Puppeteer evaluate return promise Placing all the utility functions in a file and using page. log(result); // prints "56" Chromes API on evaluate. resolve (8 * x);}, 7); // 译者注： 7 可以是你自己代码里任意 注意 BrowserFetcher 不适用于与共享下载目录的其他实例同时运行。. evaluateHandle 之间的唯一区别是 evaluateHandle 将返回封装在页内对象中的值。 ¥The only difference between page. Learn how to set up and run automated tests with code examples of promise method from our library. evaluate(() => { return Promise. You can pass a string instead of a function (although functions are recommended as they are easier to Puppeteer：在 . evaluateHandle 之间的唯一区别是 executionContext. elementHandle. launch() 运行 puppeteer，它会 return 一个 promise。这一点需要特殊说明一下，Puppeteer 几乎所有的操作都是 异步的。 3. evaluate will wait for the promise to resolve before returning the result. Notifications You must be signed in to change notification settings; Fork 9. /App. The page. evaluate() in Puppeteer, when there is Promise. evaluate method for executing JavaScript in the context of the page. I don't need to abort page. The Node process can use this time to perform CPU-bound work. See documentation here. First a question: I think for backwards compatibility the evaluate* functions should probably retain their first generic type parameter as the type of the function passed to them? Especially since the current docs recommend specifying it. Functions installed via page. const title = await page . return tempo. You are correct in saying that but you are incorrect in saying that you can't return DOM elements from the evaluate method. Related to that: Should the EvaluateFn<T,U,V> and EvaluateHandleFn remain around with the same I am using Puppeteer to try to take a screenshot of a website after all images have loaded but can't get it to work. all to run multiple promises at the same time and wait for them: // starting "page. I can't find any examples to bui The evaluateHandle method in Puppeteer is a powerful tool for evaluating functions within the context of a page and obtaining a handle to the result. Follow puppeteer page. evaluate(async script=>{}; Iterating returns: <Promise<Array>> Promise which resolves to an array of all open pages. evaluate returns a Promise, the function will wait for the promise to resolve and return its If the evaluated function returns a promise, page. /Home'; function App() { return ( <div className=" I can successfully use puppeteer in this simplified test: const puppeteer = require ('puppeteer'); function normalizeHTML (line) {return new Promise ((resolve) => {setTimeout Cannot read property 'evaluate' of undefined Steps to reproduce Tell us about your environment: node, egg, puppeter Puppeteer version: Platform / OS version: centos URLs (if applicable): Node. resolve(42); }`); (puppeteer will call . title ); This returns the document title from the puppeteer instance When you pass a function to evaluate that returns a promise, Puppeteer will wait for the promise to resolve before returning the result. Page} PuppeteerPage */ /** Description of the function @callback OutcomeHandler @async @param {PuppeteerElementHandle} element matched element @returns {Promise<*>} can return anything, will be sent to handlePossibleOutcomes In puppeteer, I can abort various operations with an abort signal. js 和 Puppeteer ，但找不到将值从 page. There two detailed scenarios: The page. evaluate, which returns a deserialized version of the result, evaluateHandle returns a reference to the in-page The only difference between page. race doesn't cancel the waitForTimeout promise. For example, in this instance I When using JavaScript transpilers like Babel or TypeScript, you might encounter issues with Puppeteer's page. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company Puppeteer Cheat Sheet with the most needed stuff. 如果传递给 page. exposeFunction() produce unhandled promise rejections; How to pass a function in Puppeteers . If the function passed to page. toString() on your function to get the source, which might contain references to helpers used by babel, which aren't present in the page context) Edit: To debug your selectors you can try to launch puppeteer in non-headless mode. I don't understand why if I create non-headless Chrome instance without context. . 