useObservable Hook

Since all the fundamental constructs like Units, Actions, Systems, and Clusters are Observable, it makes sense that we create a custom Hook to easily bind their value to a component's local state. useObservable is much simpler and ergonomic to use than useUnit.

useObservable Hook:

TypeScript

import { useState, useEffect } from "react";
import { Observable } from "rxjs";

export type ObservableValueType<T> = T extends Observable<infer X> ? X : never;

export function useObservable<U extends Observable<any>>($: U) {
  type T = ObservableValueType<U>;
  const [value, setValue] = useState<T>();

  useEffect(() => {
    const subscription = $.subscribe(setValue);
    return () => subscription.unsubscribe();
  }, [$]);

  return value;
}

JavaScript

import { useState, useEffect } from "react";
import { Observable } from "rxjs";

export function useObservable(observable) {
  const [value, setValue] = useState();

  useEffect(() => {
    const subscription = observable.subscribe(setValue);
    return () => subscription.unsubscribe();
  }, [observable]);

  return value;
}

Example:

// create a Unit or System, Cluster, Action
const listUnit = new ListUnit({initialValue: ['🤯']});

// a simple component
function Visualizer() {
  const value = useObservable(listUnit);

  return <span>{value}</span>;
}

// it'll render this immediately and will render any future values
🤯

More Examples:

• StackBlitz example that shares a Unit among multiple components.

• Simple Counter example.

• See this for usage in combination with AsyncSystem.