Numeric Sort.

Seventh class. sort() without a comparator orders as strings: [10, 2, 1] → "1","10","2" — wrong for amounts.

For numbers pass a comparator: (a, b) => a - b (ascending) or b - a (descending). sort mutates the array in place.

Mini example:

const amounts = [40, 12, 25]; amounts.sort((a, b) => a - b); console.log(amounts);

Common mistake: amounts.sort() with no comparator for numbers; or expecting a new array without mutation (sort returns the same array).