2016 Update

Task/Perfect-numbers/JavaScript/perfect-numbers-8.js

@@ -0,0 +1,24 @@
+((nFrom, nTo) => {
+
+    // perfect :: Int -> Bool
+    let perfect = n => {
+            let lows = range(1, Math.floor(Math.sqrt(n)))
+                .filter(x => (n % x) === 0);
+
+            return n > 1 && lows.concat(lows.map(x => n / x))
+                .reduce((a, x) => (a + x), 0) / 2 === n;
+        },
+
+        // range :: Int -> Int -> Maybe Int -> [Int]
+        range = (m, n, step) => {
+            let d = (step || 1) * (n >= m ? 1 : -1);
+
+            return Array.from({
+                length: Math.floor((n - m) / d) + 1
+            }, (_, i) => m + (i * d));
+        };
+
+    return range(nFrom, nTo)
+        .filter(perfect);
+
+})(1, 10000);

Task/Perfect-numbers/JavaScript/perfect-numbers-9.js

@@ -0,0 +1 @@
+[6, 28, 496, 8128]