I wish to replace text in a web page in C#

Question

Here is the code that I am using

 private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
     IHTMLDocument2 doc2 = webBrowser1.Document.DomDocument as IHTMLDocument2;
     StringBuilder html = new StringBuilder(doc2.body.outerHTML);

     String substitution = "<span style='background-color: rgb(255, 255, 0);'> sensor </span>";
     html.Replace("sensor", substitution);

     doc2.body.innerHTML = html.ToString();

       }

It works, but the I cannot use the form nor the web browser

I have tried to added

webBrowser1.Document.Write(html.ToString()); //after doc2 at the end

But the webpage displayed is not formmatted correctly

I would be grateful, to get this fixed

I suspect that `webBrowser1_DocumentCompleted` occurs too late for this to work. — Robert Harvey, Dec 08 '19 at 21:06
Thanks for responsing .. Can I fix this .. slow down the webBrowser_DocumentCompleted — dwk, Dec 08 '19 at 21:14
That's not how events work. I think you need to re-evaluate your approach. — Robert Harvey, Dec 08 '19 at 21:31

score 1 · Accepted Answer · answered Dec 09 '19 at 11:05

You first need to find your element in the HTMLDocument DOM and then manipulate the innerHTML property with the relevant HTML.

There are a variety of ways to do this, including injecting javascript (here) or using HtmlAgilityPack.

The following code uses GetElementsByTagName DOM function to iterate over the span tags in the document on this site: https://www.w3schools.com/html/

It replaces all span text's including "Tutorial" with the html snippet your provided.

private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    var elements = webBrowser1.Document.GetElementsByTagName("span");
    foreach (HtmlElement element in elements)
    {
        if(string.IsNullOrEmpty(element.InnerText)) 
            continue;

        if (element.InnerText.Contains("Tutorial"))
        {
            element.InnerHtml = "<span style='background-color: rgb(255, 255, 0);'> sensor </span>";
        }
    }
}

I wish to replace text in a web page in C#

1 Answers1