numeric array sort()

Question

Is this part from the book "Learning PHP, MySql and Javascript by. Robin Nixon" wrong?

numbers = [7, 23, 6, 74];

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

output is 6,7,23,74

The book says:

If the anonymous function inside sort() returns a value greater than zero, the sort assumes a comes before b.

If the anonymous function inside sort() return a value less than zero, the sort assumes b comes before a.

The sort runs this function across all the values in the array to determine their order.

is this wrong? Because....

a here is 7
b here is 23

7 - 23 = -16 // a number less than zero. Book says it should b comes before a.

so the final output should be 74, 23, 7, 6

You know, you could just: _try it out_. Like in the above jsfiddle — TheZ, Jul 06 '12 at 18:28
Currently the numbers are being sorted from smallest to largest. What you think the final output should be is largest to smallest. It's an easy tweak to make it decrement. — Chad, Jul 06 '12 at 18:29
im just asking if the explanation from the book is wrong i know the output is 6,7,23,74 — Zzaaznedog Dafdf, Jul 06 '12 at 18:29
Thats what im asking so the explanation from the book is wrong. Thanks guys. — Zzaaznedog Dafdf, Jul 06 '12 at 18:30
What are we discussing here? Is book right or wrong? The fact is your script,not a book. — Engineer, Jul 06 '12 at 18:30
@AlienWebguy Nobody argues,that reading books is good thing, but here, the fact is script shows other results,than book says.So you must believe in script,and not in book. — Engineer, Jul 06 '12 at 18:43

score 5 · Answer 1 · answered Jul 06 '12 at 18:29

5

It appears that it is wrong. From MDN:

If compareFunction(a, b) is less than 0, sort a to a lower index than b.

("Lower index" in this case would mean that a comes before b)

answered Jul 06 '12 at 18:29

andypaxo

6,171
3
38
53

score 2 · Answer 2 · answered Jul 06 '12 at 18:30

2

The output is correct, but the explanation is not. If the method returns < 0, a comes before b.

answered Jul 06 '12 at 18:30

David Kanarek

12,611
5
45
62

numeric array sort()

2 Answers2