Puppeteer pass function to evaluate Puppeteer: How to evaluate xpath with document. appendFileSync with that: You are not returning any data from the page. It signals to the web browser a string called a "fragment" that targets an anchor on a web page. evaluate() run in the browser's context which is not the context of where anum and articleHTML are defined (the node. Description. Take a look at the function itself, the selG variable doesn't exist so the let gp = document. 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. I pass in an variable array that I would like to use to retrieve links from these sections in a drop down. evaluate() called on them) are followed to the DOM node in the browser that they represent, and that DOM node is what your evaluate's callback is invoked with. Quoting directly the Puppeteer docs How can I pass variable into an evaluate function that evaluates an async function using Puppeteer? Hot Network Questions Is this version of Zorn's lemma provable in ZF? My goal is to open puppeteer-chromium instance as a child process in nodejs environment and listen to all clicks that user will make in a way that these events are accessible from Is it possible to pass a function to Puppeteer's page. exposeFunction makes it easier to pass data back to Node from your MutationObserver or trigger a callback than console. When sending a string instead of the function, the prints do print the string itself, and not null. Commented Aug 27, 2020 at 21:20. js version: v10. evaluate(), but when I run the script it throws a following error: Error: Evaluation failed: TypeError: Cannot read property 'p1' of undefined. evaluate() is not working. In these cases, you may prefer the evaluate approach, or only partially converting the browser code to Puppeteer code on an as-needed basis for specific trusted events. evaluate is run in the browser context, so the console. Error: Evaluation failed: ReferenceError: value is not defined My code bellow. view-source: is the place to look for statically-present elements (and when JS runs, some of those elements may be changed or removed, I want to pass the for loop variable to page. It always reports Pass a function to evaluate() in puppeteer. other one is the chromium browser and those contexts run in different processes and don't share memory except when you pass variables via the puppeteer api. evaluate() runs in the context of the web page puppeteer is running in, so of course it doesn't know what fs is. evaluate(async => { // await some promise }); Is there an equivalent in PuppeteerSharp? Using EvaluateFunctionAsync, the task . It can be tested on try-puppeteer, just copy and paste my code and remove the require statement. How to await an async function evaluation in PuppeteerSharp. Thanks a bunch! I'm getting awfully confused with all the different ways to pass parameters in puppeteer (migrating from casperjs and phantomjs), so this sure helps (I also just discovered I can invoke the eval methods directly on my JSHandle object,which will definitely help (need to build an agGrid library to manipulate agGrid objects to test with jestJS) I'm trying to do several tests with Puppeteer sharp but it's the first time that I work with it and I don't have very clear the syntax. exposeFunction() states:. const selector = '#someSelector'; // 2. selector to query the page for. In fact this is the method signature: page. evaluate() method? How can I dynamically inject functions to evaluate using Puppeteer? The only difference between page. evaluate() is a method that allows you to execute JavaScript code in the context of the page. js script scope. Undefined Variables Contribute to puppeteer/puppeteer development by creating an account on GitHub. ; returns: <Promise> The method adds a function called name on the page's window I am trying to evaluate a function with puppeteer but the callback is never firing (i am certain the host page is working as expected). evaluate will be executed in a browser (just as if you opened a fresh browser, pressed F12 and pasted your code in Devtools console). I hate redefining things but it works as You should pass arguments after evaluate arrow function. If you post the predicted code i can suggest you a better way. resolve()` - stops passing `awaitPromise` parameter to `Runtime. evaluateHandle is that evaluateHandle will return the value wrapped in an in-page object. js module! Everything else that you write in your code is executed not in a browser but in node. Since you're passing usedLicenses as an argument to evaluate(), you can access it inside the evaluate function directly by referencing it within the function's scope. evaluate isn't a part of you code, and you can't call a function of your code from it. If you want to pass a parameter to a function via the query string of the URL, it should be URL escaped with percent encoding. 1 I am a newbie in puppeteer and I can't understand why the following code cannot work. To achieve this, it's essential to Puppeteer: pass variable in . I use exposeFunction and I need to send the full Element to my function I have a simple example: const puppeteer = require either pass only the string and object without any circular reference, or use puppeteers ElementHandle to handle the elements. Improve this answer. evaluate call. I have defi Is it possible to pass a function to Puppeteer's page. You have to explicitly pass the function into the context like this: I've found that it's possible to pass a variable using the page. Evaluate Function: Within page. So, with that encoding, your URL parameter would be selector=%23hplogo. launch({args: ['--no-sandbox', '--disable-setuid-sandbox'], Skip to main content Take a a look at the Puppeteer documentation for page. like this page. Puppeteer: use function inside page. tweet') is an array of elementHandle. ) is running on every DOMMutation from the puppeteer option polling: "mutation". 