values get undefined after then of promise nodejs - node.js

Question

I'm facing a problem with my code... I make a query to my DB to check if a mac address of a array of macs is on the DB. If I have any result I return the count of macs in my DB and if is > 0 then I don't add nothing cause the mac already is listed, but if my result.count = 0 then I will add a new record.
My new record just have the mac address. For this I'm trying:
var countRepetidos = 0
var countPromises = []
if (obj.data.list != {} && obj.data.list.length > 0) {
var aux = obj.data["list"]
countRepetidos = 0
for (var i = 0; i < aux.length; i++) {
countPromises.push(Database.Probing.getMacAdress(aux[i]).then(function(data) {
console.log("probing countPromises aux[i] ", aux[i])
if (data.count > 0) {
countRepetidos += 1
} else {
Database.Probing.addMac(aux[i])
}
return Promise.resolve()
}))
}
Promise.all(countPromises).then(() => {
dataRepeated = [obj.data.stats.since, countRepetidos]
listaRepeated.push(dataRepeated)
console.log("probing listaRepeated --> ", listaRepeated)
if (listaRepeated != [] && (listaRepeated[0][0] != undefined && listaRepeated[0][1] != undefined)) {
Database.Probing.getLastTimestamp("probing_repeated", device.id).then(function(data) {
var lastTimestamp = data.date_part
console.log('probing lastTimestamp ', lastTimestamp * 1000)
if (lastTimestamp != listaRepeated[0][0] / 1000) {
Controllers.Agregate.agregateData("probing_repeated", 5 * 60, listaRepeated, dbHistConnectionString, device.id, device.network_id, device.organization_id, ["time", "clients"])
}
})
}
})
}
The problem is after the then of Database.Probing.getMacAddress my aux[i] gets undefined and I need this value to insert into my DB.
Anyone can help?

Answer 1

You need to preserve the value of i. You can do this way:
for (var i = 0; i < aux.length; i++) {
(function(i) {
countPromises.push(
Database.Probing.getMacAdress(aux[i]).then(function(data) {
console.log("probing countPromises aux[i] ", aux[i])
if (data.count > 0) {
countRepetidos += 1
} else {
Database.Probing.addMac(aux[i])
}
return Promise.resolve()
}))
})(i)
}
Edit 1: As suggested by #lain, use let over var
for (let i = 0; i < aux.length; i++) {}