Functional Programming Patterns in JavaScript

Functional programming emphasizes immutability, pure functions, and composition. These patterns lead to code that's easier to test, debug, and reason about.

Core Concepts#

Pure Functions#

Immutability#

First-Class Functions#

Higher-Order Functions#

Map, Filter, Reduce#

Custom Higher-Order Functions#

Function Composition#

Pipe and Compose#

Practical Composition#

Currying and Partial Application#

Currying#

Partial Application#

Functors and Monads#

Maybe (Handling Null)#

Either (Error Handling)#

Practical Patterns#

Point-Free Style#

Pipeline Operator (Proposal)#

Conclusion#

Functional programming patterns make code more predictable and testable. Start with pure functions and immutability, then gradually adopt composition and higher-order functions.

You don't need to go full functional—even partial adoption improves code quality. Use these patterns where they make sense, and keep code readable.