2 Platform / OS version: Windows 10, Node 8. Function itself has it's own scope of visibility. Consider the following example: I'm trying to render a page using puppeteer, extract the name of a dynamic javascript variable on the page, and return the variable as an object. This can be useful for interacting with the DOM (Document Object Model) or extracting information Learn how to use Puppeteer's evaluate function to pass objects and execute scripts in the browser context. If you want to call a function from inside the evaluate function, usually (but not in this case) you can use one of this tricks: How to pass a function in Puppeteers . If the function passed to the page. title ); This returns the document title from the puppeteer instance All I want is to be able to pass a parameterised function as a string to the page. How can I pass an existing object into Puppeteer's page. Here is a pretty simple example, and maybe somebody can see if i'm just doing something stupid here. src) })) Explanation: Arrow function You signed in with another tab or window. Try this: A better puppeteer evaluate For that reason I published a little library(my first) that lets me do just that: Aptly named puppeteer-evaluate2, it allows me to write my puppeteer callback code like any other JavaScript code, where closures/imports are In Puppeteer you can evaluate async functions: await page. ReferenceError: alljobs is not defined. 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) Is it possible to pass a function to Puppeteer's page. evaluate puppeteer evaluate functions not accepting JSHandles or ElementHandles as variables. — this can be mitigated a bit by In Puppeteer, page. : await page. With page. log(evalVar); // should be defined now }, evalVar); await can only be used in async functions. type('input[type="email"]', loginData. Does request exist there? No, it's a node. I’m not familiar with pupeteer at all but by looking at the documentation for that function, there may be something you can try. /scraper. what’s happening here is that I am passing i as an argument to the function. Here is the puppeteer function(th (page){ await page. evaluate() function, you need to ensure that the variable is correctly referenced within the function. Inside the second function I'm trying to console log the value of value but I get . another-element") awai page. How to pass array and function to Page. evaluate It synchronously creates the interval, and then the whole function that you pass to page. Type. log as a trigger here is a strange choice. evaluate in Puppeteer with Jest? 2. 4. Note that the variables must be serializable: I'm building a web scraper, which has series of function calls passing around a puppeteer page object with the css selector string, to extract that html object and apply some arbitrary modification on it, provided as a function efn. How would I go about this function? Meaning predicate (the function that is being sent) is being recognized as null. evaluate, call the md5 function to hash a string and log the result to the console. Puppeteer wait for lists coming up. The function you pass to evaluate is not a closure. – user5734311. log(result); // 123 Enable stealth mode (via puppeteer-extra-plugin-stealth) Randomize User-agent or Set a valid one (via random-useragent) Randomize Viewport size; Skip images/styles/fonts loading for better performance; Pass "WebDriver check" Pass "Chrome check" Pass "Notifications check" Pass "Plugins check" Pass "Languages check" Link to full code is here Importing a long JS function from a different file: let startTheShow = require('. exposeFunction() produce unhandled promise rejections; How to pass a function in Puppeteers . race doesn't cancel the waitForTimeout promise. You cannot pass a function directly into page. return value from puppeteer I had the same issue, Puppeteer was crashing a free-tier EC2 instance when I tried to pass ~20MB of data to evaluate(). 8. log works, but inside the Chrome console and not the Puppeteer one. (anonymous function) (puppeteer_evaluation_script:13:22)\n at puppeteer_evaluation_script:3:31 In the documentation's example, it is passing a string (which can be serialized). debug("Message") method. I am trying to convert a function that is used in puppeteer to puppeteerSharp and i am wondering how to do it. evaluate, I That anonymous function you pass to page. evaluate in puppeteer, in order to get the all gages of a gallery. selector. evaluate function and call resolve inside when your script is finished. Ask Question Asked 3 years, 5 months ago. evaluate, e. evaluate() 0. I'm using a nice logging library in node, which writes a log message with a simple logger. js and Puppeteer for the first time and can't find a way to output values from page. I can't figure out how to pass the logger object into page. waitForFunction( . type('input[type="password"]', loginData. Code within page. This applies to all instances of puppeteer functions operating within the context of browser. evaluate serialize a function and send it to the puppeeter browser. evaluate` - starts to await promise via the `Runtime. It is returning undefined - which according to the docs I think is for a good reason (non-serializable). – Passing Variables to Puppeteer's Evaluate Function. Which I believe is some sort of serialization and deserialization. evaluate() function - Puppeteer. evaluateHandle is that evaluateHandle page. $$('. When you use evaluate, the function you pass can return I wouldn't call resorting to evaluate a hack, since Puppeteer doesn't pretend to offer helpers for everything, but you're right that abusing console. 