How to use EvaluateFunctionAsync method of PuppeteerSharp.Page class
Best Puppeteer-sharp code snippet using PuppeteerSharp.Page.EvaluateFunctionAsync
BaseScraper.cs
Source:BaseScraper.cs 
...92 }93 public virtual async Task<double> GetCurrentScrollHeight(string selector)94 {95 var chSelectorFunc = ScraperConstants.FUNC_SELECT_SIMPLE.Replace("{{SPECIAL}}", ".scrollHeight");96 return await CurrentPage.EvaluateFunctionAsync<double>(chSelectorFunc, selector);97 }98 public virtual async Task<double> GetCurrentScroll(string selector, bool addClientHeight = true)99 {100 var chSelectorFunc = ScraperConstants.FUNC_SELECT_SIMPLE.Replace("{{SPECIAL}}", ".scrollTop");101 var scrollTop = await CurrentPage.EvaluateFunctionAsync<double>(chSelectorFunc, selector);102 if (addClientHeight)103 {104 var clHeightFunc = ScraperConstants.FUNC_SELECT_SIMPLE.Replace("{{SPECIAL}}", ".clientHeight");105 var clientHeight = await CurrentPage.EvaluateFunctionAsync<double>(clHeightFunc, selector);106 scrollTop += clientHeight;107 }108 return scrollTop;109 }110 public virtual async Task ScrollTo(string selector, int toHeight, bool aproximate = true, bool useWindow = false)111 {112 var newHeight = toHeight;113 if (aproximate)114 newHeight -= 100;115 var scrollFuncCall = ".scrollTo(0, " + newHeight + ")";116 var scrollBottom = (useWindow ? ScraperConstants.WINDOW_FUNCTION : ScraperConstants.FUNC_SELECT_SIMPLE).Replace("{{SPECIAL}}", scrollFuncCall);117 await CurrentPage.EvaluateFunctionAsync(scrollBottom, selector);118 }119 public virtual async Task CloseAnnoyingElements()120 {121 var appSettings = SettingsManager.Settings;122 if (appSettings.ANNOYING_ELEMENTS == null || appSettings.ANNOYING_ELEMENTS.Length == 0)123 return;124 await this.CloseAnnoyingElements(appSettings.ANNOYING_ELEMENTS);125 }126 public virtual async Task CloseAnnoyingElements(string[] selectors)127 {128 var stillSearching = true;129 while (stillSearching)130 {131 stillSearching = false;...
Program.cs
Source:Program.cs
...62 var jscode = @"() => {63 const selectors = Array.from(document.querySelectorAll(`div.du4w35lb.k4urcfbm.l9j0dhe7.sjgh65i0`)); 64 return selectors.map( t=> {return {content: t.innerHTML}});65 }";66 var results = await page.EvaluateFunctionAsync<Content[]>(jscode);67 List<Data> authorNamesAndText = new List<Data>();68 foreach (var result in results)69 {70 Data data = new Data();71 await page.SetContentAsync(result.content);72 Thread.Sleep(500);73 string content = "", content2 = "";74 var elementHandle = await page.QuerySelectorAsync("span.d2edcug0.hpfvmrgz.qv66sw1b.c1et5uql.lr9zc1uh.a8c37x1j.keod5gw0.nxhoafnm.aigsh9s9.d3f4x2em.fe6kdd0r.mau55g9w.c8b282yb.iv3no6db.jq4qci2q.a3bd9o3v.knj5qynh.m9osqain.hzawbc8m");75 if (elementHandle != null)76 {77 try78 {79 content = await elementHandle.QuerySelectorAsync("span").EvaluateFunctionAsync<string>("node => node.innerText");80 }81 catch (Exception e1)82 {83 Console.WriteLine("error in getting content: " + e1.Message);84 }85 }86 if (content != "")87 {88 Thread.Sleep(500);89 try90 {91 content2 = await page.QuerySelectorAsync("div.kvgmc6g5.cxmmr5t8.oygrvhab.hcukyx3x.c1et5uql.ii04i59q").EvaluateFunctionAsync<string>("node => node.innerText");92 }93 catch (Exception e2)94 {95 Console.WriteLine("error in getting content: " + e2.Message);96 }97 data.author = content;98 data.posttext = content2;99 authorNamesAndText.Add(data);100 }101 }102 //print author and post list103 foreach (Data ap in authorNamesAndText)104 {105 Console.WriteLine("Author: " + ap.author);...
