1 files changed, 54 insertions, 0 deletions
diff --git a/challenge-243/bruce-gray/javascript/ch-2.js b/challenge-243/bruce-gray/javascript/ch-2.js
new file mode 100644
index 0000000000..c5664a5c35
--- /dev/null
+++ b/challenge-243/bruce-gray/javascript/ch-2.js
@@ -0,0 +1,54 @@
+// Procedural
+function task2a ( ns ) {
+    let ret = 0;
+    for     ( const x of ns ) {
+        for ( const y of ns ) {
+            ret += Math.floor( x / y );
+        }
+    }
+    return ret;
+}
+
+// Functional, both using extracted code for Cartesian product.
+const cartesian =
+  (...top_level_arrays) => top_level_arrays.reduce(
+      (accum, an_array) => accum.flatMap(
+             (element1) => an_array.map(
+             (element2) => [element1, element2].flat()
+)));
+
+// .map(), then sum via .reduce .
+function task2b  (ns) {
+    return cartesian(ns, ns)
+          .map(([x,y]) => Math.floor(x/y))
+          .reduce(((a,b) => a+b),0);
+}
+
+// Do the summing *and* mapping during the .reduce .
+const task2c = (ns) => cartesian(ns, ns).reduce(((a,[x,y]) => a+Math.floor(x/y)),0);
+
+
+
+let test_number = 0;
+function is ( got, expected, desc ) {
+    test_number++;
+    const ok_msg = (got === expected) ? "ok" : "not ok";
+    const description = (typeof desc !== 'undefined') ? ` - ${desc}` : '';
+    console.log(`${ok_msg} ${test_number}${description}`);
+}
+const subs = [
+    [ 'task2a', task2a ],
+    [ 'task2b', task2b ],
+    [ 'task2c', task2c ],
+];
+const tests = [
+    [ 10, [2, 5, 9]      , 'Example 1 from task'],
+    [ 49, [7,7,7,7,7,7,7], 'Example 2 from task'],
+    [ 10, [2, 5, 9]      , 'Null array'],
+];
+for     ( const [ sub_name, task2_coderef    ] of subs  ) {
+    for ( const [ expected, input, test_name ] of tests ) {
+        const got = task2_coderef(input);
+        is( got, expected, `${sub_name}: ${test_name}`);
+    }
+}