Sort array of strings with negative and positive numbers

Question

Firstly I could not find a question addressing the whole issue.

I used to compare arrays like this:

array.sort((a, b) => {
    return a.localeCompare(b, undefined, {numeric: true, sensitivity: 'base'})
})

But I realized it does not work on an array like ['a', 'A', 'B', -1.50', '0', '1.50', '-2', '2'].

The expected output would be: ['-2', '-1.50', '0', '1.50', '2', 'A', 'a', 'B'].

I have some dirty ideas to achieve it. But maybe there is a clean and easy way.

Given an array of objects, I parameterized the attribute of the object, so that I won't write a sort method for different attributes. — Ali Ankarali, May 09 '18 at 07:42
I guess it is not much relevant to the question so removed it to avoid confusion. — Ali Ankarali, May 09 '18 at 07:44

score 7 · Accepted Answer · edited May 09 '18 at 08:07

7

You could prepend the comparison by taking the delta of the wanted properties. This saves the order for numerical values.

console.log(
    ['a', 'A', 'B', '-1.50', '0', '1.50', '-2', '2', 'D']
        .sort((a, b) => a - b || a.localeCompare(b, undefined, {sensitivity: 'base'}))
);

numeric: true option can be omitted for there won't be two numbers to compare at the left hand side of the expression.

edited May 09 '18 at 08:07

Ali Ankarali

2,761
3
18
30

answered May 09 '18 at 07:44

Nina Scholz

376,160
25
347
392

I guess in this case we already look whether it is number or not, so it would be better if we omit `numeric: true` option for performance. – Ali Ankarali May 09 '18 at 07:57

Mihai Alexandru-Ionut · Answer 2 · 2018-05-09T08:18:29.693

You should use isNaN method in order to check if you compare numerical strings. If yes, localeCompare is not recommended , you need to use Number(a) - Number(b)

array = ['a', 'A', 'B','-1.50', '0', '1.50', '-2', '2']
array.sort((a, b) => {
  return !isNaN(a) && !isNaN(b) ? Number(a)-Number(b) : a.localeCompare(b, undefined, { sensitivity: 'base'});
})
    
console.log(array);

Since in Javascript the - operator is defined only for numeric subtraction, the operands will be coerced to Number. So you could simply use:

array.sort((a, b) => {
  return a - b || a.localeCompare(b, undefined, { sensitivity: 'base'});
})

score 2 · Answer 3 · answered May 09 '18 at 07:46

const customSort = (array) => {
    return array.sort((a, b) => {

        let r = /^-?\d+(?:\.\d+)?$/;

        if (r.test(a) && r.test(b))
        {
            return a - b;
        }

        return a.localeCompare(b, undefined, {numeric: true, sensitivity: 'base'})
    })
}

console.log(customSort(['a', 'A', 'B', '-1.50', '0', '1.50', '-2', '2']));
// => [ '-2', '-1.50', '0', '1.50', '2', 'a', 'A', 'B' ]

Sort array of strings with negative and positive numbers

3 Answers3