Tutorial series

Javascript Functional Programming

7 tutorials — follow in order for the best learning path.

1. Pure Functions and Side Effects

   Learn what pure functions are, how side effects impact your JavaScript code, and why they matter for writing predictable, testable programs.

   beginner
2. Higher-Order Functions in JavaScript: map, filter, compose

   Learn how JavaScript higher-order functions let you pass and return functions to build reusable, declarative code.

   beginner
3. Understanding Immutability in Modern JavaScript

   Learn JavaScript immutability: use spread operators and array methods for immutable updates, structuredClone for deep copies, and keep React state predictable.

   beginner
4. Function Composition and Pipelines

   Learn function composition in JavaScript with compose and pipe. Build readable data pipelines from small, reusable functions for clean, maintainable code.

   intermediate
5. Currying and Partial Application

   Learn how currying and partial application let you transform JavaScript functions into reusable, composable pieces.

   intermediate
6. Functors and Monads in JavaScript: From Array.map to Promise Chains

   Learn how functors and monads work in JavaScript through Array.map, Promise.then, custom Maybe types, and Either for error handling with composable chains.

   intermediate
7. Algebraic Data Types in JavaScript: Product and Sum Types

   Learn how algebraic data types work in JavaScript, including product types, sum types, and discriminated unions with TypeScript type narrowing.

   intermediate