Reduce a list of values using promises into a promise for a value
Useful when you need to calculate some accumulated value based on async resources.
Please don't use it to write unreadable code.
npm install p-reduce
import pReduce from 'p-reduce';
import humanInfo from 'human-info'; // Not a real package
const names = [
getUser('sindresorhus').then(info => info.name),
'Addy Osmani',
'Pascal Hartig',
'Stephen Sawchuk'
];
const totalAge = await pReduce(names, async (total, name) => {
const info = await humanInfo(name);
return total + info.age;
}, 0);
console.log(totalAge);
//=> 125
Returns a Promise
that is fulfilled when all promises in input
and ones returned from reducer
are fulfilled, or rejects if any of the promises reject. The fulfilled value is the result of the reduction.
Type: Iterable<Promise|any>
Iterated over serially in the reducer
function.
Type: Function
Expected to return a value. If a Promise
is returned, it's awaited before continuing with the next iteration.
Type: unknown
Value to use as previousValue
in the first reducer
invocation.
- p-each-series - Iterate over promises serially
- p-map-series - Map over promises serially
- p-map - Map over promises concurrently
- More…
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