JavaScript: Sort array of objects by computed property or by an existing property if equal

Question

[
    { name: 'Joe', scores: [1, 2, 3] },
    { name: 'Jane', scores: [1, 2, 3] },
    { name: 'John', scores: [1, 2, 3] }
]

how do I make a function that sorts the elements first by the sum in scores and later by name?

using the index of the list to get into the first aray and then tried to applya an index — nikstreat, Feb 27 '22 at 17:29
and then i tried two for loops one to select the first aray and then get in the second — nikstreat, Feb 27 '22 at 17:30
@nikstreat You will be able to get much better answers on here if you include the code that you tried to get working :) — Jack Gore, Feb 27 '22 at 17:30
when i googled i saw that this kind of stuff i tried is just not an option. Im looking for a way to be able ro reach scores so theat i can manipulate it but all i find is selekting an aray by thr value of the second item — nikstreat, Feb 27 '22 at 17:34
It's called the spread operator (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax), feel free to add questions to the answer below — Majed Badawi, Feb 27 '22 at 17:49

Majed Badawi · Accepted Answer · 2022-02-27T17:55:01.490

Using Array#sort, sort the array by the sum of scores, or name as fallback (using String#localeCompare)

const arr = [ { name: 'Joe', scores: [1] }, { name: 'Jane', scores: [1, 2] }, { name: 'John', scores: [1, 2] } ];

const sum = (arr = []) => arr.reduce((total, num) => total + num, 0);

const sorted = arr.sort((a, b) => 
  sum(b.scores) - sum(a.scores) || a.name.localeCompare(b.name)
);

console.log(sorted);

score 0 · Answer 2 · answered Feb 27 '22 at 17:51

You could take a Map for all sums and the object as key without mutating data.

const
    data = [{ name: 'Joe', scores: [1, 2, 3] }, { name: 'Jane', scores: [1, 4, 3] }, { name: 'John', scores: [1, 2, 1] }],
    add = (a, b) => a + b,
    sums = new Map(data.map(o => [o, o.scores.reduce(add, 0)]));

data.sort((a, b) => sums.get(b) - sums.get(a) || a.name.localeCompare(b.name));

console.log(data);

.as-console-wrapper { max-height: 100% !important; top: 0; }

score 0 · Answer 3 · answered Feb 27 '22 at 17:57

The lodash package could be handy

const lodash = require('lodash')

const list = [
  { name: 'Joe', scores: [1, 2, 4] },
  { name: 'Jane', scores: [1, 2, 3] },
  { name: 'John', scores: [1, 2, 4] }
]

const listWithSum = list.map(item => {
  return {
    ...item,
    sum: lodash.sum(item.scores)
  }
})

const sortedList = lodash.orderBy(listWithSum, ['score', 'name'], ['desc', 'desc'])

console.log(sortedList)

JavaScript: Sort array of objects by computed property or by an existing property if equal

3 Answers3