Puppeteer pass function to evaluate. This makes it hard make the scraping code generic.

Puppeteer pass function to evaluate 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. You should pass arguments after evaluate arrow function. Puppeteer - failed to pass variable into an evaluate function. 0 Fail to use page instance in a function using puppeteer. x and above - Jan 2020. evaluate, I Contribute to puppeteer/puppeteer development by creating an account on GitHub. I just get this error: This function lets you run any JS function in the page context. evaluate is run in the browser context, so the console. It I found something like that works for variable, but now i need to pass a function also. Evaluation failed: ReferenceError: multiplePositionsPerJob is not defined. await page. Hot Network Questions Update for version 1. Works quite fast compared to what Puppeteer does. map((el) => { How to Pass Variables into an Evaluate Function in Puppeteer. evaluate? 0. There is a serialization process when you call a function registered with exposeFunction. exposeFunction() produce unhandled promise rejections; How to pass a function in Puppeteers . evaluate((selector) => { const tds = Array. Evaluate is called from File A As per documentation page. $ with a follow up function. Try Teams for free Explore Teams Puppeteer evaluate function. another-element") awai Puppeteer: use function inside page. Bug expectation The documentation and certainly many Stack Overflow answers seem to imply that Page. evaluate? 2. 1. G. evaluate() or page. evaluate puppeteer. querySelectorAll(selector)) I am using puppeteer and the script works fine when executing directly with node. $$('. I pass in an variable array that I would like to use to retrieve links from these sections in a drop down. When you call do_many_operations(elems[0]);, elems[0] is serialized (JSON. 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() runs in the context of the web page puppeteer is running in, so of course it doesn't know what fs is. 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. Puppeteer's page. These are parameters that you can pass from the Node. Run Async method within puppeteer event. evaluate() Puppeteer evaluate function; allow to pass a parameterized funciton as a string to page. 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. evaluate() method? How can I dynamically inject functions to evaluate using How to use imported function inside page. what’s happening here is that I am passing i as an argument to the function. This handle can be a JSHandle or an ElementHandle, depending on the type of object returned by the function. evaluate takes pageFunction and a list of arguments which would be passed to the pagFunction. Puppeteer page. puppeteer find some data and then I use these functions to test if the data has a certain date, null values, etc. evaluate(), but when I run the script it throws a following error: Error: Evaluation failed: TypeError: Cannot read property 'p1' of undefined. 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 Ask questions, find answers and collaborate at work with Stack Overflow for Teams. How c This code can pass a variable inside evaluate(). tweet') is an array of elementHandle. querySelector('input[name="q"]'). How to pass array and function to Page. appendFileSync with that:. evaluate() method with our expert guide. js environment to the browser context. exposeFunction("mapDateValue", (value) => { return According to puppeteer docs here, $$ Does not return a nodelist, Pass the elementHandle to the page. 3 Puppeteer - failed to pass variable into an evaluate function. evaluate() function - Puppeteer. Take a a look at the Puppeteer documentation for page. title ); This returns the document title from the puppeteer instance In Puppeteer, page. E. On the continuity a function given by evaluating compact subsets of I am new to puppeteersharp and puppeteer in general. How can I pass an existing object into Puppeteer's page. Function argument of page. 2 I had the same issue, Puppeteer was crashing a free-tier EC2 instance when I tried to pass ~20MB of data to evaluate(). 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. It states: pageFunction <function|string> Function to be evaluated in the page context. g. 7. Many people think eval is evil, maybe there is a better way, but at least it's a possible workaround. evaluate() is akin to opening Dev tools and writing set_calendar_date('1') there directly. Return from async/await function inside async/await function (Puppeteer) 2. evaluate Puppeteer (Javascript) 0. Explore Teams In Puppeteer you can evaluate async functions: await 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. evaluate() method? When trying to pass in a simple object into a async function that runs puppeteer, i get this error: (node:4000) UnhandledPromiseRejectionWarning: Error: Evaluation How to pass a function in Puppeteers . Question about Puppeteer xpath element evaluation. open(url, function() { var foo = 42; page. 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. Commented May 15, 2019 at 23:09. In simpler terms, running page. log. Reload to refresh your session. debug("Message") method. log() text from the browser context back to node, use the following code and make sure to set the listener before any console. So, I have a function that returning page that needed by next function:. To transfer any variables of main script scope to document (browser) scope, we need to add them as second, third, etc. Here’s how you can pass the How to pass a function in Puppeteers . Explore Teams Does the code run properly without puppeteer? I mean, can you manually execute the code first on your browser and see what happens? and, is myFunction a promise? page. waitForFunction functions start failing wi My problem is that the code I pass to the webkit page is sandboxed, and so has no access to the variables of my main phantom script. evaluate and I don't understand why. I want to implement a functionality where if a certain value is found on page it should play a music. 