Recursive reverse string

[hellocan]

Your objective is to complete a recursive function reverse() that receives str as String and returns the same string in reverse order

Rules:
reverse function should be executed only N times. N = length of the input string
helper functions are not allowed
changing the signature of the function is not allowed
Examples:
reverse("hello world") = "dlrow olleh" (N = 11)
reverse("abcd") = "dcba" (N = 4)
reverse("12345") = "54321" (N = 5)

where By
http://www.codewars.com/kata/536a9f94021a76ef0f00052f/train/javascript

[hellocan]

function reverse(str) {
    var len = str.length;
    arr = str.split('');
    for (var i = 0; i < len / 2; i++) {
        t = arr[len - i - 1];
        arr[len - i - 1] = arr[i];
        arr[i] = t;

    }
    return arr.join("")
}

[Chrono79]

That code doesn't use recursion.