p-filter
v4.1.0
Published
Filter promises concurrently
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p-filter
Filter promises concurrently
Useful when you need to run promise-returning & async functions multiple times with different inputs concurrently and get a filtered down result.
Install
npm install p-filter
Usage
import pFilter from 'p-filter';
import getWeather from 'get-weather'; // Not a real module
const places = [
getCapital('Norway').then(info => info.name),
'Bangkok, Thailand',
'Berlin, Germany',
'Tokyo, Japan',
];
const filterer = async place => {
const weather = await getWeather(place);
return weather.temperature > 30;
};
const result = await pFilter(places, filterer);
console.log(result);
//=> ['Bangkok, Thailand']
API
pFilter(input, filterer, options?)
Returns a Promise
that is fulfilled when all promises in input
and ones returned from filterer
are fulfilled, or rejects if any of the promises reject. The fulfilled value is an Array
of the fulfilled values returned from filterer
in input
order.
input
Type: Iterable<Promise<unknown> | unknown>
Iterated over concurrently in the filterer
function.
filterer(element, index)
Type: Function
The filterer function that decides whether an element should be included into result. Expected to return boolean | Promise<boolean>
.
options
Type: object
See the p-map
options.
concurrency
Type: number
Default: Infinity
Minimum: 1
The number of concurrently pending promises returned by filterer
.
pFilterIterable(iterable, filterer, options?)
Returns an async iterable that iterates over the promises in iterable
and ones returned from filterer
concurrently, calling filterer
for each element.
import {pFilterIterable} from 'p-filter';
import getWeather from 'get-weather'; // Not a real module
async function * getPlaces() {
const name = await getCapital('Norway');
yield name;
yield 'Bangkok, Thailand';
yield 'Berlin, Germany';
yield 'Tokyo, Japan';
}
const places = getPlaces();
const filterer = async place => {
const weather = await getWeather(place);
return weather.temperature > 30;
};
for await (const element of pFilterIterable(places, filterer)) {
console.log(element);
}
//=> ['Bangkok, Thailand']
iterable
Type: Iterable<Promise<unknown> | unknown>
Iterated over concurrently in the filterer
function.
filterer(element, index)
Type: Function
The filterer function that decides whether an element should be included into result. Expected to return boolean | Promise<boolean>
.
options
Type: object
See the p-map
options.
concurrency
Type: number
Default: Infinity
Minimum: 1
The number of concurrently pending promises returned by filterer
.