How to Use CSS Selector in C# - QuerySelector & QuerySelectorAll in HTML .NET

readme.md

You can read more details at: Use CSS Selectors in HTML using C#

Queryselector.cs

// Prepare path to source HTML file
string documentPath = "queryselector.html";

// Create an instance of an HTML document
var document = new Aspose.Html.HTMLDocument(documentPath);

// Here we create a CSS Selector that extracts the first paragraph element in the document
var element = document.QuerySelector("p");

// Print content of the first paragraph  
Console.WriteLine(element.InnerHTML);
// output: The QuerySelector() method returns the first element in the document that matches the specified selector.

// Set style attribute with properties for the selected element               
element.SetAttribute("style", "color:rgb(50,150,200); background-color:#e1f0fe;");

// Save the HTML document to a file
document.Save("queryselector-p.html");

QuerySelectorAll.cs

// Prepare output path for HTML document saving
string savePath = "css-selector-color.html";

// Prepare path to source HTML file
string documentPath = "spring.html";

// Create an instance of an HTML document
var document = new Aspose.Html.HTMLDocument(documentPath);

// Here we create a CSS Selector that extracts all elements whose 'class' attribute equals 'square2'
var elements = document.QuerySelectorAll(".square2");

// Iterate over the resulted list of elements
foreach (Aspose.Html.HTMLElement element in elements)
{
    // Set style attribute with new background-color property
    element.Style.BackgroundColor = "#b0d7fb";
}

// Save the HTML document to a file
document.Save(savePath);