键入Promisse的结果

Question

可以避免这种类型：

(await getCryptocurrencyMap(1, 5)) as Cryptocurrency[]

并在getCryptocurrencyMap上返回类型？

完整代码：

type Cryptocurrency = {
    id: number
    symbol: string
    name: string
}

const getCryptocurrencyMap = (start: number, limit: number) =>
  new Promise(async (resolve, reject) => {
    try {
      const response = await axios.get(`${BASE_URL}/v1/cryptocurrency/map`, {
        params: { start, limit },
        headers: {
          'X-CMC_PRO_API_KEY': COINMARKETCAP_APIKEY,
        },
      })

      resolve(response.data.data)
    } catch (error) {
      reject(error)
    }
  })

export const getCryptocurrencies = async () => {
  const arr = (await getCryptocurrencyMap(1, 5)) as Cryptocurrency[]

  return arr.map(({symbol, name}) => ({ [symbol]: name }))
}

Answer 1

是的-使用仿制药：

new Promise<Cryptocurrency[]>((resolve, reject) => {
   // resolve can only be used with `Cryptocurrency[]` now
});

但是，new Promise包装器在这里似乎是多余的。只需返回axios响应，这也允许泛型：

const result = await axios.get<Cryptocurrency[]>(url, opts);
const currencies = result.currencies; // data is Cryptocurrency[] 

请注意，这是纯类型记录运行时强制转换。它不能保证API的实际返回结果是指定类型的。