add tasks starting with a number

Task/100-doors/JavaScript/100-doors-2.js

@@ -0,0 +1,19 @@
+var
+ n = 100,
+ doors = [n],
+ step,
+ idx;
+// now, start opening and closing
+for (step = 1; step <= n; step += 1)
+ for (idx = step; idx <= n; idx += step)
+ // toggle state of door
+ doors[idx] = !doors[idx];
+
+// find out which doors are open
+var open = doors.reduce(function(open, val, idx) {
+    if (val) {
+        open.push(idx);
+    }
+    return open;
+}, []);
+document.write("These doors are open: " + open.join(', '));