Sum all data in array of objects into new array of

Question

I have an array of objects that looks like this:

var data = [{costOfAirtickets: 2500, costOfHotel: 1200},{costOfAirtickets: 1500, costOfHotel: 1000}]

and I want to sum each element in the array to produce an array like this:

var result = [{costOfAirtickets: 4000, costOfHotel: 2200}]

I have used a map and reduce function but I was able to only sum an individual element like so:

data.map(item => ite.costOfAirtickets).reduce((prev, next)=>prev + next); // 22

At the moment this produces a single value which is not what I want as per initial explanation.

Is there a way to do this in Javascript or probably with lodash.

Answer 1

You can use a simple forEach() loop for that:

var data = [{costOfAirtickets: 2500, costOfHotel: 1200},{costOfAirtickets: 1500, costOfHotel: 1000}];
var res = [];
var tempObj = {};
data.forEach(({costOfAirtickets, costOfHotel}) => {
  tempObj['costOfAirtickets'] = (tempObj['costOfAirtickets'] || 0) + costOfAirtickets;
  tempObj['costOfHotel'] = (tempObj['costOfHotel'] || 0) + costOfHotel;
 });
res.push(tempObj);
console.log(res);

Answer 2

Using for..in to iterate object and reduce to iterate array

var data = [{costOfAirtickets: 2500, costOfHotel: 1200},{costOfAirtickets: 1500, costOfHotel: 1000}];

var result = [data.reduce((acc, n) => {
  for (var prop in n) {
    if (acc.hasOwnProperty(prop)) acc[prop] += n[prop];
    else acc[prop] = n[prop];
  }
  return acc;
}, {})]
console.log(result)