reduce() method is a bit more flexible. It can return anything. Its purpose is to take an array and condense its content into a single value. That value can be a number, a string, or even an object or new array.

Does reduce return a new object?

5 Answers. Yes, this is the normal behaviour of reduce when you don't pass an initial value for the accumulator (which you always should). Your code doesn't work as expected on any arrays other than those with two objects.

Does array map return a new array?

The map() method returns an entirely new array with transformed elements and the same amount of data. In the case of forEach() , even if it returns undefined , it will mutate the original array with the callback .