31 lines
995 B
TypeScript
31 lines
995 B
TypeScript
import { useMemo, useReducer } from 'react';
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// Extracts property names from initial state of reducer to allow typesafe dispatch objects
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export type FieldNames<T> = {
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[K in keyof T]: T[K] extends string ? K : K;
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}[keyof T];
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// Returns the Action Type for the dispatch object to be used for typing in things like context
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export type ActionType<T> =
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| { type: 'reset' }
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| { type?: 'change'; field: FieldNames<T>; value: any };
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// Returns a typed dispatch and state
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export const useCreateReducer = <T>({ initialState }: { initialState: T }) => {
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type Action =
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| { type: 'reset' }
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| { type?: 'change'; field: FieldNames<T>; value: any };
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const reducer = (state: T, action: Action) => {
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if (!action.type) return { ...state, [action.field]: action.value };
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if (action.type === 'reset') return initialState;
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throw new Error();
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};
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const [state, dispatch] = useReducer(reducer, initialState);
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return useMemo(() => ({ state, dispatch }), [state, dispatch]);
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};
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