How can I remove all but the last N elements from an array? [closed]

Question

I have an array. I have a variable that shows how many elements in the array must be left at the end. Is there a function that would do that? Example:

var arr = [1, 2, 3, 4, 5];
var n = 2;
arr = someFunction(n); // arr = [4, 5];

I want an array with the last n elements in it.

Answer 1

The slice method is what you want. It returns a new object, so you must replace your existing object with the new one.

arr = arr.slice(-1 * n);

Alternatively, modify the existing array with splice().

arr.splice(0, arr.length - n);

Splice is the more efficient, since it is not copying elements.