rehuy

rehuy.js

const ctx = [];

function addEffect(current, effects) {
  effects.add(current);
  current.deps.add(effects);
}

function createAtom(value) {
  const effects = new Set();

  const getState = () => {
    const current = ctx[ctx.length - 1];
    if (current) addEffect(current, effects);

    return value;
  };

  const update = (nextValue) => {
    value = nextValue;

    for (const sub of [...effects]) {
      sub.execute();
    }
  };

  return { getState, update };
}

function cleanup(current) {
  for (const dep of current.deps) {
    dep.delete(current);
  }
  current.deps.clear();
}

function createEffect(fn) {
  const execute = () => {
    cleanup(current);
    ctx.push(current);

    try {
      fn();
    } finally {
      ctx.pop();
    }
  };

  const current = {
    deps: new Set(),
    execute
  };

  execute();
}

const atom = createAtom(5);

console.log(ctx);

createEffect(() => console.log(atom.getState()));

atom.update(10);
atom.update(5);
atom.update(11);