Sorting an array of decimal & whole numbers

Question

I can't seem to figure this one out.

var arr = [2.62, 111.05, 1.05]
arr.sort();

This returns [1.05, 111.05, 2.62], but I'm expecting [1.05, 2.62, 111.05].

How can this be achieved? I've read a bit about writing a custom sort to split the "decimal" but haven't managed to have any success.

not familiar with javascript but the sorting seems as if the elements are strings rather than float — advocateofnone, Feb 10 '15 at 21:41

styvane · Accepted Answer · 2015-02-10T21:52:19.000

16

By default sorting is alphabetically. You need to pass a function to the sort method

arr.sort(function(a, b){return a-b;});

edited Feb 10 '15 at 21:52

answered Feb 10 '15 at 21:42

styvane

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If it still does not work, try this: arr.sort(function(a,b){return a > b;}); – s.n Feb 07 '19 at 20:37
@s.n that's incorrect, `>` will compare `a` and `b` as strings and hence still alphabetically – Anti Earth Aug 04 '21 at 07:12

Guffa · Answer 2 · 2015-02-10T21:48:21.530

9

The sort method compares the items as strings by default. You can specify a comparer function to make the comparison any way you like. This will compare the items as numbers:

arr.sort(function(a, b){ return a - b; });

Note: All numbers in Javascript a double precision floating point numbers, even if they happen to contain an integer value, so integer values and decimal values are not treated differently.

edited Feb 10 '15 at 21:48

answered Feb 10 '15 at 21:42

Guffa

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score 2 · Answer 3 · answered Feb 10 '15 at 21:42

This is the normal behavior for Array.sort() when it isn't given a comparator function. Try this:

var arr = [2.62, 111.05, 1.05];
arr.sort(function(a,b) { return a-b; });

From MDN:

If compareFunction is not supplied, elements are sorted by converting them to strings and comparing strings in Unicode code point order. For example, "Cherry" comes before "banana". In a numeric sort, 9 comes before 80, but because numbers are converted to strings, "80" comes before "9" in Unicode order.

Sorting an array of decimal & whole numbers

3 Answers3