{parentName:"div",className:"admonition-content"},(0,r.kt)("p",{parentName:"div"},"Functions installed via ",(0,r.kt)("inlineCode",{parentName:"p"},"page.exposeFunction")," survive navigations."))),(0,r.kt)("p",null,(0,r.kt)("strong",{parentName:"p"},"Signature:")),(0,r.kt)("pre",null,(0,r.kt)("code",{parentName:"pre",className:"language-typescript"},"class Page {\n  exposeFunction(\n    name: string,\n    pptrFunction:\n      | Function\n      | {\n          default: Function;\n        }\n  ): Promise<void>;\n}\n")),(0,r.kt)("h2",{id:"parameters"},"Parameters"),(0,r.kt)("table",null,(0,r.kt)("thead",{parentName:"table"},(0,r.kt)("tr",{parentName:"thead"},(0,r.kt)("th",{parentName:"tr",align:null},"Parameter"),(0,r.kt)("th",{parentName:"tr",align:null},"Type"),(0,r.kt)("th",{parentName:"tr",align:null},"Description"))),(0,r.kt)("tbody",{parentName:"table"},(0,r.kt)("tr",{parentName:"tbody"},(0,r.kt)("td",{parentName:"tr",align:null},"name"),(0,r.kt)("td",{parentName:"tr",align:null},"string"),(0,r.kt)("td",{parentName:"tr",align:null},"Name of the function on the window object")),(0,r.kt)("tr",{parentName:"tbody"},(0,r.kt)("td",{parentName:"tr",align:null},"pptrFunction"),(0,r.kt)("td",{parentName:"tr",align:null},"Function ","|"," { default: Function; }"),(0,r.kt)("td",{parentName:"tr",align:null},"Callback function which will be called in Puppeteer's context.")))),(0,r.kt)("p",null,(0,r.kt)("strong",{parentName:"p"},"Returns:")),(0,r.kt)("p",null,"Promise","<","void",">"),(0,r.kt)("h2",{id:"example-1"},"Example 1"),(0,r.kt)("p",null,"An example of adding an ",(0,r.kt)("inlineCode",{parentName:"p"},"md5")," function into the page:"),(0,r.kt)("pre",null,(0,r.kt)("code",{parentName:"pre",className:"language-ts"},"const puppeteer = require('puppeteer');\nconst crypto = require('crypto');\n\n(async () => {\n  const browser = await puppeteer.launch();\n  const page = await browser.newPage();\n  page.on('console', msg => console.log(msg.text()));\n  await page.exposeFunction('md5', text =>\n    crypto.createHash('md5').update(text).digest('hex')\n  );\n  await page.evaluate(async () => {\n    // use window.md5 to compute hashes\n    const myString = 'PUPPETEER';\n    const myHash = await window.md5(myString);\n    console.log(`md5 of ${myString} is ${myHash}`);\n  });\n  await browser.close();\n})();\n")),(0,r.kt)("h2",{id:"example-2"},"Example 2"),(0,r.kt)("p",null,"An example of adding a ",(0,r.kt)("inlineCode",{parentName:"p"},"window.readfile")," function into the page:"),(0,r.kt)("pre",null,(0,r.kt)("code",{parentName:"pre",className:"language-ts"},"const puppeteer = require('puppeteer');\nconst fs = require('fs');\n\n(async () => {\n  const browser = await puppeteer.launch();\n  const page = await browser.newPage();\n  page.on('console', msg => console.log(msg.text()));\n  await page.exposeFunction('readfile', async filePath => {\n    return new Promise((resolve, reject) => {\n      fs.readFile(filePath, 'utf8', (err, text) => {\n        if (err) reject(err);\n        else resolve(text);\n      });\n    });\n  });\n  await page.evaluate(async () => {\n    // use window.readfile to read contents of a file\n    const content = await window.readfile('/etc/hosts');\n    console.log(content);\n  });\n  await browser.close();\n})();\n")))}u.isMDXComponent=!0}}]);