Array.sort method not working when sorting by property-CodePudding

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?

CodePudding user response：

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);

CodePudding user response：

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.

CodePudding user response：

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);

CodePudding user response：

I think you are over complicating it.

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

CodePudding user response：

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);

CodePudding user response：

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