Question

Here is my useSend function, I am working with Typescript + React.

const useSend = (method: string, url: string, data: any): Promise<string> => {
    return fetch(url, {
        method: method,
        headers: { 
            "Content-Type": "application/json",
            "Accept": "application/json", },
        credentials:  include ,
        body: JSON.stringify(data),
    })
    .then((response) => {  
        if (response.status === 200) {
            return "success";
        } else {
            response.json()
            .then((resp) => {
                return resp;
            })
        }
    })
    .catch(err => {
        console.log(err)
        return err;
    });
}
 
export default useSend;

When I call .then on useSend, an error is always thrown : Cannot read properties of undefined (reading then ) TypeError: Cannot read properties of undefined (reading then )

function useSubmit (event: React.FormEvent<HTMLFormElement>) {
    event.preventDefault();
    const form = new FormData(event.currentTarget);
    const data = { email: form.get( email ), password: form.get( password ) };
    
    useSend("POST", "http://localhost:2999/login", data)
        .then((temp: string) => {
            console.log(temp);
            result = temp;
            if (result == "success") {
                window.location.href = "/feed/latest";
        }
    })
}

我对返回声明和封锁结构做了改动,但没有任何帮助,我能否帮助解释为什么这一职务被退回,哪怕是我曾经在每一步骤中利用过,以便在承诺得到解决后恢复外部职能?

Answer 1

首先,你点名的是<代码>不适用(<>>>>/代码>,不是重读。更不用说把这一职能重新命名为其他职能。

其次,在<代码>response.json(......)前,你没有<代码>return,因此,你没有再回升价值。

第三,如果你提供全方位的痕迹,而不仅仅是错误的信息,将是有益的。全部脚印应当表明该法典的错误来自该法典。

[Edit] 第四,正如@Pac0在其评论中建议的那样,请提供实际上称作useSend(<>”的代码,因为该代码正从该错误中删除。

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