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. js environment, which means it does not have access to variables from your Node. Conclusion Executing JavaScript within the page 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). I do not understand why this is happening. Try this: how do I call a function passing the page object outside async method in puppeteer. If you want a "tricky" solution you cant try exposeFunction but usually is not a good way. Code: // First we Puppeteer: use function inside page. evaluate isn't a part of you code, and you can't call a function of your code from it. However, passing First, it is important to understand that there are two main environments: Node. As a result, it 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. Yeah the data is in the puppeteer browser. If the function passed to page. I am trying to pass my custom object to page. evaluate(pageFunction, Pass a function to evaluate() in puppeteer. element") const element2=await page. value = keyword; }, keyword); And this The anonymous function which is the first argument to the page. I'm using Puppeteer. js scope (main script scope). evaluate() 2. 1 Node Js Puppeteer value is not defined in the function (page. To achieve this, it's essential to understand the correct method of passing variables into the page. evaluate(): Executing JavaScript within the page context while automating with Puppeteer is straightforward with the page. Puppeteer: use function inside page. It provides a powerful way to interact with the page's DOM and extract information. The issue is that # is a special character in URLs. Improve this answer. It seems, exposed functions, as well as evaluated functions, can only use serializable arguments, so functions cannot be transferred between Node. evaluate cannot directly reference variables from the Node. It can be tested on try-puppeteer, just copy and paste my code and remove the require statement. 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. Error: Evaluation Failed: ReferenceError: util is not defined. This issue is specifically with elementHandle. This makes it hard make the scraping code generic. js script scope. But to your point, I could break things up and pass data out of one evaluate, process that data with the url module, and then pass the processed data back into another evaluate. exposeFunction but that seems to be for an anonymous function that is created inline. e. 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: I've run into a situation that I do not understand. — this can be mitigated a bit by So, here is how I solve it. In puppeteer page. You need to return something from that anonymous function, and then call fs. One glitch I ran into that was non-obvious to me: It looks like Promise. The evaluate function does not run when called. Inside the second function I'm trying to console log the value of value but I get . You cannot pass a function directly into page. Puppeteer - variable not getting passed in the evaluate function. from(document. You can pass a string instead of a function (although functions are recommended as they are easier to debug and use with This applies to all instances of puppeteer functions operating within the context of browser. evaluateHandle method in Puppeteer allows you to execute a function within the context of the page and returns a handle to the result. puppeteer evaluate functions not accepting JSHandles or ElementHandles as variables. The function you provide as the first argument will be serialized and executed in the context of the page. The primary difference between page. Puppeteer evaluate function. using arrow function into the return block of page. Puppeteer: log HTML DOM object in evaluate() 0. evaluate serialize a function and send it to the puppeeter browser. page. Return Types. Maybe you can try a wrapper and a dictionary of functions, so you can transfer function names as strings: How to pass a function in Puppeteers . If the returned value This function in serialized, and send to the headless browser, inside puppeteer. Here's the stripped down version of the code : let currentPost = 1; await page. evaluate(pageFunction[,args]). 3. a. evaluate() 1. You switched accounts on another tab or window. As you may have figured it out already, the reason why page. evaluate and elementHandle. evaluate() for web automation and testing. So if myFunction is not a promise, you are expecting the wrong return. I would expect the provided example to alert "Hello World". evaluate() method. stringify) and passed to your function in Node. evaluate() 9. This can be useful for interacting with the DOM (Document Object Model) or extracting information If you want access to the window or document objects—to scrape some information from the page, for example—you can use the page. ; returns: <Promise> The method adds a function called name on the page's window 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. launch({args: ['--no-sandbox Serializable|JSHandle> Arguments to pass to pageFunction; returns: <Promise<Serializable>> Promise which resolves to the return value of pageFunction; This method runs Array. pass multiple parameters into page. 15. Share. – You pass arguments to the evaluate method like this: page. $(". Is it possible to pass a function to Puppeteer's page. 