Signals and Modern Reactivity
The paradigm shift happening right now. Signals, fine-grained reactivity, and how frameworks like Solid, Vue 3, and Angular are fundamentally different from React's virtual DOM model.
The fundamental architectural split in frontend: React's top-down re-render model versus signals' push-based fine-grained reactivity. Why each exists, what each trades away, and when each wins.
The three building blocks of every signal system: reactive values (signal), derived computations (computed), and side effects (effect). How they connect, how they stay glitch-free, and the push-vs-pull evaluation debate.
How signals know what depends on what without you telling them. The tracking context pattern, the global computation stack, subscription graphs, cleanup on re-execution, the diamond dependency problem, and batching.
How SolidJS achieves React-like DX with signal-based performance. Components run once, JSX compiles to real DOM operations, no virtual DOM, and fine-grained updates. The framework that proved signals could work at scale.
Vue 3's Proxy-based reactivity system: ref vs reactive, computed and watch, the Composition API pattern, how Vue tracks nested object mutations, and Vue's compiler optimizations that make the virtual DOM nearly as fast as no-VDOM frameworks.
Angular's signal revolution: signal(), computed(), effect(), the move away from Zone.js, zoneless change detection, signal-based components, and how Angular is retrofitting fine-grained reactivity into a mature framework. Includes Angular 21's zoneless-by-default architecture.
Using @preact/signals-react to bring fine-grained reactivity into React components. How it bypasses React's re-render model, the controversy around breaking React's rules, performance wins, and real trade-offs with DevTools, Suspense, and concurrent features.
The TC39 Signals proposal (Stage 1): standardizing reactive primitives in JavaScript itself. Signal.State, Signal.Computed, the Watcher API, framework interop, polyfills, and what it means for the ecosystem if signals become a language feature.
CSR, SSR, SSG, ISR, streaming SSR, RSC, islands architecture, and resumability (Qwik). A decision framework for choosing the right pattern based on content dynamism, personalization, SEO, time-to-interactive, and infrastructure.
Test your understanding of signals, reactive primitives, framework-specific implementations, dependency tracking, and rendering pattern decisions across the modern reactivity landscape.