The output is `[1, 2, 3, 4, 5]`. This code demonstrates using an arrow function as a comparator for the `sort()` method. The `sort()` method sorts the elements of an array in place and returns the sorted array. When a comparator function is provided, it determines the sorting order based on its return value: negative if `a` should come before `b`, positive if `a` should come after `b`, or zero if they're equivalent. The arrow function `(a, b) => a - b` provides a concise way to express numeric ascending sort. By subtracting `b` from `a`, it returns a negative value when `a` is less than `b`, ensuring smaller numbers come first. This is a common pattern for numeric sorting in JavaScript, and arrow functions make it more readable than the equivalent function expression. Note that `sort()` modifies the original array in place, so the `numbers` array itself is changed to the sorted order. To sort in descending order, the comparator would be `(a, b) => b - a`.