Sorting an array of objects in Chrome

Question

EDIT: As noted by kennytm below and after investigating myself, according to the ECMA spec, when two objects are determined to be equal in a custom sort, JavaScript is

Answer 1

The ECMAScript standard does not guarantee Array.sort is a stable sort. Chrome (the V8 engine) uses in-place QuickSort internally (for arrays of size ≥ 22, else insertion sort) which is fast but not stable.

To fix it, make customSort compare with .b as well, eliminating the need of stability of the sorting algorithm.

Answer 2

The V8 sort is not stable, unfortunately. I'll see if I can dig up the Chromium bug about this.

V8 sort is now stable!

Answer 3

May be you know it already but you can use an array to sort on multiple columns and avoid this bug:

var customSort = function(a,b) {
    return [a.a, a.b] > [b.a, b.b] ? 1:-1;
}