This one reads odd to me. First, an array is not recursive by itself.
slice does not alter the original array, but returns a new “one level deep” copy that contains copies of the elements sliced from the original array. Elements of the original array are copied into the new array as follows:
For object references (and not the actual object), slice copies object references into the new array. Both the original and new array refer to the same object. If a referenced object changes, the changes are visible to both the new and original arrays.
For strings and numbers (not String and Number objects), slice copies strings and numbers into the new array. Changes to the string or number in one array does not affect the other array.
If a new element is added to either array, the other array is not affected.