Seem to be having some issues incorporating async/await with .reduce(), like so:
const data = await bodies.reduce(async(accum, current, index) => { const methodName = methods[index] const method = this[methodName] if (methodName == 'foo') { current.cover = await this.store(current.cover, id) console.log(current) return { ...accum, ...current } } return { ...accum, ...method(current.data) } }, {}) console.log(data)
The data
object is logged before the this.store
completes…
I know you can utilise Promise.all
with async loops, but does that apply to .reduce()
?
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Answer
The problem is that your accumulator values are promises – they’re return values of async function
s. To get sequential evaluation (and all but the last iteration to be awaited at all), you need to use
const data = await array.reduce(async (accumP, current, index) => { const accum = await accumP; … }, Promise.resolve(…));
That said, for async
/await
I would in general recommend to use plain loops instead of array iteration methods, they’re more performant and often simpler.