2016 Update

Task/Flatten-a-list/JavaScript/flatten-a-list-2.js

@@ -1,3 +1,18 @@
-let flatten = list => list.reduce(
-    (a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []
-);
+(function () {
+    'use strict';
+
+    // flatten :: Tree a -> [a]
+    function flatten(t) {
+        return (t instanceof Array ? concatMap(flatten, t) : t);
+    }
+
+    // concatMap :: (a -> [b]) -> [a] -> [b]
+    function concatMap(f, xs) {
+        return [].concat.apply([], xs.map(f));
+    }
+
+    return flatten(
+        [[1], 2, [[3, 4], 5], [[[]]], [[[6]]], 7, 8, []]
+    );
+
+})();

Task/Flatten-a-list/JavaScript/flatten-a-list-3.js

@@ -0,0 +1,4 @@
+    // flatten :: Tree a -> [a]
+    function flatten(a) {
+        return a instanceof Array ? [].concat.apply([], a.map(flatten)) : a;
+    }

Task/Flatten-a-list/JavaScript/flatten-a-list-4.js

@@ -0,0 +1,13 @@
+(function () {
+    'use strict';
+
+    // flatten :: Tree a -> [a]
+    function flatten(a) {
+        return a instanceof Array ? [].concat.apply([], a.map(flatten)) : a;
+    }
+
+    return flatten(
+        [[1], 2, [[3, 4], 5], [[[]]], [[[6]]], 7, 8, []]
+    );
+
+})();

Task/Flatten-a-list/JavaScript/flatten-a-list-5.js

@@ -0,0 +1,3 @@
+let flatten = list => list.reduce(
+    (a, b) => a.concat(Array.isArray(b) ? flatten(b) : b), []
+);

Task/Flatten-a-list/JavaScript/flatten-a-list-6.js

@@ -0,0 +1,12 @@
+function flatten(list) {
+  for (let i = 0; i < list.length; i++) {
+    while (true) {
+      if (Array.isArray(list[i])) {
+      	list.splice(i, 1, ...list[i]);
+      } else {
+      	break;
+      }
+    }
+  }
+  return list;
+}