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caasi/set-state-action.ts

Created September 22, 2021 21:49
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set-state-action.ts
type SetStateAction<S> = S | (prevState: S) => S;
export const isStateTransition = <S>(
x: SetStateAction<S>
): x is StateTransition<S> => {
return typeof x === "function";
};
export const tapStateAction = <S>(
s: SetStateAction<S>,
f: (x: S) => void
): SetStateAction<S> => {
if (isStateTransition(s)) {
return (prevState: S) => {
const newState = s(prevState);
f(newState);
return newState;
};
}
f(s);
return s;
};
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