Puppeteer-Sharp is the .NET port of the Node library Puppeteer, which provides a high-level API to control headless Chrome or Chromium over the DevTools Protocol. Injecting custom scripts into a webpage with Puppeteer-Sharp typically involves the following process:
Initialize Puppeteer-Sharp: Start by installing the Puppeteer-Sharp NuGet package and creating a new instance of the
Browserobject.Open a new page: Launch a browser instance and open a new page.
Navigate to the target webpage: Direct the page to the URL where you want to inject the script.
Inject the custom script: Use methods like
EvaluateFunctionAsyncorAddScriptTagAsyncto execute or inject your custom JavaScript into the page.
Here's a step-by-step example of how you might inject a custom script into a webpage using Puppeteer-Sharp:
using System;
using System.Threading.Tasks;
using PuppeteerSharp;
class Program
{
public static async Task Main(string[] args)
{
// Initialize Puppeteer-Sharp
await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);
var browser = await Puppeteer.LaunchAsync(new LaunchOptions
{
Headless = true // Set to false if you want to see the browser
});
// Open a new page
var page = await browser.NewPageAsync();
// Navigate to the target webpage
await page.GoToAsync("https://example.com");
// Inject the custom script
// Option 1: Evaluate an anonymous function directly
await page.EvaluateFunctionAsync(@"() => {
// Your custom JavaScript code goes here
console.log('Custom script injected and executed.');
}");
// Option 2: Add a script tag to the head of the page
await page.AddScriptTagAsync(new AddTagOptions
{
Content = @"
// Your custom JavaScript code goes here
console.log('Custom script tag added to the page.');
"
});
// Do something with the page after the script is injected
// Close the browser
await browser.CloseAsync();
}
}
In this example, the EvaluateFunctionAsync method is used to inject and execute an anonymous JavaScript function directly on the page. The AddScriptTagAsync method, on the other hand, adds a <script> tag with the custom code to the page's <head>.
Make sure to handle any possible exceptions that might occur during these operations, as network issues, page navigation errors, or browser crashes can throw exceptions that should be caught and managed properly.
Remember that web scraping and the injection of scripts should be done responsibly and ethically. Always respect the website's terms of service and privacy policies, and ensure your activities do not violate any laws or regulations.
