How to get users id after filter and map
You could also sort your services on the amount. Then you can group them by the providerId and finally map over the providers to get the output you want:
const services = [ { id: 1, providerId: 1, amount: 250000 }, { id: 4, providerId: 3, amount: 280900 }, { id: 6, providerId: 3, amount: 31000 }, { id: 2, providerId: 2, amount: 58600 }, { id: 3, providerId: 1, amount: 13000 }, { id: 5, providerId: 2, amount: 5000 }, { id: 3, providerId: 3, amount: 59900 }, { id: 6, providerId: 3, amount: 9500 } ]
const providers = [ { id: 1, name: 'Netflix' }, { id: 2, name: 'Comcast' }, { id: 3, name: 'Verizon' } ]
let grouped = services
.sort((a,b) => b.amount - a.amount) // sort `desc`
.reduce((r,c) => ((r[c.providerId] = r[c.providerId] || []).push(c), r), {})
let result = providers.map(p => ({name: p.name, user: grouped[p.id][0].id}))
console.log(result)You could also skip the sort above and check the amount and based on that either push or unshift:
const services = [ { id: 1, providerId: 1, amount: 250000 }, { id: 4, providerId: 3, amount: 280900 }, { id: 6, providerId: 3, amount: 31000 }, { id: 2, providerId: 2, amount: 58600 }, { id: 3, providerId: 1, amount: 13000 }, { id: 5, providerId: 2, amount: 5000 }, { id: 3, providerId: 3, amount: 59900 }, { id: 6, providerId: 3, amount: 9500 } ]
const providers = [ { id: 1, name: 'Netflix' }, { id: 2, name: 'Comcast' }, { id: 3, name: 'Verizon' } ]
let groupedById = services.reduce((acc, cur) => {
let k = cur.providerId
acc[k] = acc[k] || []
if(acc[k][0] && acc[k][0].amount > cur.amount) acc[k].push(cur)
else acc[k].unshift(cur)
return acc
}, {})
let result = providers.map(({name, id}) => ({name, user: groupedById[id][0].id}))
console.log(result)This way you only have one Array.reduce and one Array.map which will be more performant than your original version which has forEach, filter and map.