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, May 28 '19 at 08:35
Check for answer here: https://stackoverflow.com/questions/1129216/sort-array-of-objects-by-string-property-value — mjanisz1, May 28 '19 at 08:35
possible duplicate of https://stackoverflow.com/questions/39302871/filter-and-sort-a-javascript-array — AsukaSong, May 28 '19 at 08:35

Jack Bashford · Accepted Answer · 2019-05-28T08:55:22.480

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; }

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 — adiga, May 28 '19 at 08:49
The ES5 syntax worked perfectly, the reduce version gave me an error, is that due to the platform I am working on? — Mondo, May 28 '19 at 10:41
Most likely @Mondo - it's working for me in the above snippet. — Jack Bashford, May 28 '19 at 10:43

Sort and manipulate array in javascript

1 Answers1