Conquering JavaScript Hydration

JavaScript hydration — the process of reattaching interactivity after server-side rendering — has long been a performance bottleneck for web frameworks. Ryan Carniato traces the journey that led the Marko team and Misko Hevery (creator of Angular and Qwik) to independently arrive at 'resumability': a technique where the server serializes reactive state so the browser can resume execution without re-running components. The key insight is that only browser-specific code (like effects and global event handlers) needs to execute at hydration time, eliminating redundant component re-execution. Both Qwik and Marko 6 are implementing this approach, with Qwik adding granular progressive code loading on top. The author argues this marks hydration as a largely solved problem, opening a new era for web development.