RSVP lib has a hash of promises helper that allows to "retrieve" promises references:
var promises = {
posts: getJSON("/posts.json"),
users: getJSON("/users.json")
};
RSVP.hash(promises).then(function(results) {
console.log(results.users) // print the users.json results
console.log(results.posts) // print the posts.json results
});
Is there a way to do such a thing with vanilla promises (in modern ES)?
It's not hard to implement.
async function hash(promiseObj) {
// Deconstitute promiseObj to keys and promises
const keys = [];
const promises = [];
Object.keys(promiseObj).forEach(k => {
keys.push(k);
promises.push(promiseObj[k]);
});
// Wait for all promises
const resolutions = await Promise.all(promises);
// Reconstitute a resolutions object
const result = {};
keys.forEach((key, index) => (result[key] = resolutions[index]));
return result;
}
hash({
foo: Promise.resolve(8),
bar: Promise.resolve(16),
}).then(results => console.log(results));