52. querySelector(selG); can't return anything. So it could potentially run 500 times and execute const listEl = document. evaluate? I am trying to use an XPath and an external variable in Puppeteer's evaluate function, but there is a problem: if I use the evaluate function with passing in the external variable then I can't pass in the XPath, if I remove the XPath everything is fine, but I need to do it with an XPath. Many people think eval is evil, maybe there is a better way, but at least it's a possible workaround. As a result, it doesn’t have access to variables defined in the parent scope. The evaluate function does not run when called. Hot Network Questions Puppeteer Pass variable in . But a single argument passed is not available to the pageFunction. Function argument of page. Is there something I am doing wrong? Evaluation failed: DOMException: Failed to execute 'querySelectorAll' on 'Element': '[object Promise]' is not a valid selector. evaluate(), but you can call another special method (page. evaluate and instead pass this entire "package" to page. Specifically, I've tried The Puppeteer Documentation for page. evaluate returns a Promise, the function will wait for the promise to resolve and return its value. Is it possible to pass a function to Puppeteer's page. evaluate() is executed in the document (browser) scope and has no access to the main script scope (including pSelector variable). To pass an argument to the function you provide to page. There are several ways to do it, but I use a wrapper called evaluate, which accepts additional parameters to pass to the function that must be evaluated on the webkit side. Evaluate is called from File A where pageFunction is Function and args is params that can be passed to that function. I obviously don't want to have a bunch of functions with the selectors hard coded I want to pass it in to the page evaluate. evaluate() Puppeteer evaluate function; allow to pass a parameterized funciton as a string to page. evaluate. js to do this. Learn how to use Puppeteer's evaluate function to pass objects and execute scripts in the browser context. log() calls:. exposeFunction but that seems to be for an anonymous function that is created inline. Puppeteer - variable not getting passed in the evaluate function. For each tr, there is position, title, URL. Puppeteer: pass variable in . Thankfully however, Puppeteer has a way Puppeteer - failed to pass variable into an evaluate function 1 Node Js Puppeteer value is not defined in the function (page. page. I am using the evaluate function to return links within a drop down in our application. Selector. It's executed in page context and page context doesn't know anything about test context. Usage. js environment to the browser context. evaluate() this should work as well. calls because they thought they had to. evaluate) Update for version 1. evaluate() function like this: const links = await page. evaluate() 1. Problem: The return value for page. My current implementation, which is based on Puppeteer, iterates on the csv file and stores such variable names in an array named as "variables". g. – Hi im learning puppeteer headless browser, but there is something that i dont understand 1) Pass the variable to the evaluate function as an argument. close(). To expose a function to the page from your Node. The workaround I found is to save the arguments to a file, pass the file path to the browser, and then fetch it. I want to run a function inside evaluate(), I'm passing it as an argument, but I'm getting 'func is not a function', what am I missing? Puppeteer version: 10. Conclusion Executing JavaScript within the page context while automating with Puppeteer is straightforward with the page. evaluate Whatever you get from await page. So how can I change my code to make this work ? – PepeW. evaluate() Functions. x and above - Jan 2020. 