SaveWebPage.xaml.cs
Source:SaveWebPage.xaml.cs
...101 PuppeteerSharp.PdfOptions pdfOptions = new PuppeteerSharp.PdfOptions();102 pdfOptions.DisplayHeaderFooter = false; //æ¯å¦æ¾ç¤ºé¡µç页è103 pdfOptions.FooterTemplate = ""; //页èææ¬104105 var width = await page.EvaluateFunctionAsync<int>("function getWidth(){return document.body.scrollWidth}");106 var height = await page.EvaluateFunctionAsync<int>("function getHeight(){return document.body.scrollHeight}");107108 pdfOptions.Width = $"{width}px";109 pdfOptions.Height = $"{height}px";110111 pdfOptions.HeaderTemplate = ""; //页çææ¬112 pdfOptions.Landscape = false; //çº¸å¼ æ¹å false-åç´ true-æ°´å¹³113 pdfOptions.MarginOptions = new PuppeteerSharp.Media.MarginOptions() { Bottom = "0px", Left = "0px", Right = "0px", Top = "0px" }; //çº¸å¼ è¾¹è·ï¼éè¦è®¾ç½®å¸¦åä½çå¼ï¼é»è®¤å¼æ¯None114 pdfOptions.Scale = 1m; //PDF缩æ¾ï¼ä»0-1115 pdfOptions.PrintBackground = true;116117 var fileName = Environment.CurrentDirectory + $"\\download\\{await page.GetTitleAsync()}.pdf";118119 if (System.IO.File.Exists(fileName))120 {
...
Get-ScraperMobileVikings.cs
Source:Get-ScraperMobileVikings.cs
...65 decimal credits;66 try {67 var creditField = await page.WaitForSelectorAsync(68 "body > div:nth-child(1) > div:nth-child(3) > div > div > main > div > section > div > section > section.MvSection.balanceItemSection > div > div > div:nth-child(2) > strong");69 var creditText = await creditField.EvaluateFunctionAsync<string>("e => e.innerText");70 var creditMatch = Regex.Match(creditText, @"^[^\d]*(\d+)[,\.](\d+)$");71 if (creditMatch.Success) {72 creditText = creditMatch.Groups[1].Value + CultureInfo.InvariantCulture.NumberFormat.NumberDecimalSeparator + (creditMatch.Groups[2].Value ?? "0");73 credits = decimal.Parse(creditText, CultureInfo.InvariantCulture.NumberFormat);74 } else {75 throw new Exception($"Credits not found ({creditText})");76 }77 } catch (PuppeteerSharp.WaitTaskTimeoutException) {78 var creditField = await page.WaitForSelectorAsync(79 "body > div:nth-child(1) > div:nth-child(3) > div > div > main > div > section > div > section > section");80 var creditText = await creditField.EvaluateFunctionAsync<string>("e => e.innerText");81 if (creditText.Contains("Geen\nbelwaarde"))82 credits = 0m;83 else84 throw new Exception($"Credits not found (No credits left?)");85 }8687 // Get points88 System.Threading.Thread.Sleep(3000);89 decimal? points = null;90 if (!DontIncludePoints)91 {92 await page.GoToAsync("https://mobilevikings.be/en/my-viking/viking-points");93 Match pointMatch = null;94 string pointText = "";95 for (int i = 0; i < 10 && (pointMatch == null || !pointMatch.Success); i++)96 {97 System.Threading.Thread.Sleep(1000);98 var pointField = await page.WaitForSelectorAsync(99 "body > div:nth-child(1) > div:nth-child(3) > div > div > main > div > section.vikingPointsView__header.vikingPointsViewHeader > div.vikingPointsViewHeader__details.vikingPointsViewHeaderItem.available > div");100 pointText = await pointField.EvaluateFunctionAsync<string>("e => e.innerText");101 pointMatch = Regex.Match(pointText, @"^[^\d]*(\d+)[,\.](\d+)$");102 }103 if (pointMatch.Success) {104 pointText = pointMatch.Groups[1].Value + CultureInfo.InvariantCulture.NumberFormat.NumberDecimalSeparator + (pointMatch.Groups[2].Value ?? "0");105 points = decimal.Parse(pointText, CultureInfo.InvariantCulture.NumberFormat);106 } else {107 throw new Exception($"Points not found ({pointText})");108 }109 }110111 // Bundle112 return new MobileVikings { 113 Credits = credits,114 Points = points
...
