JavaScript - Enabling JavaScript

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Overview

Estimated time: 10–15 minutes

Most browsers have JavaScript enabled by default. If scripts don't run, use the quick test below and check settings.

Learning Objectives

Verify whether JavaScript is enabled in your browser.
Know where to turn it on in popular browsers.
Troubleshoot common issues (CSP, extensions, 404s).

Prerequisites

JavaScript - Introduction

Quick Test

<!DOCTYPE html>
<html>
  <body>
    <h1>JS Check</h1>
    <script>document.body.insertAdjacentHTML('beforeend', '<p>JavaScript is enabled</p>');</script>
    <noscript><p style="color:red">JavaScript appears to be disabled.</p></noscript>
  </body>
</html>

Enable in Popular Browsers

Chrome: Settings → Privacy and security → Site settings → JavaScript → Sites can use JavaScript.
Safari (macOS): Safari → Settings → Security → Enable JavaScript.
Firefox: JS is enabled by default. If toggled, set javascript.enabled to true in about:config.
Edge: Settings → Cookies and site permissions → JavaScript → Allowed.

Troubleshooting

Check the DevTools Console for errors (404 on script file, syntax errors).
Ensure your <script src> path and filename are correct.
Extensions (ad blockers) may block scripts — try a private window with extensions disabled.
Hosted pages may use CSP that blocks inline scripts. Prefer external files or add required nonce/hash.

Checks for Understanding

How can you quickly confirm that JavaScript is enabled on a page?
Where do you enable JavaScript in Chrome or Safari?

Show answers

Add a small inline script that writes to the DOM (or check for a message in the Console); use