1 Puppeteer - How to evaluate XPath which returns text? 0 Puppeteer returning undefined (JS) using xPath. multiplePositionsPerJob is a function that I've referenced with require in the file. You can pass a string instead of a function Is there a way to "cache" a value in Puppeteer's browser-based functions? The callback passed to page. Any ElementHandles passed to evaluate (or have . Stack Overflow. evaluate() method with our expert guide. If you use page. To make function see vars from test context, you should pass them as a function argument. evaluate() will be run in the browser, not in the Node execution context. evaluate to extract any information necessary: pSelector is a variable that is defined in the Node. (see the docs for more information). js Skip to main content. evaluate((a, b) => { // you can use `a` and `b` here }, a, b); You can read more on arguments for the method in the docs here. js scope (main script scope). To return the data you have to use the return statement or use the short syntax (as explained below): console. return value from puppeteer page. When you call do_many_operations(elems[0]);, elems[0] is serialized (JSON. log. I want to pass the existing logger object that I I've already tried everything mentioned in Error: Evaluation Failed: ReferenceError: util is not defined and How to pass required module object to puppeteer page. To transfer any variables of main script scope to document (browser) scope, we need to add them as second, third, etc. Puppeteer's page. You switched accounts on another tab or window. and. If the function passed to page. I explored page. Func | string Steps to reproduce Tell us about your environment: Puppeteer version: 1. EvaluateFunctionAsync(@"async The issue is that # is a special character in URLs. How c I need to use a function inside page. mimg"), img => img. How to use Puppeteer’s page. map((index, element) => { i want to call for each tr ". any explanation would be appreciated. If you want to reuse code you can create functions on the browser side using evaluate: His await function serpDesc would need to be contained in an async function. Code: // First we register our listener. Evaluation failed: ReferenceError: multiplePositionsPerJob is not defined. click(). As you may have figured it out already, the reason why page. However, as soon as I build the source with pkg - page. js environment; you need to explicitly pass them as arguments. Puppeteer can't do this with nested ElementHandles, as of the time of writing. evaluate: You can pass a function that returns a Promise to the page. About; The solution that worked for me was to pass a string to evaluate rather than a function: Change: const dados = {name: 'foo', year: 1} await page. Modify it as below: getTextsForChildElements: async function (selector) { const data = await page. pageFunction. The anonymous function which is the first argument to the page. In the latest version args has been replaced with _args. The variables j and contactList do not exist in the context of the page. Share. evaluate(`async() => { return Promise. evaluate(): Learn how to use Puppeteer's evaluate function to pass objects and execute scripts in the browser context. waitForFunction() with puppeteer. 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. evaluate() returns. Note (my bold) "evaluated in the page context". log(await page. You need to return something from that anonymous function, and then call fs. Run Async method within puppeteer event. evaluate method. This is particularly useful for interacting with the DOM, performing calculations, or manipulating data directly within the browser environment. evaluate cannot directly reference variables from the Node. evaluate and elementHandle. exposeFunction capabilities. While learning and practicing with puppeteer I run into a problem what’s happening here is that I am passing i as an argument to the function. I need this variable to be used inside the browser's context. evaluate? 2 Puppeteer: How to evaluate an XPath with a Parameter. evaluate so I can use it in there. evaluate executes in page context and is separate from the puppeteer execution environment. evaluate() is isolated from the Node. evaluate(pageFunction[,args]). This occurs because How can I dynamically inject functions to evaluate using Puppeteer? [duplicate] (3 answers) Passing a function like that is no problem at all. await page. evaluateHandle() and you want to get the console. You can pass a string One glitch I ran into that was non-obvious to me: It looks like Promise. evaluate(), puppeteer sends function code to the browser as a string and browser compiles it and execute in the browser context, without access to the puppeteer context, so you need to transfer the argument number explicitly. Quote from the docs: Use the EvaluateFunctionAsync method in PuppeteerSharp package in your next Puppeteer-sharp project with LambdaTest Automation Testing Advisor. how to put a delay in this evaluate with puppeteer. The "main" function receiving the page and doing page. This is called the browser context. awaitPromise` if the return type of the evaluation is promise closes #118 You can only pass serializable data to the 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 I've got a little app i've written with node. selG is defined into the script you used to launch Puppeteer but the function you pass to page. evaluate; Functions bound with page. How are you sure? If you're verifying the form's presence by looking at the developer tools, that's no guarantee that the element wasn't added dynamically via JS after the page. evaluate puppeteer. var result = await page. I'm using puppeteer and node. I've run into a situation that I do not understand. evaluate not running console. Puppeteer Sharp strange behaviour. The function page. js context). 