2016 Update

Task/Range-extraction/JavaScript/range-extraction-2.js

@@ -0,0 +1,45 @@
+(function (lstTest) {
+    'use strict';
+
+    function rangeString(xs) {
+        var iRightmost = xs.length - 1,
+
+            // Using foldr/reduceRight proves simpler here than foldl/reduce
+            // (the left end of the list is easier to reach than the tip of the tail)
+            lstSeries = xs.reduceRight(function (a, x, i, l) {
+
+                return i < iRightmost ? (
+
+                    // new series if rightward gap > 1
+                    l[i + 1] - x > 1 ? (
+                        [[x]].concat(a)
+                    ) : (
+
+                        // This value prepended to current series (if a
+                        // series-breaker, or the start of the list, is at left)
+                        (i === 0 || (x - l[i - 1]) > 1) ? (
+                            [[x].concat(a[0])].concat(a.slice(1))
+
+                            // or, if the series continues to the left,
+                            // just an unmodified copy of the accumulator
+                        ) : a
+                    )
+                ) : [[x]];
+
+            }, []);
+
+        return lstSeries.map(function (r) {
+            var lng = r.length,
+                d = lng > 1 ? r[1] - r[0] : 0;
+
+            return d ? r[0] + (d > 1 ? '-' : ',') + r[1] : r[0];
+
+        }).join(',');
+    }
+
+    return rangeString(lstTest);
+
+})([0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
+   15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
+   25, 27, 28, 29, 30, 31, 32, 33, 35, 36,
+   37, 38, 39]);

Task/Range-extraction/JavaScript/range-extraction-3.js

@@ -0,0 +1 @@
+"0-2,4,6-8,11,12,14-25,27-33,35-39"