2016 Update

Task/Factorial/JavaScript/factorial-4.js

@@ -1 +1,27 @@
-var factorial = n => (n < 2) ? 1 : n * factorial(n - 1);
+(function () {
+    'use strict';
+
+    // factorial :: Int -> Int
+    function factorial(x) {
+
+        return range(1, x)
+            .reduce(function (a, b) {
+                return a * b;
+            }, 1);
+    }
+
+
+
+    // range :: Int -> Int -> [Int]
+    function range(m, n) {
+        var a = Array(n - m + 1),
+            i = n + 1;
+
+        while (i-- > m) a[i - m] = i;
+        return a;
+    }
+
+
+    return factorial(18);
+
+})();