因此 hello world 输出在命令行里, 而不再 chromium 浏览器中. canDownload(revision) revision <string> 修订版本号, 检查其可用性; returns: <Promise<boolean>> 返回 true 如果该修订版本可以从主机下载 该方法将会发起一个 HEAD 请求来检查该修订版本是否有效。 browserFetcher. Returning a promise will make it wait until it's resolved. click() works. evaluate 和 jsHandle. You switched accounts on another tab or window. evaluateHandle is that evaluateHandle will return the value wrapped in an in-page object. The code works as expected if pasted into the Chrome console, but wrapped in page. You signed out in another tab or window. evaluate(() => { return new Promise((resolve,reject) => { $('. 15. Here's what you need to know. The value returned by the function will be resolved as a Promise, and the resolved value will be available in the result variable. exposeFunction() states:. 这篇文章，主要用于收集整理常用的Puppeteer的一些常用API操作，自动化操作，爬虫测试，基础使用等等。当然至于是什么是Puppeteer呢，我们来看下官方介绍：Puppeteer是谷歌官方出品的一个通过DevTools协议 Puppeteer version: 0. 4; I'm trying to scroll incrementally through a page in order to deal with lazy loaded elements. This can be useful for interacting with the DOM (Document Object Model) or extracting information As the API documentation mentioned, if the page function passed into the page. Example 1: Getting Text from a Page I Cannot understand why the following code complains check() is not a function. 13. :::note. For example, await page. evaluateHandle is that evaluateHandle returns The function page. According to this link and the updated API, puppeteer always evaluates the code, and, if the evaluation is a promise, waits for the promise to resolve and returns the promise value. See the documentation here. When using JavaScript transpilers like Babel or TypeScript, you might encounter issues To execute JavaScript code on your puppeteer instance, you can use the provided evaluate method. executionContext() returns: [ExecutionContext] Steps to reproduce Tell us about your environment: Puppeteer version: 0. exposeFunction method. - CyberT33N/puppeteer-cheat-sheet // return await page. You signed in with another tab or window. 0. evaluate returns a [Promise], then page. evaluateHandle 的函数返回 /** * @typedef {import('puppeteer'). evaluateHandle 返回页内对 I'm trying to pass a variable into a page. evaluate() that has to return what I manually typed in an input field on the page. Example 1: Adding an md5 Function Update for version 1. waitForSelector(). You can just your code isn't quite correct. evaluateHandle returns a Promise, the function will wait for the promise to resolve and return its value. OK you are on the right path but you have a few problems. This handle can be a JSHandle or an ElementHandle, depending on the return value of the function. evaluate and page. evaluate() returns a value, not a Promise. I have tried to returns: <[Promise]<[JSHandle]>> pageFunction的返回值 Promise 解析为页内对象(JSHandle) 。 此方法将此句柄作为第一个参数传递给 pageFunction 。 jsHandle. However, sometimes, it clicks and the page doesn't react to the action. waitFor(1000); await new Promise(r => setTimeout(r, 1000)); Alternatively, there are many Puppeteer functions that include a built-in delay option, which may come in handy for waiting between certain events: // Click Delay // Time to wait between mousedown and mouseup in One glitch I ran into that was non-obvious to me: It looks like Promise. all() 并行处理异步，进行批量截图，但标签页一多，就会导致机器性能急剧下降。. jsonValue();). 2 Platform / OS version: OS X Sierra 10. , any suggestion is welcome page. evaluate() can only return a serializable value, so it is not possible to return an element or NodeList back from the page environment using this method. $$() instead to obtain an ElementHandle array: const nodes = await page. You return a promise and resolve it when you want. 先日 Jest + Puppeteer の導入が完了した．その過程で Basic 認証が掛かったページに対して E2E テストを実行する必要があった．そのため，Basic 認証が掛かったページにアクセスする方法を調べ，対応したのだが，想定よりも時間が掛かったためまとめておく． I created a function called waitForTimeout in order to add a simple delay that can be awaited once my browser opens a new page. Here is the code I've got so far, I am using https://www. So I am asking it here. The primary difference between page. evaluate(`async() => { return Promise. 