sum values in an array based on another array

Question

I am currently trying to sum some values in an array of objects, based on the Id of another array present in the current array. assuming I have this array

const queryArray = [ "1" , "2" ]

and this is the array I would like to sum if fees property values of the Id matches

const services = [
  {
    Id: "1",
    services: "Early Check-In",
    fees: "7500"
  },
  {
    Id: "2",
    services: "Late Checkout",
    fees: "7500"
  },
  {
    Id: "3",
    services: "Airport Chauffeur",
    fees: "25000"
  }
]

so I will like to get the sum of the fees property value in the services array up here based on the Id available in the queryArray. so in this case

[ "1" , "2" ]

should return

if I decided to use this below

[ "1" , "3" ]

it should return

and if also do

[ "1", "2" , "3"]

it should return

Am new to javascript so I can't even think of any possible solution or the step to take at all.

Alberto · Accepted Answer · 2021-10-15 20:52:55Z

5

Sure, filter the services you need -> map service to it's value -> reduce the resulting list to a singe number adding the elements:

const services = [
  {
    Id: "1",
    services: "Early Check-In",
    fees: "7500"
  },
  {
    Id: "2",
    services: "Late Checkout",
    fees: "7500"
  },
  {
    Id: "3",
    services: "Airport Chauffeur",
    fees: "25000"
  }
]
const ids = ["1" , "2"]

console.log(
  services
    .filter(({Id}) => ids.includes(Id))
    .map(({fees}) => parseFloat(fees))
    .reduce((acc, fees) => acc + fees, 0)
  
)

edited Oct 15, 2021 at 20:52

answered Oct 15, 2021 at 19:55

Alberto

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4 Comments

Temitayo Over a year ago

thank you it works as expected, I just hope I will also have pieces of knowledge like this in the future. Thanks once again

Alberto Over a year ago

@Temitayo sure, the best thing on JS array is that you can do some "functional" things with them, and so you can literally think what you want to do step by step

Temitayo Over a year ago

can you please provide a fix of the code if the array is empty, the reducer keeps flagging error if array is empty

Alberto Over a year ago

@Temitayo as Scotta said, you can add , 0 to the reducer parameter to use that as initial value, i'll fix the code immediatly

Spectric · Accepted Answer · 2021-10-15 20:03:09Z

1

Check whether the id is included in the id array inside the reducer:

const services = [
  {
    Id: "1",
    services: "Early Check-In",
    fees: "7500"
  },
  {
    Id: "2",
    services: "Late Checkout",
    fees: "7500"
  },
  {
    Id: "3",
    services: "Airport Chauffeur",
    fees: "25000"
  }
]

const queryArray = [ "1" , "2" ]

const res = services.reduce((a,b) => queryArray.includes(b.Id) ? a += +b.fees : a, 0)

console.log(res)

answered Oct 15, 2021 at 20:03

Spectric

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Comments

The fourth bird · Accepted Answer · 2021-10-15 20:09:11Z

1

You could also use reduce, and for every entry check if the Id of the current value is in the queryArray. If it is, then return the current total plus the current fees.

Set a 0 as the start value.

const services = [{
    Id: "1",
    services: "Early Check-In",
    fees: "7500"
  },
  {
    Id: "2",
    services: "Late Checkout",
    fees: "7500"
  },
  {
    Id: "3",
    services: "Airport Chauffeur",
    fees: "25000"
  }
]

const queryArray = ["1", "2"]

let res = services.reduce(
  (total, curr) => queryArray.includes(curr.Id) ? total + parseInt(curr.fees, 10) : total,
  0
);
console.log(res);

edited Oct 15, 2021 at 20:09

answered Oct 15, 2021 at 20:03

The fourth bird

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