Online Javascript Compiler

Welcome! You've just opened a direct gateway to the language that powers the interactive web. If you've ever clicked a button on a website that changed the page, seen a pop-up alert, or watched an image gallery slide, you've seen JavaScript in action.

While JavaScript traditionally runs in the browser, this tool (powered by a runtime like Node.js) lets you execute and test your JS code right here, right now. No setup needed!

Write Your JS: Enter your JavaScript code into the text editor.

Click Run: Press the "Run" button to execute your script.

Check the Output: The results from your code will be displayed in the output console below.

Your First JavaScript Program: "Hello, World!"

Let's use the console to log our first message. The console is a developer's best friend for seeing what's happening behind the scenes.

console.log("Hello from JavaScript on docodehere.com!");

console.log() is the primary way developers "print" information in JavaScript. It logs messages to a developer console.

The text inside the parentheses (...) is the argument we're giving to the function—it's the message we want to display.

The ; at the end marks the end of a statement. While sometimes optional in modern JavaScript, it's a good habit to use it!

Let's Try Something More: A Simple Function

Functions are the building blocks of JavaScript. They allow you to bundle up code to perform a task. Let's create a function that greets a user.

// Define a function that takes a name as an input
function greet(name) {
  console.log("Hello, " + name + "! Welcome.");
}

// Now, let's call our function with a specific name
greet("Alex");
greet("Maria");

When you run this, you'll see two different greetings. You've created a reusable piece of code and used it twice!

They are completely different languages, despite the similar name! Think of it like "Car" and "Carpet." JavaScript is primarily for web development, while Java is a general-purpose language often used for back-end systems and Android apps.

You might see undefined if you try to use a variable that hasn't been given a value yet. Always make sure your variables are declared and assigned before you use them.

The MDN Web Docs (Mozilla Developer Network) is the gold standard for JavaScript documentation. For tutorials, sites like javascript.info are excellent.

Enjoy exploring the world of JavaScript!