AvitoPostParser.cs
Source:AvitoPostParser.cs
...43 };44 }45 private async Task<string> GetAuthorName(PuppeteerSharp.Page page)46 {47 var sellerInfoName = await page.WaitForSelectorAsync(".seller-info-name.js-seller-info-name a").EvaluateFunctionAsync<string>("element => element.innerHTML");48 sellerInfoName = sellerInfoName.Trim();49 var sellerInfoValueElement = await page.QuerySelectorAsync("div.seller-info-label + div.seller-info-value");50 if (sellerInfoValueElement != null)51 {52 var sellerInfoValue = (await sellerInfoValueElement.EvaluateFunctionAsync<string>("element => element.innerHTML")).Trim();53 sellerInfoName += ": " + sellerInfoValue;54 }55 return sellerInfoName;56 }57 private async Task<string> GetPhoneNumber(PuppeteerSharp.Page page)58 {59 string phoneImage = await page.WaitForSelectorAsync("div[data-marker='phone-popup/content'] img[data-marker='phone-popup/phone-image']").EvaluateFunctionAsync<string>("element => element.src");60 string imageStr = phoneImage.Substring(phoneImage.IndexOf(",") + 1).Trim();61 byte[] imageByte = System.Convert.FromBase64String(imageStr);62 using (var engine = new TesseractEngine("./tessdata", "eng", EngineMode.Default))63 {64 using (var memoryStream = new MemoryStream(imageByte))65 {66 var file = Pix.LoadFromMemory(memoryStream.ToArray());67 var page1 = engine.Process(file);68 return page1.GetText().Trim();69 }70 }71 }72 }73}...
test vueJS.csx
Source:test vueJS.csx
...50async Task waitForProgramEnd(){51 /*52 This stuff keeps the browser open until our program is done.53 */54 await page.EvaluateFunctionAsync(@"55 ()=> {56 window.programDone = false;57 }58 ");59 await page.WaitForExpressionAsync("window.programDone === true", new WaitForFunctionOptions{60 Timeout = 0 // disable timeout61 });62 Console.WriteLine("Program finished triggered");63 // program is done so close everything out64 await page.CloseAsync();65 await browser.CloseAsync();66}67await waitForProgramEnd();...
PuppeteerHelper.cs
Source:PuppeteerHelper.cs
...8 public static class PuppeteerHelper9 {10 public static async Task<string> GetTextboxValue(Page page, string selector)11 {12 JToken value = await page.EvaluateFunctionAsync(@"(selector) => {13 return document.querySelector(selector).value;14 }", selector);15 return value.Value<string>();16 }17 public static async Task<JToken> GetTableData(Page page, string dataSelector, List<ScrapeItemSetting> mappings)18 {19 var tData = await page.EvaluateFunctionAsync(@"(dataSelector, tableMapping) => {20 const data = Array.from(document.querySelectorAll(dataSelector));21 var items = [];22 data.forEach((item, index) => {23 var obj = {};24 tableMapping.forEach((i, idx) => {25 setObject(obj, i, item);26 });27 items.push(obj);28 });29 return items;30 }", dataSelector, mappings);31 return tData;32 }33 public static async Task<JToken> GetElements(Page page, List<ScrapeItemSetting> mappings)34 {35 var tData = await page.EvaluateFunctionAsync(@"(mappings) => {36 var items = [];37 mappings.forEach((i, idx) => {38 var obj = {};39 var element = $(document);40 setObject(obj, i, element);41 items.push(obj);42 });43 return items;44 }", mappings);45 return tData;46 }47 }48}...
