Initial data commit

Task/Cumulative-standard-deviation/JavaScript/cumulative-standard-deviation-2.js

@@ -0,0 +1,22 @@
+(function (xs) {
+
+    return xs.reduce(function (a, x, i) {
+        var n = i + 1,
+            sum_ = a.sum + x,
+            squaresSum_ = a.squaresSum + (x * x);
+
+        return {
+            sum: sum_,
+            squaresSum: squaresSum_,
+            stages: a.stages.concat(
+                Math.sqrt((squaresSum_ / n) - Math.pow((sum_ / n), 2))
+            )
+        };
+
+    }, {
+        sum: 0,
+        squaresSum: 0,
+        stages: []
+    }).stages
+
+})([2, 4, 4, 4, 5, 5, 7, 9]);