I have this code that is a simple implementation of async/await while doing ajax call
export const getExternalResource = async (): Promise|String|null => {
return new Promise(async (resolve, reject) =>{
const response = await fetch(url);
const json = response.json();
if(json) {
resolve(json);
} else {
resolve(null)
}
});
};
/**
* @var resource will be null|string
*/
const resource = await getExternalResource();
My question is what is the correct return type for the getExternalResource() function?
In code it returns a promise, however when calling the function with await keyword, it returns a basic data type (string|null).
You dont need a fetch inside a Promise since fetch returns a promise. Also return type of an async function or method must be the global Promise type. So changed the return type here to Promise<any>. You can replace any with the matching type
export const getExternalResource = async(url: string): Promise<any> => {
return await fetch(url).then(response => response.json());
};
const resource = getExternalResource('url').then(d=>d);