Fantom code:

echo((0..<20).toList.sort)

or more sharp example

list := Int[,]
20.times { list.add(it) }
echo(list.sort)

jvm output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

js output:

[0, 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 3, 4, 5, 6, 7, 8, 9]

Promoted to ticket #1390 and assigned to andy

Ticket resolved in 1.0.59

Yep, List was not delegating to Obj.compare for default sorts (not sure how that hasn't come up before). But pushed a fix for both sort and sortr.