Signals standardization across JS frameworks
TC39 moves to standardize signals as JS frameworks converge on fine-grained reactivity NDC ConferencesTL;DW
- Signals are reactive variables that automatically recalculate dependent values when their dependencies change, eliminating manual recalculation work in application state management.
- JavaScript frameworks shifted from pull-based rendering (server-side templates) to push-based DOM updates (jQuery era) to gain performance, losing predictability in the process.
- Knockout introduced observables and data binding to regain the predictability of pull-based approaches while maintaining push performance—a pattern Vue, Svelte, Solid, and Angular have adopted.
- React deliberately uses the pull approach (whole-app re-renders on state change) with memoization and virtual DOM instead of signals, prioritizing consistency and predictability over fine-grained reactivity.
- Signal implementations must handle order-of-recalculation (topological sorting), batching updates to prevent UI glitches, and dirty-state tracking to skip unnecessary recalculations.
- TC39 proposal aims to standardize signals in JavaScript core language rather than having each framework reinvent the wheel with custom implementations.
- Solid pioneered the 'push and pull' hybrid approach for signals: pushing state changes but only recalculating derived values when actually read from the UI.
- React's new compiler automatically memoizes functions and state, achieving similar efficiency gains to signal-based frameworks without changing React's fundamental pull-based architecture.
TL;DW
- Signals are reactive variables that automatically recalculate dependent values when their dependencies change, eliminating manual recalculation work in application state management.
- JavaScript frameworks shifted from pull-based rendering (server-side templates) to push-based DOM updates (jQuery era) to gain performance, losing predictability in the process.
- Knockout introduced observables and data binding to regain the predictability of pull-based approaches while maintaining push performance—a pattern Vue, Svelte, Solid, and Angular have adopted.
- React deliberately uses the pull approach (whole-app re-renders on state change) with memoization and virtual DOM instead of signals, prioritizing consistency and predictability over fine-grained reactivity.
- Signal implementations must handle order-of-recalculation (topological sorting), batching updates to prevent UI glitches, and dirty-state tracking to skip unnecessary recalculations.
- TC39 proposal aims to standardize signals in JavaScript core language rather than having each framework reinvent the wheel with custom implementations.
- Solid pioneered the 'push and pull' hybrid approach for signals: pushing state changes but only recalculating derived values when actually read from the UI.
- React's new compiler automatically memoizes functions and state, achieving similar efficiency gains to signal-based frameworks without changing React's fundamental pull-based architecture.
Traces the shift from React's pull model (re-render + memoize) to signals' push model (dependency tracking, surgical DOM updates), with a live implementation covering subscriptions, dirty-state tracking, and batching. Closes with the TC39 signals proposal and what native browser support eliminates for framework authors.