// @nuget: HtmlAgilityPack

​

using System;

using HtmlAgilityPack;

public class Program

{

    public static void Main()

    {

        var html =

        @"<div id='div1'> hello </div>";

​

        var htmlDoc = new HtmlDocument();

        htmlDoc.LoadHtml(html);

​

        Console.WriteLine("\n****Before child node replaced****\n");

        Console.WriteLine(htmlDoc.Text);        

​

        HtmlNode oldChild =  htmlDoc.DocumentNode.SelectSingleNode("//div[@id='div1']");

        HtmlNode newChild = HtmlNode.CreateNode("<h2> This is h2 new child node</h2>");

        Console.WriteLine("Node Name: " + oldChild.Name);

​

        oldChild.ParentNode.ReplaceChild(newChild, oldChild);

​

        Console.WriteLine("\n****After child node replaced****\n");

        Console.WriteLine(htmlDoc.Text);

    }

}