2016 Update

Task/Five-weekends/JavaScript/five-weekends-3.js

@@ -0,0 +1,57 @@
+(function () {
+    'use strict';
+
+
+    // longMonthsStartingFriday :: Int -> Int
+    function longMonthsStartingFriday(y) {
+        return [0, 2, 4, 6, 7, 9, 11]
+            .filter(function (m) {
+                return (new Date(Date.UTC(y, m, 1)))
+                    .getDay() === 5;
+            });
+    }
+
+
+    // range :: Int -> Int -> [Int]
+    function range(m, n) {
+        return Array.apply(null, Array(n - m + 1))
+            .map(function (x, i) {
+                return m + i;
+            });
+    }
+
+    var lstNames = [
+            'January', '', 'March', '', 'May', '',
+            'July', 'August', '', 'October', '', 'December'
+        ],
+
+        lstYears = range(1900, 2100),
+
+        lstFullMonths = lstYears
+        .reduce(function (a, y) {
+            var strYear = y.toString();
+
+            return a.concat(
+                longMonthsStartingFriday(y)
+                .map(function (m) {
+                    return strYear + ' ' + lstNames[m];
+                })
+            );
+        }, []),
+
+        lstLeanYears = lstYears
+        .filter(function (y) {
+            return longMonthsStartingFriday(y)
+                .length === 0;
+        });
+
+    return JSON.stringify({
+            number: lstFullMonths.length,
+            firstFive: lstFullMonths.slice(0, 5),
+            lastFive: lstFullMonths.slice(-5),
+            leanYearCount: lstLeanYears.length
+        },
+        null, 2
+    );
+
+})();