SolidJS signals

Team Radar ships SolidJS — reactive primitives without a virtual DOM diff on every poll.

Core primitives

const [count, setCount] = createSignal(0);
const doubled = () => count() * 2;
createEffect(() => console.log(doubled()));

Reading count() inside doubled or an effect subscribes that computation — only those nodes update.

SolidSignalGraph — increment and watch the dependency chain light up.

Radar connection

When Redis SSE pushes a new event count, only the bound text node changes — not the whole dashboard shell.

See apps/radar/ — signals for UI, TanStack Query for server JSON (next lesson).

Teach-back prompt

How is a Solid signal different from React useState triggering a component re-render?