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 . Also, note that the function you pass to page. Simple easy way probably obvious to some but for those like me, I hope it To parse any data from a page you would rather wait for it to load completely and then use page. evaluate was once capable of taking parameters to use inside the browser. How would I go about this function? I'm getting multiple errors with page. Error: Evaluation failed: ReferenceError: value is not defined My code bellow. Below is the syntax for using the evaluate function: That anonymous function you pass to page. How to pass page as an argument in the function parameter of page. evaluate() is a method that allows you to execute JavaScript code in the context of the page. log() calls:. evaluate() when you are seeking to interact with the page There is a similar problem if you try to pass a function. I am using the evaluate function to return links within a drop down in our application. $$eval function? I have the below code but does not work. I want to pass the result of that function into page. log('hello') in your page function, it will log it to the console in the browser. js (Puppeteer) Environment; Page DOM Environment; You should use page. multiplePositionsPerJob is a function that I've referenced with require in the file. evaluate(), you should include it as an additional parameter. Puppeteer - How to evaluate XPath which returns text? 1. To achieve this, it's essential to Using eval() or Function() constructor inside the evaluated function and transfer the function code as a string (difficult for code writing, linting etc. In the latest version args has been replaced with _args. evaluate(() => { return document. log(foo); }); } The function page. evaluate() function, you need to ensure that the variable is correctly referenced within the function. 15. 2. Here is the puppeteer function(th pSelector is a variable that is defined in the Node. EvaluateFunctionAsync(@"async => { // await some promise }"); In Puppeteer, when you're passing a variable into the page. Puppeteer: How to evaluate xpath with document. evaluate(), but you can call another special method (page. evaluate in Puppeteer with Jest? 2. evaluate should accept the arguments which you are passing. vid'). To pass an argument to the function you provide to page. launch() if you want to see it working with your own eyes. How can I pass a string in and have that string be available inside of my page. You signed in with another tab or window. evaluate(async => { // await some promise }); Is there an equivalent in PuppeteerSharp? Using EvaluateFunctionAsync, the task completes before the promise resolves: await page. querySelectorAll('a. Usage. Here is a pretty simple example, and maybe somebody can see if i'm just doing something stupid here. js environment; you need to explicitly pass them as arguments. evaluate() 0. myclass. evaluate can't find text. evaluate (() => document . However, as soon as I build the source with pkg - page. Trying to execute a for loop within the page. 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. If you want to reuse code you can create functions on the browser side using evaluate: How to pass a function in Puppeteers . const texts = await page. evaluate will just evaluate something and if it's a promise it'll wait for the promise to return. 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. So I am needing these functions to test conditions to determine what data should be 'pulled' from the browser. I use exposeFunction and I need to send the full Element to my function. like this page. So how can I change my code to make this work ? wait for setTImeout in page. This powerful feature allows you to directly manipulate the DOM, interact with page scripts, Learn how to use Puppeteer's evaluate function to pass objects and execute scripts in the browser context. Ins With page. evaluate the value of a variable inside page. evaluate() function. Commented Aug 27, 2020 at 21:20. But a single argument passed is not available to the pageFunction. Any ElementHandles passed to evaluate (or have . async function browser(){ const browser = await puppeteer. I explored page. Puppeteer: How to evaluate an XPath with a context node? 1. The function setValue receives a value and returns a function. Related questions. Promising an async function. The Puppeteer Documentation for page. 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. Master puppeteer page. 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. I didn't see an obvious/simple way to fix this 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. How do I pass a function to Puppeteer page. race doesn't cancel the waitForTimeout promise. How to await an async function evaluation in PuppeteerSharp. Right not, it it not taking any arguments. Simple easy way probably obvious to some but for those like me, I Variables in page. evaluate; Functions bound with page. I would just prefer to be able to do it all at once inside one evaluate. evaluate((keyword) => { document. evaluate? Pass a function to evaluate() in puppeteer. evaluate(function() { // this code has no access to foo console. Explore examples to leverage page. evaluate with puppeteer. evaluate method: The function you pass to evaluate is not a closure. 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. I want to pass the existing logger object that I You signed in with another tab or window. evaluateHandle is that evaluateHandle I'm using a nice logging library in node, which writes a log message with a simple logger. While checking the code for elementHandle. 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. 