Retry multiple fetch - fetch

Question

How do I retry this fetch x times if it fails?
The code is based on this article: https://dmitripavlutin.com/javascript-fetch-async-await/
async function fetchData() {
const [firstResponse, secondResponse] = await Promise.all([
fetch(firstUrl),
fetch(secondUrl),
]);
const first = await firstResponse.json();
const second = await secondResponse.json();
return [first, second];
}
fetchData()
.then(([first, second]) => {
console.log("success");
})
.catch((error) => {
console.log("error");
});

Answer 1

Since the requests are independent of each other, I'd have a utility function that will retry X times and then use that in the Promise.all. I'd also have a utility function for fetching JSON that handles the fetch API footgun where it doesn't check HTTP success (see my blog post here). So something along these lines:
// Fetch JSON
function fetchJSON(...args) {
const response = await fetch(...args);
if (!response.ok) {
throw new Error(`HTTP error ${response.status}`);
}
return response.json();
}
// Fetch JSON with up to `retries` retries
async fetchJSONWithRetry(retries, ...args) {
while (retries > 0) {
try {
const result = await fetchJSON(...args);
return result;
} catch (e) {
if (--retries === 0) {
throw e;
}
}
}
}
// Your `fetchData`
async function fetchData(retries = 5) {
const [first, second] = await Promise.all([
fetchJSONWithRetry(retries, firstUrl),
fetchJSONWithRetry(retries, secondUrl),
]);
return [first, second];
}