Array.sort method not working when sorting by property

Question

I have a basic array, that I'm trying to sort by the source property:

const arr = [
    { source: '64', target: '63' },
    { source: '61', target: '64' },
    { source: '114', target: '63' },
];

console.log('before', arr);

arr.sort(
    (a, b) => a.source > b.source
        // move element to a lower index
        ? -1
            // move element to a higher index
            : b.source > a.source
            ? 1
        : 0);
        
console.log('after', arr);

But this leaves the array untouched. What am I doing wrong here?

In the sort function you are comparing the source property as a string instead of as a number try parsing a.source and b.source to Number — Pablo Silió
– Pablo Silió, Commented Jul 4, 2022 at 10:09
try that - arr.sort((a, b) => parseInt(a.source) - parseInt(b.source)) — marmeladze
– marmeladze, Commented Jul 4, 2022 at 10:09
Even without parsing I guess it would work fine...arr.sort((a, b) => a.source-b.source); — kazmi066
– kazmi066, Commented Jul 4, 2022 at 10:12

dippas · Accepted Answer · 2022-07-04 10:43:16Z

1

Simple way of doing this

You can do it directly without condition inside sort

const arr = [{
    source: '64',
    target: '63'
  },
  {
    source: '61',
    target: '64'
  },
  {
    source: '114',
    target: '63'
  },
];

console.log('before', arr);

arr.sort((a, b) => a.source - b.source); // ascending
//arr.sort((a, b) => b.source - a.source); // descending

console.log('after', arr);

Way of doing this by conversion

Or you can convert string to number, without extra conditions inside your sort

const arr = [{
    source: '64',
    target: '63'
  },
  {
    source: '61',
    target: '64'
  },
  {
    source: '114',
    target: '63'
  },
];

console.log('before', arr);

arr.sort((a, b) => Number(a.source) > Number(b.source) ? -1 : 1);

console.log('after', arr);

edited Jul 4, 2022 at 10:43

answered Jul 4, 2022 at 10:10

dippas

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2 Comments

Mike K Over a year ago

arr.sort((a, b) => a.source - b.source); seems to work, b.source - a.source does not

dippas Over a year ago

sorry @Mike I thought you want descending not ascending :), fixed

Milos Pavlovic · Accepted Answer · 2022-07-04 10:09:14Z

1

You need to convert strings to integers, before making comparisons, otherwise non-empty string will coerce to true and you are basically doing true > true inside your sort resolver.

answered Jul 4, 2022 at 10:09

Milos Pavlovic

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Comments

Alan Friedman · Accepted Answer · 2022-07-04 10:10:45Z

1

You need to either use numbers for the source value or coerce them to numbers, as below:

const arr = [
    { source: '64', target: '63' },
    { source: '61', target: '64' },
    { source: '114', target: '63' },
];

console.log('before', arr);

arr.sort(
    (a, b) => Number(a.source) > Number(b.source)
        // move element to a lower index
        ? -1
            // move element to a higher index
            : Number(b.source) > Number(a.source)
            ? 1
        : 0);
        
console.log('after', arr);

answered Jul 4, 2022 at 10:10

Alan Friedman

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Comments

Classified · Accepted Answer · 2022-07-04 10:17:45Z

1

I think you are over complicating it.

arr.sort((a,b) => a.source - b.source);

answered Jul 4, 2022 at 10:17

Classified

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Comments

JMP · Accepted Answer · 2022-07-04 10:18:37Z

1

Convert your strings in the array to numbers.

const arr = [
    { source: 64, target: 63 },
    { source: 61, target: 64 },
    { source: 114, target: 63 },
];

console.log('before', arr);

arr.sort(
    (a, b) => a.source > b.source
        // move element to a lower index
        ? -1
            // move element to a higher index
            : b.source > a.source
            ? 1
        : 0);
        
console.log('after', arr);

answered Jul 4, 2022 at 10:18

JMP

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Comments

Nina Scholz · Accepted Answer · 2022-07-04 10:42:59Z

0

Your sorting works.

You sort the array by string and descending

'64'
'61'
'114'

and because of having this sorting in your data, nothings happens.

For sorting the values ascending as strings swap 1 and -1.

To get a result of numerical order convert either the values to number or use an implicit conversion by using a numerical operator, like -.

(a, b) => a.source - b.source // ascending
(a, b) => b.source - a.source // descending

answered Jul 4, 2022 at 10:42

Nina Scholz

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