use-transition-effect
Run long effects without blocking the main thread
Motivation
Let's say you want to render something complex on a canvas in a React application.
Canvas API is imperative, so to interact with it, you need to use the useEffect()
hook.
Unfortunately, if rendering takes too long, you can block the main thread and make your
application unresponsive (especially on low-end devices).
The useTransitionEffect()
hook provides a way to split long-running effects into smaller chunks
to unblock the main thread. It uses scheduler package (from React)
to schedule smaller units of work and coordinate it with React rendering.
Installation
This package requires React 17+ and scheduler 0.20+
npm install use-transition-effect
yarn add use-transition-effect
Usage
const [
isPending,
startTransitionEffect,
stopTransitionEffect,
] = useTransitionEffect();
The API is very similar to the useTransition
hook from React.
It returns a stateful value for the pending state of the transition effect, a function to start it, and a function to stop it.
startTransitionEffect
lets you schedule a long-running effect without blocking the main thread. It expects a generator
function as an argument, so you can yield to unblock the main thread. The generator function receives the shouldYield
function,
which returns true if the current task takes too long:
startTransitionEffect(function*(shouldYield) {
for (let item of items) {
doSomeComplexSideEffects(item);
if (shouldYield()) {
yield;
}
}
});
Additionally, you can yield and return a cleanup function that will run on transition stop (including unmount):
startTransitionEffect(function*(shouldYield) {
const cleanup = () => cleanupSideEffects();
for (let item of items) {
doSomeComplexSideEffects(item);
if (shouldYield()) {
yield cleanup;
}
}
return cleanup;
});
stopTransitionEffect
lets you stop the current long-running effect. You can use it as a useEffect
cleanup:
useEffect(() => {
startTransitionEffect(function*() {
});
return () => stopTransitionEffect();
}, []);
isPending
indicates when a transition effect is active to show a pending state:
function App() {
const [
isPending,
startTransitionEffect,
stopTransitionEffect,
] = useTransitionEffect();
function handleStartClick() {
startTransitionEffect(function*() {
});
}
function handleStopClick() {
stopTransitionEffect();
}
return (
<div>
{isPending && <Spinner />}
<button onClick={handleStartClick} disabled={isPending}>
Start
</button>
<button onClick={handleStopClick} disabled={!isPending}>
Stop
</button>
</div>
);
}
License
MIT