CapturingService.cs
Source:CapturingService.cs
1using PuppeteerSharp;2namespace HeadfulBrowserAudioVideoCapturingService;3public class CapturingService4{5 public async Task StartCapturing(Page extensionPage) => await extensionPage.EvaluateFunctionAsync("START_RECORDING", new StartRecordingSettings());6 public async Task StopCapturing(Page extensionPage) => await extensionPage.EvaluateFunctionAsync("STOP_RECORDING");7}...
EvaluateFunctionAsync
Using AI Code Generation
1using System;2using System.Threading.Tasks;3using PuppeteerSharp;4{5 {6 static async Task Main(string[] args)7 {8 await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);9 var browser = await Puppeteer.LaunchAsync(new LaunchOptions { Headless = true });10 var page = await browser.NewPageAsync();11 var title = await page.EvaluateFunctionAsync<string>("() => document.title");12 Console.WriteLine(title);13 await browser.CloseAsync();14 }15 }16}17using System;18using System.Threading.Tasks;19using PuppeteerSharp;20{21 {22 static async Task Main(string[] args)23 {24 await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);25 var browser = await Puppeteer.LaunchAsync(new LaunchOptions { Headless = true });26 var page = await browser.NewPageAsync();27 var title = await page.MainFrame.EvaluateFunctionAsync<string>("() => document.title");28 Console.WriteLine(title);29 await browser.CloseAsync();30 }31 }32}33using System;34using System.Threading.Tasks;35using PuppeteerSharp;36{37 {38 static async Task Main(string[] args)39 {40 await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);41 var browser = await Puppeteer.LaunchAsync(new LaunchOptions { Headless = true });42 var page = await browser.NewPageAsync();43 var title = await page.EvaluateFunctionAsync<string>("() => document.title");44 Console.WriteLine(title);45 await browser.CloseAsync();46 }47 }48}49using System;50using System.Threading.Tasks;51using PuppeteerSharp;52{53 {54 static async Task Main(string[] args)55 {56 await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);
EvaluateFunctionAsync
Using AI Code Generation
1using System;2using System.Threading.Tasks;3using PuppeteerSharp;4{5 {6 static async Task Main(string[] args)7 {8 var browser = await Puppeteer.LaunchAsync(new LaunchOptions9 {10 });11 var page = await browser.NewPageAsync();12 var result = await page.EvaluateFunctionAsync("() => 1 + 2");13 Console.WriteLine(result);14 await browser.CloseAsync();15 }16 }17}18public Task<JsonElement> EvaluateExpressionAsync(string expression, object[] args = null)19using System;20using System.Threading.Tasks;21using PuppeteerSharp;22{23 {24 static async Task Main(string[] args)25 {26 var browser = await Puppeteer.LaunchAsync(new LaunchOptions27 {28 });29 var page = await browser.NewPageAsync();30 var result = await page.EvaluateExpressionAsync("1 + 2");31 Console.WriteLine(result);32 await browser.CloseAsync();33 }34 }35}36public Task<JSHandle> EvaluateFunctionHandleAsync(string function, object[] args = null)
EvaluateFunctionAsync
Using AI Code Generation
1using System;2using System.Threading.Tasks;3using PuppeteerSharp;4{5 {6 static async Task Main(string[] args)7 {8 {9 ExecutablePath = @"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe"10 };11 using (var browser = await Puppeteer.LaunchAsync(options))12 using (var page = await browser.NewPageAsync())13 {14 var result = await page.EvaluateFunctionAsync<string>("() => { return 'hello world'; }");15 Console.WriteLine(result);16 }17 }18 }19}
EvaluateFunctionAsync
Using AI Code Generation
1{2 {3 static void Main(string[] args)4 {5 var task = MainAsync(args);6 task.Wait();7 }8 static async Task MainAsync(string[] args)9 {10 var browser = await Puppeteer.LaunchAsync(new LaunchOptions11 {12 ExecutablePath = @"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe",13 Args = new string[] { "--no-sandbox" }14 });15 var page = await browser.NewPageAsync();16 var result = await page.EvaluateFunctionAsync("() => { return 1 + 2; }");17 Console.WriteLine(result);18 Console.ReadKey();19 }20 }21}
EvaluateFunctionAsync
Using AI Code Generation
1using System;2using System.Threading.Tasks;3using PuppeteerSharp;4{5 {6 static async Task Main(string[] args)7 {8 var browser = await Puppeteer.LaunchAsync(new LaunchOptions9 {10 });11 var page = await browser.NewPageAsync();12 var h1Value = await page.EvaluateFunctionAsync<string>("() => document.querySelector('h1').innerText");13 Console.WriteLine("h1 value is: " + h1Value);14 Console.ReadLine();15 await browser.CloseAsync();16 }17 }18}
Automation Testing Tutorials
Learn to execute automation testing from scratch with LambdaTest Learning Hub. Right from setting up the prerequisites to run your first automation test, to following best practices and diving deeper into advanced test scenarios. LambdaTest Learning Hubs compile a list of step-by-step guides to help you be proficient with different test automation frameworks i.e. Selenium, Cypress, TestNG etc.
