Rotate the elements in an array in JavaScript

Question

I was wondering what was the most efficient way to rotate a JavaScript array.

I came up with this solution, where a positive n rotates the array to the

Answer 1

Non mutating solution

var arr = ['a','b','c','d']
arr.slice(1,arr.length).concat(arr.slice(0,1)

with mutation

var arr = ['a','b','c','d']
arr = arr.concat(arr.splice(0,1))