15. Variables in page. When trying to pass in a simple object into a async function that runs puppeteer, i get this error: (node:4000) UnhandledPromiseRejectionWarning: Error: Evaluation This function in serialized, and send to the headless browser, inside puppeteer. For this, I am using a puppeteer evaluation function, which works correctly while the file is in . Exposing is there for you if you want. In both examples I pass the "pageFunction" as parameter to both methods. stringify ()\n at window. Nodejs/Puppeteer - How to use page Puppeteer: pass variable in . You signed out in another tab or window. This method allows you to compute MD5 hashes directly within the page context, leveraging Puppeteer's page. The variable passed doesn't work. Pass a function inside page. I want to pass the result of that function into page. e. I'm abl Anything inside of page. I am scraping data from a webpage, pagination also works. Close Browser: Finally, close the browser with browser. dgControl_list>li img. Puppeteer returns undefined for page. you're not passing in a function but the result of the function, which is a boolean. I was wondering if there is a way to cache listEl So to make your code passing an argument to be written in an input element selector, your code should be like this. 0. Alternatively, you can specify the selector type using a prefix. $ call runs. const title = await page . Returns: Promise<HandleFor<Awaited<ReturnType<Func>>>> Remarks . evaluate() function. The primary difference between page. evaluateHandle returns a Promise, the function will wait for the promise to resolve and return its value. querySelectorAll(selector)) I am using puppeteer and the script works fine when executing directly with node. If you want a "tricky" solution you cant try exposeFunction but usually is not a good way. $(". To achieve this, it's essential to understand the correct method of passing variables into the page. This handle can be a JSHandle or an ElementHandle, depending on the type of object returned by the function. Here's the stripped down version of the code : let currentPost = 1; await page. Hot Network Questions Alexander's dictum If you're using a transpiler like babel you might need to pass the function as a string to page. So when you are using page. password, {delay: 10}); // Types faster, just like robot 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 There is a serialization process when you call a function registered with exposeFunction. evaluate and I don't understand why. This issue is specifically with elementHandle. Error: Evaluation Failed: ReferenceError: util is not defined. Below is the syntax for using the evaluate function: You pass arguments to the evaluate method like this: page. Master puppeteer page. log() text from the browser context back to node, use the following code and make sure to set the listener before any console. 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 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 I’m trying check if elements are available on a page from within a function, if the element is on the page, good, continue with the code, if not, Puppeteer: use function inside page. So imports won't work in this context, at least not how you're attempting it. – Kevin. 1. This is the function signature of puppeteer's page. . 1 Puppeteer: How to evaluate xpath with document. In simpler terms, running page. I have a function called getContent() which I need to pass parameters to from a foreach loop in evaluate() but if I try to pass the function using that syntax ex: page. Works quite fast compared to what Puppeteer does. How can I evaluate a page retrieved by an url form a parent page in puppeteer`s evaluate function. When using Puppeteer to evaluate a page, it's often necessary to pass variables into the evaluation function for use within the page's context. If this still does not solve your problem, then you probably want to share all context at same scope. If you console, it will say JShandle or ElementHandle depending on the type. Passing Puppeteer page as params in a function is not working as expected. evaluate with puppeteer. I'm trying to require a function from a different file into my evaluate callback, however the function never fires and causes evaluate to fail. 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 You can build a function where the first argument is always the JSHandle but the rest of them are values you can pass to the evaluate function. 0 Platform / OS version: macOS Mojave / 10. I'll add an answer to explain in detail. Using page. function waitFor(delay) { return new Promise(resolve => setTimeout How do pass arguments to a page. Wherever he has his await page. Skip to PuppeteerSharp passing parmaters to evaluateFunctionAsync() I've seen a good number of Puppeteer scripts in a state of confusion as the author tried to translate their working console code to page. 0 What is the expected result? to run What happens instead? I get the er 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 I have a csv file that stores the name of JS variables that I would like to read (evaluate) once going to a site. It can be done with a little trickery, because page. Puppeteer page. evaluate(() => { return Array. evaluate() is akin to opening Dev tools and writing set_calendar_date('1') there directly. evaluate also can accept a string. In Puppeteer, the page. How to use url module in puppeteer page. While checking the code for elementHandle. But what is a page function in puppeteer? Edit: I should add that the following passage is given in the documentation but I don't understand what it means: pageFunction <function|string> Function to be evaluated in the page context. Any code that you write inside of page. I just get this error: I found something like that works for variable, but now i need to pass a function also. I have a table with tr. evaluate is essentially run inside of Chrome's DevTools console, or in the same context you'd be in if you were to do so. