Reactjs 通用类型脚本类型+；反作用钩

我有以下http钩子：

export const useHttp = <T,>(initUrl: string, initData: T) => {
    const [url, setUrl] = useState(initUrl);
    const [state, dispatch] = useReducer(fetchReducer, {
        isLoading: false,
        error: '',
        data: initData
    });

    useEffect(() => {
        let cancelRequest = false;

        const fetchData = async (cancelRequest: boolean = false) => {
            if (!url) return;

            dispatch({ type: 'API_REQUEST'});
            try {
                const responsePromise: AxiosPromise<T> = axios(url);
                const response = await responsePromise;
                if (cancelRequest) return;
                dispatch({ type: 'API_SUCCESS', payload: response.data });
            } catch (e) {
                console.log("Got error", e);
                dispatch({ type: 'API_ERROR', payload: e.message });
            }
        };
        fetchData(cancelRequest);

        return () => {
            cancelRequest = true;
        }

    }, [url]);

    const executeFetch = (url: string) => {
        setUrl(url);
    };

    return { ...state, executeFetch}
};

但我得到：

Type '{ executeFetch: (url: string) => void; error: string; isLoading: boolean; data: unknown; }' is not assignable to type 'HttpReducer<T>'.

类型“{executeFetch:（url:string）=>void；错误：string；isload:boolean；数据：未知；}”不可分配给类型“HttpReducer”。

我能够。您希望

useReducer

钩子能够根据初始状态的类型推断出状态类型，但它只是推断

IState

useReducer

的类型，以便泛型参数是减速器的类型。状态的类型是从带有

ReducerState

实用程序类型的reducer中推断出来的。它不希望有一个通用的减速器，也不能很好地使用它

吊钩的

T

与减速器的

T

之间没有关系，而与状态无关

fetchReducer

是一个通用函数，这意味着它可以获取任何

IState

并返回相同类型的

IState

。我们可以使用这个函数来处理钩子的

IState

，但是为了推断状态的类型，我们需要说我们的函数只接受并返回

IState

您需要将

useReducer

上的泛型设置为：

const [state, dispatch] = useReducer<(state: IState<T>, action: TAction<T>) => IState<T>>( ...

我们需要该功能的特定用例：

export const useHttp = <Data,>(initUrl: string, initData: Data) => {
  const [url, setUrl] = useState(initUrl);
  const [state, dispatch] = useReducer<<T,>(state: IState<T>, action: TAction<T>) => IState<T>>(fetchReducer, {

export const useHttp = <Data,>(initUrl: string, initData: Data) => {
  const [url, setUrl] = useState(initUrl);
  const [state, dispatch] = useReducer<(state: IState<Data>, action: TAction<Data>) => IState<Data>>(fetchReducer, {

export const useHttp=（initUrl:string，initData:Data）=>{
const[url，setUrl]=useState（initUrl）；
const[state，dispatch]=useReducer-IState>（fetchReducer{

当我们知道我们的减速器状态类型是

IState

，那么我们就知道

data

的类型是

data

现在调用

useHttp（）

将提供类型为

IArticle[]

的

data

变量

---

尝试将类型添加到

状态

。或将返回类型添加到自定义挂钩。将类型添加到

状态

是什么意思？我的状态参数具有

IState

类型。问题中没有提到这一点……您是否尝试添加返回类型？如何键入

fetchReducer

。@Rameshredy不确定如何添加su我的案例的ch类型。用示例更新了我的问题

Type '{ executeFetch: (url: string) => void; error: string; isLoading: boolean; data: unknown; }' is not assignable to type 'HttpReducer<T>'.

const [state, dispatch] = useReducer<(state: IState<T>, action: TAction<T>) => IState<T>>( ...

const [state, dispatch] = useReducer<<T,>(state: IState<T>, action: TAction<T>) => IState<T>>(...

export const useHttp = <Data,>(initUrl: string, initData: Data) => {
  const [url, setUrl] = useState(initUrl);
  const [state, dispatch] = useReducer<<T,>(state: IState<T>, action: TAction<T>) => IState<T>>(fetchReducer, {

export const useHttp = <Data,>(initUrl: string, initData: Data) => {
  const [url, setUrl] = useState(initUrl);
  const [state, dispatch] = useReducer<(state: IState<Data>, action: TAction<Data>) => IState<Data>>(fetchReducer, {