Javascript Array Sort function not sorting properly

Question

I have a question regarding javascript's sort() function

var arr = [23,43,54,2,3,12];
arr.sort();

it's output is [12, 2, 23, 3, 43, 54] well it should be [2, 3, 12, 23, 43, 54]?

https://stackoverflow.com/questions/1063007/how-to-sort-an-array-of-integers-correctly — aahhaa, Sep 11 '17 at 18:02
Possible duplicate of [How to sort an array of integers correctly](https://stackoverflow.com/questions/1063007/how-to-sort-an-array-of-integers-correctly) — Brian, Sep 11 '17 at 18:02
it's taking the first digit when sorting as your values represent strings — pokeybit, Sep 11 '17 at 18:02

spanky · Accepted Answer · 2017-09-11T18:14:18.850

3

It's because you're sorting the numbers with the default sorting algorithm, which converts them to a string and sorts lexicographically.

Instead pass a function defining a sort order via its return value.

var arr = [23,43,54,2,3,12]; 

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

Returning a positive number moves a toward the end of the list.

edited Sep 11 '17 at 18:14

answered Sep 11 '17 at 18:02

spanky

Titian Cernicova-Dragomir · Answer 2 · 2017-09-11T18:15:42.210

2

You have to specify a sort function

[12, 2, 23, 3, 43, 54].sort(function (a, b) { return  a - b ; } )

The javascript specification states that sort should perform lexicografic sorting, docs

edited Sep 11 '17 at 18:15

answered Sep 11 '17 at 18:02

You shouldn't return a boolean. The sorter expects a numeric return value. Returning a boolean may give incorrect results in some cases. – spanky Sep 11 '17 at 18:11
@spanky you are right, changed to address this feedback, – Titian Cernicova-Dragomir Sep 11 '17 at 18:16

score 1 · Answer 3 · answered Sep 11 '17 at 18:06

1

The sorting of number is based on Unicode. Hence the oder you have is correct. Refer the link for details.

answered Sep 11 '17 at 18:06

Kniwx

3 Answers3