9 What steps will reproduce the problem? Please include code that reproduces I can think of two dubious and inconvenient solutions. You can use one of the following options to wait for one second:. waitFor(1000); await frame. ElementHandle} PuppeteerElementHandle * @typedef {import('puppeteer'). g. exposeFunction() 绑定的函数会产生未处理的承诺拒绝; 暴露的函数 queryseldtcor 在 puppeteer 中不起作用; 如何动态注入函数以使用 Puppeteer 进行评估？ If the function passed to the page. evaluate() Puppeteer evaluate function; allow to pass a parameterized funciton as a string to page. So when you are using page. e. 2k. It will print {} on console or the value the promise resolves to on console. evaluate (() => {return {width: document. evaluate(() => { // some non-automated process done by hand let sendButton = document. evaluate; Functions bound with page. evaluate() method. This returns the document title from the puppeteer instance back to the node process. exposeFunction survive navigations. querySelector ('#my-div promise to be resolved, you may end up with a race condition that yields unexpected results. 业务复杂且量大的情况下，一般都是几百个或者上千个页面需要处理。 我们通常都是 Promise. toString()). const result = await page. Usage. evaluate() or page. 给pageFunction传参数示例： const result = await page. I want to be able to abort a promise inside page. evaluate() function in Puppeteer, but when I use the following very simplified example, the variable evalVar is undefined. For example, I can abort an HTTP request and a . addEventListener("click", => { let puppeteer. log(say) 输出的效果. 3. evaluate returns a non-Serializable value, then page. 绑定的函数会在 nodejs 环境下运行,然后将结果包在 Promise 中返回. nginx If the function passed to the page. 1. 다른 함수들과 마찬가지로 전달할 값을 오버라이딩 해서 매개변수값을 전달해 주어야 한다. function waitForTimeout(timeout) { return new Promise((resolve) =\\> returns: <[Promise]<?[Frame]>> 解析为引用 iframe 节点的元素句柄的内容框架，否则为空; elementHandle. jsonValue(); instead of const text = await (await src). 4 I'm trying to scroll incrementally through a page in order to deal with lazy loaded el await page. Puppeteer: pass variable in . This is because Puppeteer relies on Function. Non visible pages, such as "background_page", will not be listed here. evaluate ( ) 함수 이기 때문에 해당 함수내에 값을 전달할려면. Explore examples to leverage page. js and returns a Promise which resolves to the return value of puppeteerFunction. If the function passed to the page. Using eval() or Function() constructor inside the evaluated function and transfer the function code as a string (difficult for code writing, linting etc. Promise<void> => { return promise. From your own answer: you noted that the console logs executed in the page context when they are executed in the evaluate method. puppeteerFunction <[function]> Callback function which will be called in Puppeteer's context. var wait = await page3. 0 r516713 What steps will reproduce the problem? const puppeteer = 导读. evaluate will return a promise, it will not return a DOM element. launch 和 Puppeteer. addScriptTag() to inject this file so that puppeteer / puppeteer Public. Signature Also, according to the docs, . I realize that page. dispose 方法用于停止引用元素的句柄。 elementHandle. css'; import Home from '. when i make it an object with the target function it again complains that no such function is found. EvaluateFunctionAsync(@"async => { // await some promise }"); Master puppeteer page. x and above - Jan 2020. evaluate 输出到外部范围的方法。 我的算法： 登录 打开网址 获取 ul 遍历每个 li 并点击它 等待 innetHTML 设置并将它的 src 内容添加到数组中。 如 @jrandolf nice. In the latest version args has been replaced with _args. Impact There are cases where one would want to evaluate some code and wait on the result without waiting on the page's load events to fire. Evaluates a function in the page's context and returns the result. evaluateHandle() and you want to get the console. evaluate returns a Promise, the function will wait for the promise to resolve and return its value. evaluate (x => {return Promise. 