I have a function similar to the code below - it makes a fetch, does things when the call is successful or not, and returns a promise to be handled downstream:
const myFunc = (): Response => {
return fetch('http://something')
.then(r => {
console.log('the call went through, the return code does not matter')
return r
})
.catch(err => {
console.error(`ah crap, the call failed completely: ${err}`)
// and here I do not know how to return a new Response
}
}
}
myFunc().then(r => {
console.log('do something once myFunc is over')
})
My intention is to run some code once myFunc is done, but I need to account for the case the call completely fails (no DNS resolution, rejected call, ...). For that I need to create and return in the catch() a Response promise with, for instance, a forced 503 return code (which is not really correct because the server did not even answer, but anyway).
My question: how can I create such a Response promise?
I would encourage you not to turn a network failure into an apparent HTTP failure (503), but since you've specifically asked how to do that, you can do that by building your own Response object:
const myFunc = (): Response => {
return fetch("http://something")
.catch(err => {
console.error(`the call failed completely: ${err}`)
return new Response(null, {
status: 503,
statusText: "Fake 503",
});
});
};
or if you want to use an async function:
const myFunc = async (): Response => {
try {
return await fetch("http://something");
} catch (err) {
console.error(`the call failed completely: ${err}`)
return new Response(null, {
status: 503,
statusText: "Fake 503",
});
}
};
(Note that there's no need for your .then in the first one (unless you want to do the console.log).)
But, I would strongly encourage you not to do that. Instead, handle this at the point of the call, via a .finally handler (or a try/finally block in an async function).