How to Inject JavaScript into a WebBrowser Control Using C#?

Inject JavaScript code into the WebBrowser control in C#

This article describes a technique for injecting JavaScript code into the WebBrowser control Document Object Model (DOM). This approach stems from the difficulty of manipulating script elements directly using the InnerHtml attribute.

The following steps will guide you through the process:

1. Get the head element of the current document in the WebBrowser control:

   HtmlElement head = webBrowser1.Document.GetElementsByTagName("head")[0];

2. Create a script element using the CreateElement method:

   HtmlElement scriptEl = webBrowser1.Document.CreateElement("script");

3. Converts script elements into IHTMLScriptElement interfaces. This step is crucial because it allows access to the interface that defines the "text" attribute of the script element:

   IHTMLScriptElement element = (IHTMLScriptElement)scriptEl.DomElement;

4. Set the text attribute to the desired JavaScript code:

   element.text = "function sayHello() { alert('hello') }";

5. Append a script element to the head element to inject script into the DOM:

   head.AppendChild(scriptEl);

6. To execute the injected JavaScript function, call the Document method on the WebBrowser control's InvokeScript object:

   webBrowser1.Document.InvokeScript("sayHello");

With this method, you can inject JavaScript code into the DOM of the WebBrowser control, thereby dynamically modifying its functionality and behavior.

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