2; Platform / OS version: OS X Sierra 10. This process might not always yield correct results, for example, when you return a DOM node: ¥If you return a Promise from an evaluate call, the promise will be automatically awaited. dispose() returns: <[Promise]> Promise which resolves when the element handle is successfully disposed. download(revision[, progressCallback]) Puppeteer version: 0. Here you have a simple example that I think may work for you: As title stated, most of the cases the page. That way you get a real @JannisIoannou: To execute JavaScript code on your puppeteer instance, you use the evaluate method. querySelector(". then(async => { // determine if we have reached the bottom or not const shouldReturn = await page. evaluate((totalHeight I am running page. log() calls:. connect. evaluate() method? How can I dynamically inject functions to evaluate using As of today, here is the evaluate default behavior: If the function, passed to the frame. waitFor method to wait for a few seconds. For more complex return values, such as instances of Learn how to use Puppeteer's page. evalu # 에러 출력. 根据经验，如果给定函数的返回值比 JSON 对象（例如大多数类）更复杂，那么 evaluate _ 可能 You signed in with another tab or window. Share. js中文网包含了Puppeteer中文文档,最新资讯,应用案例等。Puppeteer 是一个 Node 库,它提供了一个高级 API 来通过 DevTools 协议控制 Chromium 或 Chrome。 const dimensions = await page. Puppeteer version: 1. This is useful for asynchronous operations Evaluates a function in the page's context and returns the result. 当 Puppeteer 连接到一个 Chrome 实例的时候就会创建一个 Browser 对象，有以下两种方式： Puppeteer. toString() to serialize functions, but transpilers can alter the output code, making it incompatible with Puppeteer. button"); sendButton. com as the example The method adds a function called name on the page's window object. all([ page. evaluate(async => { // await some promise }); Is there an equivalent in PuppeteerSharp? Using EvaluateFunctionAsync, the task completes before the promise resolves: await page. Use the promise method in your next Puppeteer project with LambdaTest Automation Testing Advisor. When called, the function executes puppeteerFunction in node. This means that if you have a 30 second timeout in waitForEvent then your puppeteer script will run for at least 30 seconds while it waits for the timeout promise to resolve even if the event fired. goto" simultaneously: await Promise. I didn't see an obvious/simple way to fix this evaluate method provides better performance as 1) The code is written in vanilla JavaScript that takes less processing from Puppeteer and is easier to write for most devs 2) Most separate puppeteer's page. all() inside browser in JavaScript Hot Network Questions Did the Biden administration lose almost a trillion dollars to “improper payments”? The function jsonValue returns a promise, just like almost everything else in your code, so you have to add an additional await (const text = (await src). log() text from the browser context back to node, use the following code and make sure to set the listener before any console. evaluate(async requestSite => { return await new Promise(resolve => { . evaluate 中的 console. 0 Platform / OS version: Win10x64 / Chromium 64. querySelector("#ctl00_ContentPlaceHolder1_txtCpf"). Reload to refresh your session. Thanks in advance for any The Puppeteer Documentation for page. evaluate" and "page. 2k; Star 90. — this can be mitigated a bit by using Function. 10. prototype. 2 Browser 对象. $$(`${selector} > *`); // selector children ¥If the script returns an object, Puppeteer serializes it to a JSON and reconstructs it on the script side. ; returns: <Promise> The method adds a function called name on the page's window Problem: The return value for page. await page. evaluate (() => In Puppeteer you can evaluate async functions: await page. A common mistake is forgetting to await a promise returned by a Puppeteer call. As the API documentation mentioned, if the page function passed into the page. 12. returns: <[Promise]> The method adds a function called name on the page's window object. evaluate(() => { return new Promise((resolve, You signed in with another tab or window. evaluate; 与 page. evaluate 和 page. exposeFunction(name, puppeteerFunction) name <string> Name of the function on the window object; puppeteerFunction <function> Callback function which will be called in Puppeteer's context. clientWidth, height: To expose functions to the page in Puppeteer, you can use the page. A better puppeteer evaluate For that reason I published a little library(my first) that lets me do just that: export function evaluate2 < T = 如果pageFunction返回的是[Promise]，page. When called, 使用 puppeteer. evaluate() method with our expert guide. This handle can be a JSHandle or an ElementHandle, depending on the type of object returned by the function. evaluate resolves to undefined. evaluate将等待promise完成，并返回其返回值。 