Understanding the no-js Class in HTML

Last Updated : 10 Sep, 2026

The no-js class is commonly added to the <html> element to provide different styles or functionality depending on whether JavaScript is available in the browser.

  • It allows CSS to target pages when JavaScript is disabled.
  • JavaScript can replace the no-js class with a js class when scripting is enabled.
  • It is commonly used for progressive enhancement and JavaScript-dependent features.

Approach: Using the no-js Class with JavaScript Detection

In this approach, the no-js class is initially added to the <html> element. When JavaScript runs, it replaces no-js with js, allowing CSS to apply different styles based on JavaScript availability.

Example:

html 
<!DOCTYPE html>
<html lang="en" class="no-js">

<head>
    <script>
        document.documentElement.className =
            document.documentElement.className
                .replace(/\bno-js\b/g, "") + " js";
    </script>

    <title>no-js Class Example</title>
</head>

<body>
    <h1>GeeksforGeeks</h1>
</body>

</html>

Output:

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