Another update from ingydotnet^djgoku

Task/Factorial/JavaScript/factorial-1.js

@@ -1,7 +1,12 @@
 function factorial(n) {
-    var x = 1;
-    for (var i = 2; i <= n; i++) {
-        x *= i;
-    }
-    return x;
+  //check our edge case
+  if (n < 0) { throw "Number must be non-negative"; }
+
+  var sum = 1;
+  //we skip zero and one since both are 1 and are identity
+  while (n > 1) {
+    sum *= n;
+    n -= 1;
+  }
+  return sum;
 }