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, As per documentation page. You can pass in parameters to the evaluate function to get around this. Execute puppeteer code within a javascript function. Question about Puppeteer xpath element evaluation. It states: pageFunction <function|string> Function to be evaluated in the page context. js environment, which means it does not have access to variables from your Node. 2. evaluateHandle method in Puppeteer allows you to execute a function within the context of the page and returns a handle to the result. evaluate, The function setValue receives a value and returns a function. If you have errors like Error: Evaluation failed: TypeError: Cannot read property 'click' of null probably the element you wanted to click isn't on I would prefer to not have to redefine each of them within page. element") const element2=await page. We can pass a function as an argument to the evaluate function that will be executed within the page's context. const puppeteer=require("puppeteer"); (async Puppeteer evaluate function on load to show alert. Puppeteer: How to evaluate an XPath with a context node? 1. We currently rely on a generic notion of Serializable objects, and it's quite easy to predict what will safely cross the boundary and whatnot. evaluate method to run JavaScript code in the context of the page? ('puppeteer'); async function runCodeInPage() { const browser = await puppeteer. I do not understand why this is happening. resolve(42); }`); (puppeteer will call . evaluate() function is a versatile tool for executing JavaScript within a page's execution context. I'm getting multiple errors with page. evaluate((evalVar) => { console. Here’s how you can pass the I am trying to pass my custom object to page. user, {delay: 100}); // Types slower, like a user await page. In Pupeteer, I'd like to pass an arbitrary number of ElementHandle to the method evaluate in an array: const element1=await page. js environment, you can use the page. evaluate(pageFunction, args); So u need to so something like this: Puppeteer's evaluate function allows you to execute JavaScript code within the context of the page. The function in evaluate will be evaluated in the page context Or write your async delay function similar to page. Promising an async function. evaluate function as argument. evaluae((getContent()) => it Serializable|JSHandle> Arguments to pass to pageFunction returns: < Promise < Serializable >> Promise which resolves to the return value of pageFunction This method runs Array. evaluate (() => document . a. Pass a function to evaluate() in puppeteer. evaluate of puppeter script. Edit: typo! So, I have a function that returning page that needed by next function: async function browser(){ const browser = await puppeteer. exposeFunction. evaluate() you're switching the context from node puppeteer to browser, so you have to use JS native functions like click: document. Puppeteer uses DevTools Protocol, which requires you to pass a stringified function. evaluate((selector) => Also, note that the function you pass to page. This function lets you run any JS function in the page context. I'm using Puppeteer. Puppeteer has to perform the translation under the hood. However, passing variables into this function can be tricky. evaluate? 2. Puppeteer - How to evaluate XPath which returns text? 1. I'd suggest taking look at the docs and the architecture. When you use evaluate, the function you pass can return There is a similar problem if you try to pass a function. querySelector(selector). I think you'll find the answer here: How can I Puppeteer's evaluate function allows you to execute JavaScript code within the context of the page. Modified 1 year, 9 months ago. Commented May 15, The page context that Puppeteer spawns (in its virtual browser) is not the same as the Node context that you write the implementation code in. Simple easy way probably obvious to some but for those like me, I To execute JavaScript code on your puppeteer instance, you can use the provided evaluate method. According to the Puppeteer documentation, it says:. evaluate resolves to undefined. querySelector("#list") 500 times. evaluate() method? How can I dynamically inject functions to evaluate using How to use imported function inside page. evaluate() method? Why can't I access 'window' in an exposeFunction() function The page. evaluateHandle. from(document. evaluate should accept the arguments which you are passing. You would use it like this: Hi I am working on a web scraping script, and I have a function that currently returns to me a string. evaluate() Share. I didn't see an obvious/simple way to fix this The evaluate function in Puppeteer allows us to run JavaScript code within the context of a web 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 how do I call a function passing the page object outside async method in puppeteer. These are parameters that you can pass from the Node. evaluate(), you should include it as an additional parameter. evaluate for repository readability I think for smaller projects the simplest and best option is to just re-declare the objects/functions in the puppeteer context. launch(); By passing arguments to page. I want to implement a functionality where if a certain value is found on page it should play a music. How to pass a function in Puppeteers . js'); And then trying to use that function on the page. evaluate() 9. 