JavaScript callback function inside sort() a and b variables

Question

I am trying to understand how the sort() function works along with the callback function passed into it. More specifically the values of a and b

Example code:

var n = [4, 11, 2, 10, 3, 1];
    n.sort(function(a, b) {
        console.log(a);
        console.log(b);
        console.log('--')
        return a-b;
    });

Result:

4
11
--
11
2
--
4
2
--
11
10
--
4
10
--
11
3
--
10
3
--
4
3
--
2
3
--
11
1
--
10
1
--
4
1
--
3
1
--
2
1
--

The first round I can follow that a = 4, and b = 11, easy to follow.

The second round I can follow that a = 11 and b = 2.

But after that I sort of loose track of what actually is going, for example when you get to when a = 4 and b = 3. How is this actually working? I tried working it out on paper but could not see the logic in the output of a and b.

Answer 1

Looks like a modified bubble sort. You can see what is happening when you compare the state of the array at each step - I have added them below.

Move the value from index 1 as low as it should go. (index 0-1 are in order) Now move the value from index 2 as low as it should go. (index 0-2 are in order) Now move the value from index 3 as low as it should go. (index 0-3 are in order)

Since we know how much of the array is in order we short circuit the comparisons and jump to the next index as soon as the comparison function is not negative.

4
11
-- [4, 11, 2, 10, 3, 1];
11
2
-- [4, 2, 11, 10, 3, 1];
4
2
-- [2, 4, 11, 10, 3, 1];
11
10
-- [2, 4, 10, 11, 3, 1];
4
10
-- [2, 4, 10, 11, 3, 1];
11
3
-- [2, 4, 10, 3, 11, 1];
10
3
-- [2, 4, 3, 10, 11, 1];
4
3
-- [2, 3, 4, 10, 11, 1];
2
3
-- [2, 3, 4, 10, 11, 1];
11
1
-- [2, 3, 4, 10, 1, 11];
10
1
-- [2, 3, 4, 1, 10, 11];
4
1
-- [2, 3, 1, 4, 10, 11];
3
1
-- [2, 1, 3, 4, 10, 11];
2
1
-- [1, 2, 3, 4, 10, 11];