I came across this code recently and I'm curious about why it specifies the return type as Promise. Since the function is returning data, which is an object, what's the purpose of adding | null at the end?
const getSomething = async (
id: string
): Promise<UserData | null> => {
try {
const { data } = await axios.get(
`${API}/user?id=${id}`
);
return data;
} catch (err) {
if (err.response) {
return err.response.data;
}
return null;
}
};
Asynchronous functions always yield Promises, allowing for the use of the await keyword to wait for their completion inside the function before proceeding with the result outside of it.
In this scenario, the function getSomething attempts to fetch data from an axios call. If the call is successful, the data is straightforwardly returned:
return data;
However, if the call fails, the function will return one of the following outcomes:
if (err.response) {
return err.response.data;
}
return null;
If the axios call encounters an error and there is no err.response property available, then the function will return null. Including | null ensures that the getSomething function is correctly typed.
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