# Fundamentals

> TypeScript type system fundamentals and basic typing patterns

- Skill: `pluginagentmarketplace/fundamentals-2` (Agent Skill, multi-file: 6 files)
- Install (CLI): `npx skillmds@latest add pluginagentmarketplace/fundamentals-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pluginagentmarketplace/fundamentals-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: pluginagentmarketplace (https://skillmd.com/u/pluginagentmarketplace)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/pluginagentmarketplace/fundamentals-2

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# TypeScript Fundamentals Skill

## Overview
Master TypeScript's type system fundamentals including basic types, interfaces, and type annotations.

## Topics Covered

### Basic Types
- Primitive types (string, number, boolean)
- Arrays and tuples
- Enums
- Any, unknown, never, void
- Null and undefined handling

### Type Annotations
- Variable annotations
- Function parameters and returns
- Object type annotations
- Type inference
- Type assertions

### Interfaces
- Interface declaration
- Optional properties
- Readonly properties
- Index signatures
- Interface extension

### Type Aliases
- Type alias syntax
- Union types
- Intersection types
- Literal types
- Type narrowing

### Functions
- Function type expressions
- Call signatures
- Overloads
- Generic functions
- Rest parameters

## Prerequisites
- JavaScript fundamentals
- ES6+ features

## Learning Outcomes
- Write type-safe code
- Use interfaces effectively
- Apply type narrowing
- Understand type inference