ronaldroe · December 13, 2023 15:27 · Dec 13, 2023 · Mar 10, 2020 · Mar 9, 2020 · Mar 9, 2020
diff --git a/flatten-test.js b/flatten-test.js
@@ -1,4 +1,3 @@
-// Decided against a testing framework for something so simple.
 // This test takes an array, loops through each top level index
 // and logs an error if the index contains an array.
 // Passes are tallied, and passes/fails are output at the end of the test.

diff --git a/flatten.js b/flatten.js
@@ -12,7 +12,7 @@ const flatten = arr => {
 
         // If the current item is an array, recurse into it.
         // It's usually better to not use recursion, but in this case,
-        // it makes it easier to continue to the next level.
+        // depth is unknown, and recursion makes sense.
         } else {
 
             // Spread the results of the recursion into the output array.

diff --git a/flatten-test.js b/flatten-test.js
@@ -0,0 +1,35 @@
+// Decided against a testing framework for something so simple.
+// This test takes an array, loops through each top level index
+// and logs an error if the index contains an array.
+// Passes are tallied, and passes/fails are output at the end of the test.
+
+const flattenTest = arr => {
+
+    // Define error message and initialize pass counter
+    const errorMessage = ind => `Index ${ind} contains an array`;
+    let passCount = 0;
+
+    arr.forEach((item, ind) => {
+
+        // If the item is an array, log the message
+        if(Array.isArray(item)){
+
+            console.error(errorMessage(ind));
+
+        // If not an array, increment pass counter
+        } else {
+
+            passCount++;
+
+        }
+
+    });
+
+    // Log out results
+    console.log(`${arr.length} total top level indexes.`);
+    console.log(`${passCount} tests passed.`);
+    console.log(`${arr.length - passCount} tests failed.`);
+
+}
+
+module.exports = flattenTest;
diff --git a/flatten.js b/flatten.js
@@ -0,0 +1,30 @@
+const flatten = arr => {
+
+    let outputArr = [];
+
+    // Loop through each index of the array
+    arr.forEach(item => {
+
+        // If the current item is not an array, push its value immediately.
+        if(!Array.isArray(item)){
+
+            outputArr.push(item);
+
+        // If the current item is an array, recurse into it.
+        // It's usually better to not use recursion, but in this case,
+        // it makes it easier to continue to the next level.
+        } else {
+
+            // Spread the results of the recursion into the output array.
+            outputArr.push(...flatten(item));
+
+        }
+
+    });
+
+    return outputArr;
+
+}
+
+// Created for use with Node or other CommonJS
+module.exports = flatten;
diff --git a/index.js b/index.js
@@ -0,0 +1,15 @@
+// Run this file using `node index.js` to see results.
+const flattenTest = require('./flatten-test.js');
+const flatten = require('./flatten.js');
+
+const arr = [[1,2,[3]],4];
+
+// First, test flatten function
+console.log('Running example array with flatten function');
+
+flattenTest(flatten(arr));
+
+// Second, show test failures using input array
+console.log('\nRunning example array without flatten function')
+
+flattenTest(arr);
No results found