How to reset and update object value in JavaScript

Question

¡Hello! I have this object, and i’m trying to sort it by the amount of money they produce in a year ( Gross domestic product ) [GDP] and at the same time updates the property called rank from highest to lowest GDP.

const countryData = [
  { rank: 5, name: "Norway", gpd: 77975.4 },
  { rank: 3, name: "Macao", gpd: 81151.9 },
  { rank: 4, name: "Ireland", gpd: 77771.2 },
  { rank: 2, name: "Luxembourg", gpd: 113196.5 },
  { rank: 6, name: "Qatar", gpd: 69687.7 },
  { rank: 1, name: "Switzerland", gpd: 83716.8 },
];

Output should look like this:

const countryData = [
  { rank: 1, name: "Luxembourg", gpd: 113196.5 },
  { rank: 2, name: "Switzerland", gpd: 83716.8 },
  { rank: 3, name: "Macao", gpd: 81151.9 },
  { rank: 4, name: "Norway", gpd: 77975.4 },
  { rank: 5, name: "Ireland", gpd: 77771.2 },
  { rank: 6, name: "Qatar", gpd: 69687.7 },
];

I been trying with sort() method, like this:

const orderer = countryData.sort((a,b) => 
  a.gpd < b.gpd ? 1 : -1);
  console.log(orderer);

And works! but i have no clue of how reset and update rank, i know should be with map() method or for loop.

Thanks in advance!

deep clone surely isn't necessary with this data. A shallow copy will do the job since there are no nested objects/arrays. — Robin Zigmond
– Robin Zigmond, Commented Oct 9, 2020 at 21:13
You have to deep clone since the user wants to alter the rank. — Taplar
– Taplar, Commented Oct 9, 2020 at 21:13
Actually there may be some confusion there. "but i have no clue of how reset and update rank" <= what exactly does that mean? I understand what update rank means. But what do you mean by "reset"? — Taplar
– Taplar, Commented Oct 9, 2020 at 21:17

Barmar · Accepted Answer · 2020-10-09 21:21:40Z

2

After you sort the data, loop through the array and reassign the ranks.

const countryData = [
  { rank: 5, name: "Norway", gpd: 77975.4 },
  { rank: 3, name: "Macao", gpd: 81151.9 },
  { rank: 4, name: "Ireland", gpd: 77771.2 },
  { rank: 2, name: "Luxembourg", gpd: 113196.5 },
  { rank: 6, name: "Qatar", gpd: 69687.7 },
  { rank: 1, name: "Switzerland", gpd: 83716.8 },
];

const orderer = countryData.sort((a,b) => 
  a.gpd < b.gpd ? 1 : -1);

orderer.forEach((o, i) => o.rank = i+1);
console.log(orderer);

answered Oct 9, 2020 at 21:21

Barmar

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Comments

score 0 · Accepted Answer · 2020-10-10 10:57:43Z

0

Maybe like this?

const countryData = [
  { rank: 5, name: "Norway", gpd: 77975.4 },
  { rank: 3, name: "Macao", gpd: 81151.9 },
  { rank: 4, name: "Ireland", gpd: 77771.2 },
  { rank: 2, name: "Luxembourg", gpd: 113196.5 },
  { rank: 6, name: "Qatar", gpd: 69687.7 },
  { rank: 1, name: "Switzerland", gpd: 83716.8 }
]

// Name every function to make it testable
// (maybe later, but...):
const by = prop => (a, b) => a[prop] < b[prop] ? 1 : -1
const update = rank => (o, i) => Object.assign({}, o, o[rank] = ++i)

// Now you can do that task in universal,
// testable and readable way:
const ordered = countryData
  .sort(by('gpd'))
  .map(update('rank'))

console.log(ordered)

edited Oct 10, 2020 at 10:57

answered Oct 9, 2020 at 22:04

user9805590

Comments

RicardoRien · Accepted Answer · 2020-10-21 20:24:23Z

0

This was y solution. It looks cleaner:

let countryDataUpdate = countryData;
countryDataUpdate.sort((a,b) => a.gpd < b.gpd ? 1 : -1)
.map((value, index) => {
  value.rank = index + 1;
  return value;
});

answered Oct 21, 2020 at 20:24

RicardoRien

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