Sometimes I want to resolve several promises at once, then do something when they’re all done. For example, make several API calls, then do something with all the results.
I was doing something like this before:
// Build your promises array
let promises = [
fetch('https://blah.com/static/file.json'),
fetch('https://blah.com/api/thing/one'),
fetch('https://blah.com/apr/thing/two'),
]
Promise.all(promises.map((p) => p.catch((err) => err)))
.then(([file, thing1, thing2]) => {
console.log(file)
console.log(thing1)
console.log(thing2)
})
.catch((err) => {
console.error({ err })
})A simpler, neater & easier to read version uses Promise.allSettled(promises) to do the same thing:
// Build your promises array
let promises = [
fetch('https://blah.com/static/file.json'),
fetch('https://blah.com/api/thing/one'),
fetch('https://blah.com/apr/thing/two'),
]
// Resolve all the promises
Promise.allSettled(promises)
.then(([file, thing1, thing2]) => {
// Each promise in the original array is now a response object:
// For each outcome object, a status string is present. If the status is fulfilled, then a value is present.
// If the status is rejected, then a reason is present.
// The value (or reason) reflects what value each promise was fulfilled (or rejected) with.
console.log(file)
console.log(thing1)
console.log(thing2)
})
.catch((err) => {
console.error({ err })
})