Javascript Mastery

---
version: 4.1.0-fractal
name: javascript-mastery
description: "Comprehensive JavaScript reference covering 33+ essential concepts every developer should know. From fundamentals like primitives and closures to advanced patterns like async/await and functional programming. Use when explaining JS concepts, debugging JavaScript issues, or teaching JavaScript fundamentals."
---

# 🧠 JavaScript Mastery

> 33+ essential JavaScript concepts every developer should know, inspired by [33-js-concepts](https://github.com/leonardomso/33-js-concepts).

## When to Use This Skill

Use this skill when:

- Explaining JavaScript concepts
- Debugging tricky JS behavior
- Teaching JavaScript fundamentals
- Reviewing code for JS best practices
- Understanding language quirks

---

## 1. Fundamentals

## 🧠 Knowledge Modules (Fractal Skills)

### 1. [1.1 Primitive Types](./sub-skills/11-primitive-types.md)
### 2. [1.2 Type Coercion](./sub-skills/12-type-coercion.md)
### 3. [1.3 Equality Operators](./sub-skills/13-equality-operators.md)
### 4. [2.1 Scope Types](./sub-skills/21-scope-types.md)
### 5. [2.2 Closures](./sub-skills/22-closures.md)
### 6. [2.3 var vs let vs const](./sub-skills/23-var-vs-let-vs-const.md)
### 7. [3.1 Call Stack](./sub-skills/31-call-stack.md)
### 8. [3.2 Hoisting](./sub-skills/32-hoisting.md)
### 9. [3.3 this Keyword](./sub-skills/33-this-keyword.md)
### 10. [4.1 Event Loop](./sub-skills/41-event-loop.md)
### 11. [4.2 Callbacks](./sub-skills/42-callbacks.md)
### 12. [4.3 Promises](./sub-skills/43-promises.md)
### 13. [4.4 async/await](./sub-skills/44-asyncawait.md)
### 14. [5.1 Higher-Order Functions](./sub-skills/51-higher-order-functions.md)
### 15. [5.2 Pure Functions](./sub-skills/52-pure-functions.md)
### 16. [5.3 map, filter, reduce](./sub-skills/53-map-filter-reduce.md)
### 17. [5.4 Currying & Composition](./sub-skills/54-currying-composition.md)
### 18. [6.1 Prototypal Inheritance](./sub-skills/61-prototypal-inheritance.md)
### 19. [6.2 Object Methods](./sub-skills/62-object-methods.md)
### 20. [7.1 Destructuring](./sub-skills/71-destructuring.md)
### 21. [7.2 Spread & Rest](./sub-skills/72-spread-rest.md)
### 22. [7.3 Modules](./sub-skills/73-modules.md)
### 23. [7.4 Optional Chaining & Nullish Coalescing](./sub-skills/74-optional-chaining-nullish-coalescing.md)