使用 Typescript 的 Redux reducer 初始状态

Question

我想用 typescript 创建一个 reducer！

paymentReducer.tsx

let initialState = {
    saved: [],
};

export interface Payment {
    saved: ISavedPayment[];
}

export let payment = (
    state = initialState,
    { type, payload }: PaymentActions
): Payment => {
    switch (type) {
        case SAVED_PAYMENTS_LOADED:
            return { ...state, saved: payload };
        default:
            return state;
    }
};

没有错误！但是reducer的state参数中saved数组的类型变成了never。但应该是ISavedPayment[]？

(parameter) state: { saved: never[]; }

Answer 1

明确指定 initialState 的类型：

const initialState: { saved: ISavedPayment[] } = {
    saved: [],
};

另见：

• What is "not assignable to parameter of type never" error in typescript?
• TypeScript: Creating an empty typed container array
• [] is regard wrong as never[] when strictNullChecks is true #13140