How to Run JavaScript

Before diving deep into how JavaScript works, it’s important to know where and how you can run your code. Whether you’re building websites, testing small snippets, or creating backend apps — JavaScript can run in many environments.

Let’s explore the most common and practical ways to run JavaScript — from browsers to your local machine.

1. Run JavaScript in the Browser Console

Every modern browser (like Chrome, Firefox, Edge) comes with built-in developer tools — including a JavaScript console.

Open Chrome (or any modern browser)
Right-click on the page → Click Inspect
Go to the Console tab
Type the following code and press Enter:

console.log("Hello from JDCodebase!");

You’ll see the message appear instantly in the console. Great for quick testing and learning.

2. Use Online Editors (Playgrounds)

If you don’t want to install anything, you can test your code directly online using JavaScript playgrounds. These are simple to use and beginner-friendly.

[PlayCode](https://playcode.io)
[JSFiddle](https://jsfiddle.net)
[Replit](https://replit.com)
[JDCodebase Playground](/playground)

These platforms let you write and run HTML, CSS, and JavaScript together with instant results.

3. Run JavaScript Locally with Node.js

Node.js allows JavaScript to run outside the browser — directly on your computer. Perfect for backend apps and tools.

Download and install Node.js from [nodejs.org](https://nodejs.org)
Create a file named `index.js`
Write JS code like this:

console.log("Hello from Node.js!");

Open your terminal or command prompt
Run: `node index.js`

4. Embed JavaScript in an HTML File

You can also run JavaScript inside a webpage using the <script> tag.

<!DOCTYPE html>
<html>
  <body>
    <script>
      alert("Hello from JDCodebase!");
    </script>
  </body>
</html>

Save this as an `.html` file and open it in your browser. You’ll see an alert popup.

Which One Should You Use?

Here’s a quick comparison to help you decide where to start:

Method	Setup Needed	Best For
Browser Console	No	Quick testing, learning basics
Online Editors	No	Practicing without setup
Node.js	Yes	Backend, CLI tools, local testing
HTML + JS	No	Frontend development, web projects

Conclusion

JavaScript runs in many places — browser, online editors, your computer, or even inside an HTML file. Start with the console or JDCodebase Playground, and expand as you grow!

How to Run JavaScript

JavaScript Versions Variables (var, let, const)