Higher Order Functions

Closures

A closure is a function that retains access to variables from the scope in which it was defined, even after that outer scope has finished executing.

Higher-Order Functions

A higher-order function is a function that takes one or more functions as arguments, returns a function as its result, or both.

Middleware

Middleware is software that sits between an incoming request and the final application logic, intercepting and processing requests (or responses) to handle cro…

Higher-Order Functions

Learn how Scala functions that accept or return other functions enable powerful, reusable abstractions like map, filter, fold, and currying.

Functional Programming Concepts Cheat Sheet

Pure functions, immutability, higher-order functions, function composition, and currying — the core ideas behind functional programming, explained with runnabl…

What Is Currying in JavaScript?

Currying is the technique of transforming a function that takes multiple arguments into a sequence of functions that each take a single argument, returning a n…

What Is Memoization in JavaScript?

Memoization is an optimization technique that caches the return value of an expensive, pure function keyed by its input arguments, so that calling the function…

map, filter, and reduce: How Do They Differ?

map transforms every element into a new array of the same length, filter selects a subset of elements into a new (possibly shorter) array based on a predicate,…