What is JavaScript?

JavaScript is the interpreted programming language that brings the web to life. Unlike HTML (structure) and CSS (design), JavaScript allows pages to be interactive and dynamic.

A Bit of History

It was born in 1995, created by Brendan Eich in just 10 days. Although it started as a “toy” for small tricks, today it’s one of the most powerful and versatile languages in the world.

What Does “Client-Side” Mean?

When we say JS runs on the client, it means it executes directly in the visitor’s browser. This allows:

  • Modifying the page in real time
  • Validating forms instantly
  • Creating visual effects and animations
  • Communicating with servers without reloading the page

What About “Server-Side”?

Thanks to environments like Node.js, JavaScript can also be used to build the “brain” of applications that handle databases and files.

Displaying or Retrieving Data

There are several ways to interact with the user:

  1. console.log(): Shows messages in the browser console (F12)
  2. alert(): Shows a pop-up notification
  3. prompt(): Opens a dialog for user input
  4. document.write(): Writes content directly into the HTML body (use with caution)

Example:

const name = prompt("What's your name?");
console.log("Hello, " + name);
alert("Welcome to Programierds");