Reactive Polling

Reactive Polling

Poll for changes to any value and trigger React re-renders when it changes.

Technique

Create a useReactive hook that uses useFrame to periodically check a selector function. When the value changes, update React state to trigger a re-render. Throttle with a configurable FPS.

Key Concepts

• Selector function returns the value to watch
• Compare with previous value to detect changes
• Only update state when value actually changes
• Throttle polling with useFrame's fps option
• Use sparingly for values that don't change frequently

Usage

const useReactive = <T,>(selector: () => T, fps = 30): T => {
  const [reactiveValue, setReactiveValue] = useState<T>(selector())
  const previousValueRef = useRef(reactiveValue)

  useFrame(
    () => {
      const newValue = selector()
      if (previousValueRef.current !== newValue) {
        previousValueRef.current = newValue
        setReactiveValue(newValue)
      }
    },
    { fps }
  )

  return reactiveValue
}

// Usage
const isAboveZero = useReactive(() => position.y > 0)

This skill is part of verekia's r3f-gamedev.

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