JavaScript is a high-level, interpreted programming language that makes web pages interactive and dynamic. It is one of the core technologies of the web, along with HTML (structure) and CSS (style).

What is High Level Language?

A high-level language is a human-readable programming language that uses English-like words.

what is interpreted language?

An interpreted language runs code one line at a time using an interpreter, without needing to compile it first.

Key Characteristics

• Single-threaded:

  JavaScript runs on a single call stack, meaning it can only execute one task at a time.

• Synchronous by default:

  JavaScript executes code line by line, in order. Each operation must complete before the next one starts.

• Asynchronous capabilities:

  Even though it’s single-threaded, JavaScript uses the event loop and Web APIs to handle tasks like timers, API requests, and user interactions without blocking the main thread. This makes it feel "multi-tasking."

• Multi-paradigm:

  Supports object-oriented, functional, and event-driven programming styles.

  // Object-oriented
  class Person {
    constructor(name) { this.name = name; }
    greet() { console.log(`Hello, ${this.name}`); }
  }
  const p = new Person("Anik");
  p.greet();
  
  // Functional
  const add = (a, b) => a + b;
  console.log(add(2, 3));
  
  // Event-driven example in browser
  const button = document.createElement('button');
  button.textContent = 'Click me';
  document.body.appendChild(button);
  
  button.addEventListener('click', () => {
    alert('Hi there!');
  });
  

• Runs everywhere:

  • In the browser (for client-side interactivity)
  • On the server (using Node.js)

JavaScript is a single-threaded, synchronous (by default) programming language with powerful asynchronous features, designed to make web applications interactive, dynamic, and responsive.

Data Types

Primitive Data Types

• Number

let age = 25; 
let pi = 3.14;.

• String

 let name = ‘John’;

• Boolean