RivoCode

JavaScript Fundamentals · Introduction · Lesson 1 of 48

What is JavaScript?

Concept

What is JavaScript?

JavaScript is the programming language of the web. It runs in every browser, adds interactivity to HTML and CSS pages, and now also runs on servers via Node.js.

Alongside HTML and CSS, JavaScript is one of the three core technologies of the web. HTML structures a page, CSS styles it, and JavaScript makes it interactive.

By the end of this lesson
  • Explain the core idea behind What is JavaScript?.
  • Predict output before running a change.
  • Test one realistic and one unusual input.
  • Use the result to make the next decision.
How to study this page
  1. 1. Read one concept.
  2. 2. Change the example.
  3. 3. Run, compare, and explain.
  4. 4. Complete the challenge below.
ExampleRunnable
console.log("Hello, RivoCode!");
Try it Yourself »
Writing to the page instead of the console
document.write("JavaScript can write directly into a page.");
Note: document.write() is handy for quick demos, but real apps update specific elements instead of the whole page.

Good to know

JavaScript has nothing to do with Java — the similar name was purely a 1995 marketing decision. They are completely different languages.

Self-check before continuing

Without looking at the example, describe what changes when you modify one input in What is JavaScript?. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Open the console and print your name using console.log().

Loading editor…

Console

Output will appear here...