Functional-Light JavaScript is an online book that teaches functional programming principles through a pragmatic JavaScript lens. Instead of insisting on strict purity, it adopts a balanced approach that keeps code practical while showing how immutability, composition, and declarative thinking improve quality. Chapters build up from values and closures to higher-order functions, list operations, transducing, and async patterns, all grounded in idiomatic JS. The writing favors intuition and...