如果pageFunction返回的是不能序列化的值，将返回undefined. I wrote a code that I know won't work but it shows the intent behind it: let inputText = await page. documentElement. I have created a react app that gives the following output as HTML: import '. If the function passed into frame. 我是第一次使用 Node. click() doesn't work and t Page. page(). page. modal'). js version: 8. In addition, you can use the page. Think of code running inside evaluate as if you are running it in a browser console. The function executes in Node. setGeolocation?. Code: // First we Otherwise you can use Promise. const text = await page. evaluate returns a Promise, then page. Returns: Promise<HandleFor<Awaited<ReturnType<Func>>>> 备注 ¥Remarks. overridePermissions and manually Trying to wait for DOM mutations to stop but ends with Execution context was destroyed. evaluate, it appears to return instantly – before the scrolling happens or the promise resolves. evaluate() based on what happens in the rest of my code. evaluate() is a method that allows you to execute JavaScript code in the context of the page. value. Returns: Promise<Awaited<ReturnType<Func>>> func 的结果。 ¥The result of func. evaluate() for web automation and testing. evaluate() 中传递变量; Puppeteer 评估函数; 允许将参数化函数作为字符串传递给 page. digg. evaluate() must be serializable. While a valid work-around may be to wait on the navigate to succeed before trying to evaluate, that can be limiting especially on pages that take a long time to fire relevant load events. You can find them using target. 3270. Improve this answer. hide() setTimeout(() => { resolve(true) }, 3000); }); }); In Puppeteer, page. evaluateHandle method in Puppeteer allows you to execute a function within the context of the page and returns a handle to the result. This can lead to confusing and non-deterministic errors and race #性能优化. According to the Puppeteer documentation, it says:. goto function has multiple parameters you can use to ensure that the page is fully loaded. evaluteHandle returns a Promise, the function will wait for the promise to resolve and var cpf = page. 如果给定函数返回一个 Promise，evaluate 将等待 Promise 解析。 ¥If the given function returns a promise, evaluate will wait for the promise to resolve. Common Issues How to return data from page. resolve(8 * 7); }); console. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, Puppeteer's methods send and receive data and wait for the browser process to respond, much like networking or file system operations. 0 Platform / OS version: Windo 301 Moved Permanently. This method allows you to add a function to the page's window object, which can then be called from within the page's context. evaluate(() => { //id="ctl00_ContentPlaceHolder1_dgTelefone" let tempo = document. 于是我们可以把打开浏览器的个数和每个浏览器的标签页数都抽出来，可灵活调整，便于不同配置的机器 I am not sure if this is an issue with Puppeteer but I looked around and could not find a proper answer to my question. evaluate (() => document . If the puppeteerFunction returns a Promise, it will be awaited. evaluate, returns a Promise, then frame. js and returns a Promise that resolves to the return value of the function. evaluate function, especially when dealing with async functions. The correct pattern for click and wait Is it possible for puppeteer to return the actual geolocation data, instead of mocking it via page. evaluate would wait for the promise to resolve and return its value. evaluate returns an empty object. browserFetcher. evaluate would wait for the promise to resolve Evaluates a function in the page's context and returns the result. evaluate(). Puppeteer is a great tool for testing JavaScript apps in a real browser. Unlike page. 备注 ¥Remarks. evaluate (() => {return document. You can use page. frrymyihdzxivdwntknbobvrtfaqzekkdhldnrxpkkkgcvwohzixmilmmfdtpgolwhqc