Reduce a list of values using promises into a promise for a value
npm install p-reduce> 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.
``
$ npm install p-reduce
`js
import pReduce from 'p-reduce';
import humanInfo from 'human-info'; // Not a real module
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.
#### input
Type: Iterable
Iterated over serially in the reducer function.
#### reducer(previousValue, currentValue, index)
Type: Function
Expected to return a value. If a Promise is returned, it's awaited before continuing with the next iteration.
#### initialValue
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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