uhooks with propagated states

Usage no npm install needed!

<script type="module">
  import uhooksFx from 'https://cdn.skypack.dev/uhooks-fx';



CSP strict

This module allows reduced/state updates to propagate to an outer hook, avoiding duplicated execution of inner hooks for libraries that have contained updates such as µland.

This module exports same utilities via uhooks-fx/async, which is based on uhooks/async for asynchronous hooks.


const test = ({hooked, dropEffect, useEffect, useState}) => {

  const state = initial => {
    const result = useState(initial);
    useEffect(() => {
      console.log('\x1b[2m', initial, 'fx in', '\x1b[0m');
      return () => {
        console.log('\x1b[2m', initial, 'fx out', '\x1b[0m');
    }, []);
    console.log('\x1b[2m', 'state value:', result[0], '\x1b[0m');
    return result;

  const first = hooked(state);
  const second = hooked(state);

  const parent = hooked(
    () => {
      const [a, $a] = first('a');
      const [b, $b] = second('b');
      // with uhooks inner updates don't propagate
      // so this will be logged only once
      // with uhooks-fx though, inner changes schedule
      // an update for the outer hook, in this case
      // the parent callback, so this will be logged
      // twice, with updated values too
      console.log('', a, b);
      if (a === 'a')
      if (b === 'b')
    // there is an extra argument to flag a hook as parent


  setTimeout(dropEffect, 0, first);
  setTimeout(dropEffect, 0, second);

// verify the difference
setTimeout(test, 100, require('uhooks'));
setTimeout(test, 200, require('uhooks-fx'));