为所有孩子加课

Question

I have some html,.. for example:

<div id='mainDiv'>
   <ul>
      <li>1</li>
      <li>2</li>
      <li>3</li>
   </ul>
   <div><span>text</span></div>
   <div><span>another text</span></div>
   <p>lalala</p>
</div>

How I can to foreach all childs from mainDiv and add some data-attr in every children

HtmlNode mainDiv = document.DocumentNode.SelectSingleNode("//div[@id='mainDiv']");

Answer 1

Alternative just iterate over the children

class Program
{
    static void Main(string[] args)
    {
        HtmlDocument document = new HtmlDocument();
        document.Load("Demo.html");

        HtmlNode mainDiv = document.DocumentNode.SelectSingleNode("//div[@id='mainDiv']");

        foreach (var child in mainDiv.ChildNodes)
        {
            if (child.Attributes.Any(att=> att.Name == "class"))
            {
                child.Attributes["class"].Value = "data-attr";
            }
            else
            {
                child.Attributes.Add("class", "data-attr");
            }
        }

        document.Save("Demo.html");
    }
}

Or all descendants:

class Program
{
    static void Main(string[] args)
    {
        HtmlDocument document = new HtmlDocument();
        document.Load("Demo.html");

        HtmlNode mainDiv = document.DocumentNode.SelectSingleNode("//div[@id='mainDiv']");

        foreach (var child in mainDiv.Descendants())
        {
            if (child.Attributes.Any(att=> att.Name == "class"))
            {
                child.Attributes["class"].Value = "data-attr";
            }
            else
            {
                child.Attributes.Add("class", "data-attr");
            }
        }

        document.Save("Demo.html");
    }
}