Array Sort

Array Sort

sort() arranges the items of an array. Be careful: the default sort treats items as text.

The default sort

["cherry", "apple", "banana"].sort();
// ["apple", "banana", "cherry"]

Strings sort alphabetically by default.

The number trap

The default sort converts numbers to strings, so [10, 9, 80] sorts as ["10", "80", "9"]:

[10, 9, 80].sort(); // [10, 80, 9] (wrong order!)

Sort numbers correctly

Provide a compare function:

[10, 9, 80].sort(function(a, b) {
  return a - b;
});
// [9, 10, 80]

• Negative result: a goes before b.
• Positive result: b goes before a.
• Zero: they stay.

Sort descending

[10, 9, 80].sort((a, b) => b - a); // [80, 10, 9]

reverse

reverse() flips the order of an array:

[1, 2, 3].reverse(); // [3, 2, 1]

TL;DR

• sort() works well for strings by default.
• Numbers need a compare function (a, b) => a - b.
• reverse() flips the array order.