如何在打字稿中正确使用泛型？

Question

I get stuck with generics . How can I correctly use generics in my case :

export const getEuropeLocations = async (
  apiKey: string
): Promise<Location> => {
  let response = await axios({
    method: "get",
    url: `${apiBaseUrl}europe/`,
    headers: {
      Authorization: `Bearer ${apiKey}`,
    },
  });
  return response.data as Location; // how to return generic here ? 
};

Answer 1

Axios has typings for this. It lets you specify a generic type for the axios functions so that result.data will have that generic type.

For example, you can do this:

import axios from "axios";

export const getEuropeLocations = async (
  apiKey: string
) => {
  let response = await axios.get<Location>({
    method: "get",
    url: `${apiBaseUrl}europe/`,
    headers: {
      Authorization: `Bearer ${apiKey}`,
    },
  });
  return response.data;
};

If you want to make the entire function generic, you can do this:

export const getEuropeLocations = async <T>(
  apiKey: string
) => {
  let response = await axios.get<T>({
    method: "get",
    url: `${apiBaseUrl}europe/`,
    headers: {
      Authorization: `Bearer ${apiKey}`,
    },
  });
  return response.data;
};