LambdaTest Learning Hubs:
- JUnit Tutorial
- TestNG Tutorial
- Webdriver Tutorial
- WebDriverIO Tutorial
- Protractor Tutorial
- Selenium 4 Tutorial
- Jenkins Tutorial
- NUnit Tutorial
- Jest Tutorial
- Playwright Tutorial
- Cypress Tutorial
- PyTest Tutorial
YouTube
You could also refer to video tutorials over LambdaTest YouTube channel to get step by step demonstration from industry experts.
Run Puppeteer-sharp automation tests on LambdaTest cloud grid
Perform automation testing on 3000+ real desktop and mobile devices online.
Most used method in Page
- FrameManagerGetFrames
- workersValuesToArray
- PopupGetInvocationList
- clientDisconnected
- SetGeolocationAsync
- SetDragInterceptionAsync
- MetricsAsync
- TapAsync
- QuerySelectorAsync
- QuerySelectorAllAsync
- QuerySelectorAllHandleAsync
- XPathAsync
- EvaluateExpressionHandleAsync
- EvaluateFunctionHandleAsync
- EvaluateOnNewDocumentAsync
- EvaluateFunctionOnNewDocumentAsync
- EvaluateExpressionOnNewDocumentAsync
- QueryObjectsAsync
- SetRequestInterceptionAsync
- SetOfflineModeAsync
- EmulateNetworkConditionsAsync
- GetCookiesAsync
- SetCookieAsync
- DeleteCookieAsync
- AddScriptTagAsync
- AddStyleTagAsync
- ExposeFunctionAsync
- TResult
- GetContentAsync
- SetContentAsync
- GoToAsync
- PdfAsync
- PdfStreamAsync
- PdfDataAsync
- SetJavaScriptEnabledAsync
- SetBypassCSPAsync
- EmulateMediaAsync
- EmulateMediaTypeAsync
- EmulateMediaFeaturesAsync
- SetViewportAsync
- EmulateAsync
- ScreenshotAsync
- ScreenshotStreamAsync
- ScreenshotBase64Async
- ScreenshotDataAsync
- GetTitleAsync
- CloseAsync
- SetCacheEnabledAsync
- ClickAsync
- HoverAsync
- FocusAsync
- TypeAsync
- EvaluateExpressionAsync
- EvaluateFunctionAsync
- SetUserAgentAsync
- SetExtraHttpHeadersAsync
- AuthenticateAsync
- ReloadAsync
- SelectAsync
- WaitForTimeoutAsync
- WaitForFunctionAsync
- WaitForExpressionAsync
- WaitForSelectorAsync
- WaitForXPathAsync
- WaitForNavigationAsync
- WaitForNetworkIdleAsync
- Evaluate
- requestEventListener
- responseEventListener
- Cleanup
- WaitForRequestAsync
- WaitForResponseAsync
- WaitForFileChooserAsync
- GoBackAsync
- GoForwardAsync
- SetBurstModeOffAsync
- BringToFrontAsync
- EmulateVisionDeficiencyAsync
- EmulateTimezoneAsync
- EmulateIdleStateAsync
- EmulateCPUThrottlingAsync
- OnPopup
- InitializeAsync
- GoAsync
- ClientMessageReceived
- OnDetachedFromTarget
- OnTargetCrashed
- EmitMetrics
- HandleException
- OnDialog
- Dispose
- DisposeAsync
Try LambdaTest Now !!
Get 100 minutes of automation test minutes FREE!!
Was this article helpful?
