21 lines
630 B
JavaScript
21 lines
630 B
JavaScript
import { isPromise } from './isPromise.mjs';
|
|
|
|
/**
|
|
* Similar to Array.prototype.reduce(), however the reducing callback may return
|
|
* a Promise, in which case reduction will continue after each promise resolves.
|
|
*
|
|
* If the callback does not return a Promise, then this function will also not
|
|
* return a Promise.
|
|
*/
|
|
export function promiseReduce(values, callbackFn, initialValue) {
|
|
let accumulator = initialValue;
|
|
|
|
for (const value of values) {
|
|
accumulator = isPromise(accumulator)
|
|
? accumulator.then((resolved) => callbackFn(resolved, value))
|
|
: callbackFn(accumulator, value);
|
|
}
|
|
|
|
return accumulator;
|
|
}
|