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. To display the logs of the Chrome context inside the Puppeteer console, you can set dumpio to true in the arguments when launching a browser using Puppeteer: To parse any data from a page you would rather wait for it to load completely and then use page. evaluate despite being resolved on devtools. puppeteer evaluate functions not accepting JSHandles or ElementHandles as variables. evaluate(async => { await new Promise You can call EvaluateFunctionAsync and pass that function as string. On the node side, that object won't have a getBoundingClientRect function. I've seen people stringifying the function to pass it to puppeteer to make it work, so in your case I'd do this using eval. @MattSergejRinc it doesn't work like that - the function that you pass in is executed by the browser that Puppeteer is running, not by your script, so it doesn't have access to variables that the evaluate function is closed over. It provides a powerful way to interact with the page's DOM and extract information. Reload to refresh your session. exposeFunction), which expose your function as a global function (also available in as an attribute of your page window object), so you can call it when you are inside page. evaluate() method. So, here is how I solve it. the reason behind this is that whatever is inside page. read the passed data const lastUpdate = await page. evaluate and page. wait for setTImeout in page. Code Sample. The function you provide as the first argument will be In Puppeteer, when you're passing a variable into the page. evaluate takes pageFunction and a list of arguments which would be passed to the pagFunction. evaluate() or page. The only difference between page. js context, including any Evaluation failed: TypeError: Converting circular structure to JSON\n at JSON. In the provided Puppeteer script, attempts to pass the variable evalVar into the evaluation function links are unsuccessful, resulting in the variable being undefined when accessed within the function. using arrow function into the return block of page. evaluate() must be serializable. You can pass a string instead of a function (although functions are recommended as they are easier to page. 5. 2. 15. evaluate() function allows developers to execute JavaScript within the browser context. As moment is a function and a function cannot be serialized you cannot use it that easy. Here is a working snippet, don't hesitate to pass {headless: false} to puppeteer. 14 URLs (if applicable): Node. CSS selectors can be passed as-is and a Puppeteer-specific selector syntax allows quering by text, a11y role and name, and xpath and combining these queries across shadow roots. Because of that, if you want to use an outside variable (a selector, for example) inside the function, you have to pass that variable as an argument to evaluate: In order to make sourceURL comments possible, this patch: - removes wrapping of the client function into `Promise. Return Types. evaluate((selector) => { const tds = Array. evaluate to the outer scope. waitFor in puppeteer. What you need to do is to create a Promise yourself and tell it to resolve once you have the array ready. stringify) and passed to your function in Node. if you look at the example I showed of casperjs, you can see there is this line where you are basically executing a function on the Using eval() or Function() constructor inside the evaluated function and transfer the function code as a string (difficult for code writing, linting etc. evaluate() method? The code inside page. evaluate returns a non-Serializable value, then page. But it doesn't work. evaluate fails is because the function is evaluated in a different context and the current scope (where createHdpiCanvas is available outside of the function) is lost. the form exists in the page and i am sure. Right not, it it not taking any arguments. The code inside page. puppeteer evaluate functional with callback. launch() if you want to see it working with your I'm working with Node. querySelectorAll("ul. alljobs is an array I'm trying to push objects to. querySelectorAll(selector)) within the page and passes it as the first argument to pageFunction . evaluate? 21. Trying to execute a for loop within the page. waitForFunction functions start failing wi I've had that exact problem. 5. What you are looking for is the page. How can I pass a string in and have that string be available inside of my page. In function . "doesn't work" is a useless problem description; please clarify how the code fails for you. js and puppeteer. To access the variables from in-page context in puppeteer, you need to return the variables. evaluate(() => new Promise(resolve => { // do all kind of asynchronous actions resolve(123); })); console. Tried all the different ways (saving it as a function/function expression/anonymous function, with without async), nothing works. How do you feel about a PR? @Vandivier I'd rather not. Learn how to set up and run automated tests with code examples of EvaluateFunctionAsync method from our library. Pass the elementHandle to the page. evaluate? 0. ptz wge fhae wkro zxcmxh zxknsz vehho qmdp bvvn wtmwwb