@signalis/react

@signalis/react is the React integration library for signalis. It provides a Higher-Order Component that can be used to integrate React components with Signalis' reactivity system. In addition, @signalis/react provides a set of hooks for creating reactive entities inside of React components in a way that integrates tightly with React's rendering cycle. Finally, as a convenience, @signalis/react also re-exports all of @signalis/core, if you're using signalis in a React app, you can just install @signalis/react and get access to the entirety of signalis.

reactor

reactor is the main integration point for @signalis/react. Use reactor to wrap any component that you want to rerender in response to changes in reactive values.

const count = createSignal(0);

const Counter = () => {
  return (
    <div>
      <span>Count: {count.value}</span>
      <button type="button" onClick={() => count.value++}>
        +
      </button>
      <button type="button" onClick={() => count.value--}>
        -
      </button>
    </div>
  );
};

export default reactor(Counter);

reactor works by wrapping the component passed to it in a Proxy that that tells the component to re-render any time any reactive value used inside the component updates. Since it returns a Proxy, the component should still share all the same properties that the base component does, which means it should show up in React DevTools the same way it would normally.

useSignal

useSignal is a React hook for creating a Signal inside of a React component. It has the following signatures:

useSignal(value?: null | undefined): Signal<unknown>;
useSignal<T extends {}>(value: T): Signal<T>;

useSignal will return a Signal just like createSignal does, except that it uses useMemo under the hood to persist the Signal throughout component re-renders.

const Counter = () => {
  // Since we use `useMemo` under the hood, the Signal returned here will only be created once and is then re-used in subsequent rerenders.
  const count = useSignal(0);

  return (
    <div>
      <span>Count: {count.value}</span>
      <button type="button" onClick={() => count.value++}>
        +
      </button>
      <button type="button" onClick={() => count.value--}>
        -
      </button>
    </div>
  );
};

export default reactor(Counter);

useDerived<T>(fn: () => T): Derived<T>

Similar to useSignal, useDerived is used to create a Derived inside of a React component. useDerived makes use of useCallback and useMemo to ensure that the underlying Derived is only created once and is then re-used on subsequent rerenders.

const Counter = () => {
  const count = useSignal(0);
  const isOdd = useDerived(() => count.value % 2 !== 0);

  return (
    <div>
      <span>Count: {count.value}</span>
      <span>The count is {isOdd.value ? 'odd' : 'even'}</span>
      <button type="button" onClick={() => count.value++}>
        +
      </button>
      <button type="button" onClick={() => count.value--}>
        -
      </button>
    </div>
  );
};

export default reactor(Counter);

useSignalEffect(fn: () => void | (() => void)): void

useSignalEffect is a hook that allows you to create reactive effects inside of React components. It functions similarly to useEffect except that automatically tracks any reactive dependencies and will recompute whenever they change. useSignalEffect uses useEffect under the hood and returns the underlying effect's cleanup function so it will be automatically cleaned up the same way a regular useEffect will.

const Counter = () => {
  const count = useSignal(0);
  const isOdd = useDerived(() => count.value % 2 !== 0);

  useSignalEffect(() => {
    // will log every time `isOdd` changes, and will be cleaned up whenever this component is torn down.
    console.log(`The count is ${isOdd.value ? 'odd' : 'even'}`);
  });

  return (
    <div>
      <span>Count: {count.value}</span>
      <span>The count is {isOdd.value ? 'odd' : 'even'}</span>
      <button type="button" onClick={() => count.value++}>
        +
      </button>
      <button type="button" onClick={() => count.value--}>
        -
      </button>
    </div>
  );
};

export default reactor(Counter);