Another update from ingydotnet^djgoku

Task/Perfect-numbers/JavaScript/perfect-numbers-2.js

@@ -0,0 +1,19 @@
+(function (nFrom, nTo) {
+
+  function perfect(n) {
+    return n === range(1, n - 1).reduce(
+      function (a, x) {
+        return n % x ? a : a + x;
+      }, 0
+    );
+  }
+
+  function range(m, n) {
+    return Array.apply(null, Array(n - m + 1)).map(function (x, i) {
+      return m + i;
+    });
+  }
+
+  return range(nFrom, nTo).filter(perfect);
+
+})(1, 10000);

Task/Perfect-numbers/JavaScript/perfect-numbers-3.js

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

Task/Perfect-numbers/JavaScript/perfect-numbers-4.js

@@ -0,0 +1,23 @@
+(function (nFrom, nTo) {
+
+  function perfect(n) {
+    var lows = range(1, Math.floor(Math.sqrt(n))).filter(function (x) {
+      return (n % x) === 0;
+    });
+
+    return n > 1 && lows.concat(lows.map(function (x) {
+      return n / x;
+    })).reduce(function (a, x) {
+      return a + x;
+    }, 0) / 2 === n;
+  }
+
+  function range(m, n) {
+    return Array.apply(null, Array(n - m + 1)).map(function (x, i) {
+      return m + i;
+    });
+  }
+
+  return range(nFrom, nTo).filter(perfect)
+
+})(1, 10000);

Task/Perfect-numbers/JavaScript/perfect-numbers-5.js

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

Task/Perfect-numbers/JavaScript/perfect-numbers-6.js

@@ -0,0 +1,35 @@
+(function (nFrom, nTo) {
+
+  // MONADIC CHAIN (bind) IN LIEU OF FILTER
+  // ( monadic return for lists is just lambda x -> [x] )
+
+  return chain(
+    rng(nFrom, nTo),
+
+    function mPerfect(n) {
+      return (chain(
+        rng(1, Math.floor(Math.sqrt(n))),
+        function (y) {
+          return (n % y) === 0 && n > 1 ? [y, n / y] : [];
+        }
+      ).reduce(function (a, x) {
+        return a + x;
+      }, 0) / 2 === n) ? [n] : [];
+    }
+
+  );
+
+  /******************************************************************/
+
+  // Monadic bind (chain) for lists
+  function chain(xs, f) {
+    return [].concat.apply([], xs.map(f));
+  }
+
+  function rng(m, n) {
+    return Array.apply(null, Array(n - m + 1)).map(function (x, i) {
+      return m + i;
+    });
+  }
+
+})(1, 10000);

Task/Perfect-numbers/JavaScript/perfect-numbers-7.js

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