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. Puppeteer Sharp strange behaviour. – user5734311. In puppeteer how to wait for DOM element to load and then click. Execute puppeteer code within a javascript function. This in turn determines if/how page navigation should occur. On the node side, that object won't have a getBoundingClientRect function. So when you are using page. js and puppeteer. Ask questions, find answers and collaborate at work with Stack Overflow for Teams. Puppeteer evaluate returns undefined for an array of DOM nodes. Thankfully however, Puppeteer has a way Puppeteer: pass variable in . It is returning undefined - which according to the docs I think is for a good reason (non-serializable). The variables j and contactList do not exist in the context of the page. Puppeteer wait for lists coming up. Puppeteer's evaluate function allows you to execute JavaScript To execute JavaScript code on your puppeteer instance, you can use the provided evaluate method. evaluate() what’s happening here is that I am passing i as an argument to the function. . 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) The evaluate function in Puppeteer allows us to run JavaScript code within the context of a web page. evaluate() is isolated from the Node. alljobs is an array I'm trying to push objects to. 5. and. js and browser contexts as parameters. evaluate returns a Promise, the function will wait for the promise to resolve and return its value. "doesn't work" is a useless problem description; please clarify how the code fails for you. exposeFunction() states:. I have a simple example: Is it possible to pass a function to Puppeteer's page. Can I use puppeteer inside chrome extension. Whatever you get from await page. – Kevin. const title = await page . you're not passing in a function but the result of the function, which is a boolean. evaluate(pageFunction, args); So u need to so something like this: page. evaluateHandle() and you want to get the console. 0. It signals to the web browser a string called a "fragment" that targets an anchor on a web page. Note (my bold) "evaluated in the page context". evaluate method to run JavaScript code in the context of the page? The page. evaluate () function is a versatile tool for executing JavaScript within a page's execution context. evaluate so I can use it in there. The workaround I found is to save the arguments to a file, pass the file path to the browser, and then fetch it. Here is a working snippet, don't hesitate to pass {headless: false} to puppeteer. evaluae((getContent()) => it A page function is a function that Puppeteer (through NodeJS) turns into a string, sends to the browser, and then runs inside the Chromium instance. evaluate () Functions. When you use evaluate, the function you pass can return values. Which I believe is some sort of serialization and deserialization. Different behavior for page. evaluate. 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? Center table headers over certain columns Are there actual correct representations of I've got a little app i've written with node. This is particularly useful for interacting with the DOM, performing calculations, or manipulating data directly within the browser environment. evaluate and page. 4. I need this variable to be used inside the browser's context. Modify it as below: getTextsForChildElements: async function (selector) { const data = await page. Puppeteer can't do this with nested ElementHandles, as of the time of writing. The code inside page. In Pupeteer, I'd like to pass an arbitrary number of ElementHandle to the method evaluate in an array: const element1=await page. evaluate to extract any information necessary: Puppeteer's evaluate function allows you to execute JavaScript code within the context of the page. Puppeteer - Running a function inside a frame. evaluate() method (5 answers) Passing a function like that is no problem at all. evaluate of puppeter script. How to use url module in puppeteer page. The variable passed doesn't work. I can't figure out how to pass the logger object into page. I’m not familiar with pupeteer at all but by looking at the documentation for that function, there may be something you can try. querySelectorAll(selector)) within the page and passes it as the first argument to pageFunction. I am trying to convert a function that is used in puppeteer to puppeteerSharp and i am wondering how to do it. Hi I am working on a web scraping script, and I have a function that currently returns to me a string. How can I pass variable into an evaluate function that evaluates an async 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 I need to use a function inside page. evaluate not running console. Getting different results when using Puppeteer page. You signed out in another tab or window. Puppeteer has to perform the translation under the hood. If you use console. So, with that encoding, your URL parameter would be selector=%23hplogo. In fact this is the method signature: page. evaluate() is executed in the document (browser) scope and has no access to the main script scope (including pSelector variable). evaluate) 0 Puppeteer Pass variable in . If you post the predicted code i can suggest you a better way. ReferenceError: alljobs is not defined. log works, but inside the Chrome console and not the Puppeteer one. How to execute a js function on the page while automating in puppeteer? 5. Using puppeteer to test chrome extension. evaluateHandle. Hot Network Questions How to use Puppeteer’s page. We can pass a function as an argument to the evaluate function that will be executed within the page's context. zqf bhzo aidti llxd mrqhemf pqyy rfnnwjh wblnjr jhrcds jml