Add calculateRectangleArea function with unit tests

.gitignore

@@ -0,0 +1 @@
+node_modules/ 

src/index.js

@@ -8,10 +8,16 @@
 // Import the factorial function from the factorial.js file
 const { factorial } = require('./utils/factorial');
 
+// Import the rectangle area function from the rectangle.js file
+const { calculateRectangleArea } = require('./utils/rectangle');
+
 // The main() function calculates the factorial of 5 and logs the result to the console
 async function main () {
   const result = factorial(5); // Call the factorial function with the value of 5
   console.log('factorial of 5 is', result); // Log the result to the console
+
+  const area = calculateRectangleArea(5, 10); // Call the calculateRectangleArea function
+  console.log('area of rectangle (5 x 10) is', area); // Log the result to the console
 }
 
-main(); // Call the main function to calculate the factorial of 5
+main(); // Call the main function to calculate the factorial of 5, and also calculate the area of a 5 x 10 rectangle.

src/utils/rectangle.js

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+/**
+ * Author: Ben Hilarides
+ * Date: 16 January 2026
+ * File: rectangle.spec.js
+ * Description: This script tests the rectangle area calculation function.
+ */
+'use strict';
+
+/**
+ * Calculates the area of a rectangle.
+ * @param {number} length - The length of the rectangle
+ * @param {number} width - The width of the rectangle
+ * @returns {number} The area of the rectangle
+ */
+function calculateRectangleArea(length, width) {
+    return length * width;
+}
+
+module.exports = {
+    calculateRectangleArea
+}

test/utils/rectangle.spec.js

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+/**
+ * Author: Ben Hilarides
+ * Date: 16 January 2026
+ * File: rectangle.spec.js
+ * Description: This script tests the rectangle area calculation function.
+ */
+'use strict';
+
+const { calculateRectangleArea } = require('../../src/utils/rectangle'); // Import the rectangle area function from the rectangle.js file
+
+// The describe() function is a test suite that contains one or more tests
+describe('rectangle.js', () => {
+
+    // Test for calculating area with positive integers
+    it('should calculate area of 5 x 10 as 50', () => {
+        const result = calculateRectangleArea(5, 10);
+        expect(result).toBe(50);
+    });
+
+    // Test for calculating area of a square
+    it('should calculate area of 5 x 5 as 25', () => {
+        const result = calculateRectangleArea(5, 5);
+        expect(result).toBe(25);
+    });
+
+    // Test for calculating area with decimal values
+    it('should calculate are of 3.5 x 2.5 as 8.75', () => {
+        const result = calculateRectangleArea(3.5, 2.5);
+        expect(result).toBe(8.75);
+    });
+})