Another update from ingydotnet^djgoku

Task/Loop-over-multiple-arrays-simultaneously/JavaScript/loop-over-multiple-arrays-simultaneously-2.js

@@ -0,0 +1,14 @@
+var lstOut = ['', '', ''];
+
+[["a", "b", "c"], ["A", "B", "C"], ["1", "2", "3"]].forEach(
+  function (a) {
+    [0, 1, 2].forEach(
+      function (i) {
+        // side-effect on an array outside the function
+        lstOut[i] += a[i];
+      }
+    );
+  }
+);
+
+// lstOut --> ["aA1", "bB2", "cC3"]

Task/Loop-over-multiple-arrays-simultaneously/JavaScript/loop-over-multiple-arrays-simultaneously-3.js

@@ -0,0 +1,17 @@
+(function (lstArrays) {
+
+    return lstArrays.reduce(
+        function (a, e) {
+            return [
+                a[0] + e[0],
+                a[1] + e[1],
+                a[2] + e[2]
+            ];
+        }, ['', '', ''] // initial copy of the accumulator
+    ).join('\n');
+
+})([
+    ["a", "b", "c"],
+    ["A", "B", "C"],
+    ["1", "2", "3"]
+]);

Task/Loop-over-multiple-arrays-simultaneously/JavaScript/loop-over-multiple-arrays-simultaneously-4.js

@@ -0,0 +1,16 @@
+(function (x, y, z) {
+
+    // function of arity 3 mapped over nth items of each of 3 lists
+    // (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
+    function zipWith3(f, xs, ys, zs) {
+        return zs.length ? [f(xs[0], ys[0], zs[0])].concat(
+            zipWith3(f, xs.slice(1), ys.slice(1), zs.slice(1))) : [];
+    }
+
+    function concat(x, y, z) {
+        return ''.concat(x, y, z);
+    }
+
+    return zipWith3(concat, x, y, z).join('\n')
+
+})(["a", "b", "c"], ["A", "B", "C"], [1, 2, 3]);

Task/Loop-over-multiple-arrays-simultaneously/JavaScript/loop-over-multiple-arrays-simultaneously-5.js

@@ -0,0 +1,24 @@
+(function (lists) {
+
+    // [[a]] -> [[a]]
+    function zip(lists) {
+        var lng = lists.length,
+            lstHead = lng ? [].concat.apply([], lists.map(function (lst) {
+                return lst.length ? [lst[0]] : [];
+            })) : [];
+
+        return lstHead.length === lng ? [lstHead].concat(
+            zip(lists.map(function (x) {
+                return x.slice(1);
+            }))
+        ) : [];
+    }
+
+    // [a] -> s
+    function concat(lst) {
+        return ''.concat.apply('', lst);
+    }
+
+    return zip(lists).map(concat).join('\n')
+
+})([["a", "b", "c"], ["A", "B", "C"], [1, 2, 3]]);

Task/Loop-over-multiple-arrays-simultaneously/JavaScript/loop-over-multiple-arrays-simultaneously-6.js

@@ -0,0 +1,3 @@
+aA1
+bB2
+cC3