Lesson 11 — sort()

Putting arrays in order

sort() changes an array into sorted order. The catch: by default it compares items as text, so [10, 9, 1].sort() gives [1, 10, 9] ("1" < "9" as text). For numbers, pass a compare function: (a, b) => a - b. A negative result puts a first, positive puts b first.

[5, 1, 4].sort((a, b) => a - b);   // [1, 4, 5]
[5, 1, 4].sort((a, b) => b - a);   // [5, 4, 1]

Why it matters: price lists, leaderboards and dates all need correct numeric sorting.