readme.md

React Suspense utils

$ npm i -D @cprecioso/react-suspense       # if you use npm
$ yarn add --dev @cprecioso/react-suspense # if you use yarn

API

See the docs

Quick-start

A simple way to do a fetch while suspending the tree

import { bindKeyedSuspense } from "@cprecioso/react-suspense";

const { suspend: fetchPokemon } = bindKeyedSuspense((name: string) =>
  fetch(`https://pokeapi.co/api/v2/pokemon/${name}`).then((res) => res.json()),
);

const Pokemon = ({ name }: { name: string }) => {
  const data = fetchPokemon(name);
  return (
    <li>
      {data.name} is {data.height * 10}cm tall
    </li>
  );
};

const App = () => {
  const names = ["pichu", "pikachu", "raichu"];

  return (
    <ul>
      {names.map((name) => (
        <Pokemon key={name} name={name} />
      ))}
    </ul>
  );
};

export default App;

You can wrap these components in Suspenses, handle data fetching errors in your regular error boundaries, and use useDeferredValue and startTransition to defer the loading to the background.

Guide

This library returns some functions named suspend. suspend() can be called from inside a component or a hook, and inside conditionals or loops, but not from other kinds of functions such as useEffect or code outside of a React tree.

The following functions are ordered from simple to more advanced:

bindSuspense

import { bindSuspense } from "@cprecioso/react-suspense";

const appConfig = bindSuspense(() =>
  fetch("/api/config").then((res) => res.json()),
);

export const Greeting = () => {
  const { accentColor } = appConfig.suspend();
  return <h1 style={{ color: accentColor }}>Hello world</h1>;
};

Pass it an async function, returns an object with:

• suspend(): call it to suspend your tree while the async function resolves.

• cache: an object that provides a get/set function to manually manipulate the cache. Useful to call cache.set(null) and force re-fetching.

bindKeyedSuspense

import { bindKeyedSuspense } from "@cprecioso/react-suspense";

const userInfo = bindKeyedSuspense((userId) =>
  fetch(`/api/user/${userId}`).then((res) => res.json()),
);

export const UserInfo = ({ userId }) => {
  const { name } = userInfo.suspend(userId);
  return <p>Name: {name}</p>;
};

Pass it an async function, returns an object with:

• suspend(key): call it to suspend your tree while the async function resolves.

• cache: an object that provides a get/set function to manually manipulate the cache. Useful to call cache.set(key, null) and force re-fetching.

createSuspense

createKeyedSuspense

Same as their bind counterparts. However, the async function is not passed when creating the cache, but when calling suspend: suspend(fn) / suspend(key, fn).

Custom Storage

All functions also accept an object as their last parameter, with the option storage. You can provide a backend for the cache, useful for using an LRU cache (quick-lru), avoiding holding references to the obejcts (WeakMap), or accepting multiple objects as the key (many-keys-map).

The object must implement get and set methods like those of Map.