Promise Series: run an async fn in series an arbitrary number of times

promise-series

const _ = require('lodash');

function series(count, asyncFn) {
	return _.range(0, count)
		.reduce((lastRun_, i) => {
			return lastRun_.then(() => asyncFn(i))
		}, Promise.resolve());
}

series(10, (i) => {
	console.log(i);
	return new Promise(resolve => setTimeout(resolve, 500))
})
	.then(() => console.log('done'), err => console.error(err));

I'm using this to "clear out" process.nextTick in tests

function clearTicks(tickCount) {
  return series(tickCount, () => new Promise(resolve => process.nextTick(resolve)));
}

Or...

function clearTicks(tickCount) {
    return _.range(0, tickCount)
        .reduce(lastTick_ => {
            return lastTick_.then(new Promise(process.nextTick))
        }, Promise.resolve());
}