Sort and manipulate array in javascript

Question

I have the following array:

var curr = [{ "Year": 2019, "Title": "Asset Management Sample", "Sum": 1020000.0, "Budget":0

}, {
  "Year": 2019,
  "Title": "Monday test 2",
  "Sum": 2546658.0,
  "Budget":100
}, {
  "Year": 2020,
  "Title": "Asset Management Sample",
  "Sum": 1020000.0,
  "Budget":1000
}, {
  "Year": 2020,
  "Title": "Monday test 2",
  "Sum": 3472000.0,
  "Budget":100
}, {
  "Year": 2021,
  "Title": "Asset Management Sample",
  "Sum": 1020000.0,
  "Budget":100
}, {
  "Year": 2021,
  "Title": "Monday test 2",
  "Sum": 2452000.0,
  "Budget":100
}]

That I need to change to:

[{
  "Year": 2019,
  "Asset Management Sample": 1020000.0,
  "Monday test": 2546658.0
}, {
  "Year": 2020,
  "Asset Management Sample": 1020000.0,
  "Monday test 2": 3472000.0
}, {
  "Year": 2021,
  "Asset Management Sample": 1020000.0,
  "Monday test 2": 2452000.0
}]

With help from earlier posters I have used .reduce (slightly modified from below) to generate this:

      var res = arr.reduce(function(acc, curr) {
      acc[curr.Year] = acc[curr.Year];
      acc[curr.Year] = acc[curr.Year] || { Year: curr.Year } ;
      acc[curr.Year][curr.Title] = curr.Sum;

      return acc;

I need to expand this to include a sum of all the budget values for each year (there should be a single budget value per year). I added the following line in before the return:

acc[curr.Year][curr.Budget] = curr[curr.Budget] || { Budget: curr.Budget } ;

It is adding individual entries for each Budget value. How do I sum the Budget values and return it without affecting the other returned array?

Please show your code. Also, there is no groupBy in JavaScript. — str
– str, Commented May 28, 2019 at 8:35
Check for answer here: stackoverflow.com/questions/1129216/… — mjanisz1
– mjanisz1, Commented May 28, 2019 at 8:35
possible duplicate of stackoverflow.com/questions/39302871/… — AsukaSong
– AsukaSong, Commented May 28, 2019 at 8:35

Jack Bashford · Accepted Answer · 2019-05-28 08:55:22Z

2

Use reduce like so:

const arr = [{"Year":2019,"Title":"Asset Management Sample","Sum":1020000},{"Year":2019,"Title":"Monday test 2","Sum":2546658},{"Year":2020,"Title":"Asset Management Sample","Sum":1020000},{"Year":2020,"Title":"Monday test 2","Sum":3472000},{"Year":2021,"Title":"Asset Management Sample","Sum":1020000},{"Year":2021,"Title":"Monday test 2","Sum":2452000}];
const res = Object.values(arr.reduce((acc, { Year, Title, Sum }) => (acc[Year] = acc[Year] || { Year }, acc[Year][Title] = Sum, acc), {}));
console.log(res);

More verbose version:

const arr = [{"Year":2019,"Title":"Asset Management Sample","Sum":1020000},{"Year":2019,"Title":"Monday test 2","Sum":2546658},{"Year":2020,"Title":"Asset Management Sample","Sum":1020000},{"Year":2020,"Title":"Monday test 2","Sum":3472000},{"Year":2021,"Title":"Asset Management Sample","Sum":1020000},{"Year":2021,"Title":"Monday test 2","Sum":2452000}];
const res = Object.values(arr.reduce((acc, { Year, Title, Sum }) => {
  acc[Year] = acc[Year] || { Year };
  acc[Year][Title] = Sum;
  return acc;
}, {}));
console.log(res);

.as-console-wrapper { max-height: 100% !important; top: auto; }

ES5 syntax:

var arr = [{"Year":2019,"Title":"Asset Management Sample","Sum":1020000},{"Year":2019,"Title":"Monday test 2","Sum":2546658},{"Year":2020,"Title":"Asset Management Sample","Sum":1020000},{"Year":2020,"Title":"Monday test 2","Sum":3472000},{"Year":2021,"Title":"Asset Management Sample","Sum":1020000},{"Year":2021,"Title":"Monday test 2","Sum":2452000}];
var res = arr.reduce(function(acc, curr) {
  acc[curr.Year] = acc[curr.Year] || { Year: curr.Year };
  acc[curr.Year][curr.Title] = curr.Sum;
  return acc;
}, {});
res = Object.keys(res).map(function(key) {
  return res[key];
});
console.log(res);

.as-console-wrapper { max-height: 100% !important; top: auto; }

edited May 28, 2019 at 8:55

answered May 28, 2019 at 8:38

Jack Bashford

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7 Comments

adiga Over a year ago

It's okay to use semicolons, new lines and return. This is not code-golf :) It'll be very hard for the OP to understand what's going on here

Jack Bashford Over a year ago

My bad @adiga :) I'll add a more verbose version.

Jack Bashford Over a year ago

Edited @adiga is that understandable :D

adiga Over a year ago

Object.values() is ES2016+ (Not even 2015)

Jack Bashford Over a year ago

Welp, missed that.

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