Can't perform a React state update on an unmounted component
useEffect(() => {
let isMounted = true; // note mutable flag
someAsyncOperation().then(data => {
if (isMounted) setState(data); // add conditional check
})
return () => { isMounted = false }; // cleanup toggles value, if unmounted
}, []); // adjust dependencies to your needsCan't perform a React state update on an unmounted component
export default function MyComponent() {
const [loading, setLoading] = useState(false);
const [someData, setSomeData] = useState({});
let componentMounted = true; // (3) component is mounted
// ...
useEffect(() => {
setLoading(true);
someResponse = await doVeryLongRequest(); // it needs some time
// When request is finished:
if (componentMounted){ // (5) is component still mounted?
setSomeData(someResponse.data); // (1) write data to state
setLoading(false); // (2) write some value to state
}
return () => { // This code runs when component is unmounted
componentMounted = false; // (4) set it to false if we leave the page
}
}, []);
return (
<div className={loading ? "loading" : ""}>
{someData}
<a href="SOME_LOCAL_LINK">Go away from here!</a>
</div>
);
}Copyright © 2021 Codeinu
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