React Scroll Effects Without External Libraries

React Scroll Effects Without External Libraries Scroll is the most fundamental user interaction on the web. Progress bars that fill as you read, headers that shrink and stick, modals that lock the page behind them, "scroll to section" buttons -- these effects appear on nearly every modern site. Yet implementing them correctly in React means juggling addEventListener, IntersectionObserver, overflow styles, and a surprising number of edge cases. Most developers either pull in a heavy animation library or spend hours writing brittle imperative code. This post takes a different path. We will tackle six common scroll scenarios, starting each time with the manual implementation so you understand the mechanics, then replacing it with a purpose-built hook from ReactUse (@reactuses/core). ReactUse is an open-source collection of 100+ React hooks that wrap common browser and element interactions into simple, composable APIs. By the end you will have a toolkit of composable, SSR-safe hooks that h