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JavaScript Crash Course

JavaScript is the most ubiquitous programming language in the world. It runs in every browser, powers servers with Node.js, builds mobile apps, and even trains machine learning models. If you learn one language, make it JavaScript.
This crash course is designed to take you from “Hello World” to understanding closures, prototypes, async/await, and modern ES6+ features.

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Why JavaScript?

JavaScript has evolved from a simple scripting language to a versatile powerhouse.

Runs Everywhere

From browsers to servers (Node.js) to mobile (React Native) to desktop (Electron) — JavaScript is truly universal.

Massive Ecosystem

npm is the world’s largest package registry with over 2 million packages. There’s a library for everything.

Async by Nature

Built-in event loop and async primitives make handling I/O, network calls, and user interactions seamless.

Rapid Evolution

With yearly ECMAScript updates, JavaScript keeps getting better: async/await, modules, optional chaining, and more.

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Course Roadmap

We will peel back the layers of abstraction to understand how JavaScript really works.
1

Fundamentals

Understand variables, types, operators, and control flow. Start Learning
2

Functions & Scope

First-class functions, closures, and the execution context. Explore Functions
3

Objects & Prototypes

Objects, prototypal inheritance, and the this keyword. Master Objects
4

Async JavaScript

Callbacks, Promises, async/await, and the Event Loop. Go Async
5

Modern JavaScript (ES6+)

Destructuring, modules, classes, and the latest features. Go Modern
6

DOM & Browser APIs

Manipulating the DOM, handling events, and browser APIs. Build for the Web

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Prerequisites

  • Basic programming knowledge (any language).
  • A modern browser (Chrome, Firefox, Edge).
  • Node.js installed for running JS outside the browser (node -v).
  • A code editor (VS Code is highly recommended).

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The JavaScript Philosophy

“Any application that can be written in JavaScript, will eventually be written in JavaScript.” — Atwood’s Law
JavaScript is a multi-paradigm language. You can write object-oriented, functional, or procedural code. It’s dynamically typed (flexibility at the cost of runtime errors), and single-threaded with an event-driven architecture. 
// A taste of JavaScript
const greet = (name) => `Hello, ${name}!`;

const names = ['Alice', 'Bob', 'Charlie'];

names
  .filter(name => name.startsWith('A'))
  .map(greet)
  .forEach(console.log);

// Output: "Hello, Alice!"