Merge fix-plus-operation-type-check: Improve Fibonacci function with iterative approach and enhanced error handling

src/fib.ts

@@ -1,12 +1,27 @@
 // util function that computes the fibonacci numbers
-module.exports = function fibonacci(n) {
+function fibonacci(n: number): number {
+  if (typeof n !== 'number' || isNaN(n)) {
+    throw new TypeError('Input must be a valid number');
+  }
+
   if (n < 0) {
-    return -1;
-  } else if (n == 0) {
+    throw new RangeError('Input must be a non-negative integer');
+  } else if (n === 0) {
     return 0;
-  } else if (n == 1) {
+  } else if (n === 1) {
     return 1;
   }
 
-  return fibonacci(n - 1) + fibonacci(n - 2);
-};
+  // Removed redundant type annotations
+  let a = 0;
+  let b = 1;
+  let temp: number;
+
+  for (let i = 2; i <= n; i++) {
+    temp = a + b;
+    a = b;
+    b = temp;
+  }
+  return b;
+}
+export default fibonacci;

src/fibRoute.ts

@@ -1,16 +1,24 @@
-// Endpoint for querying the fibonacci numbers
+import { Request, Response } from 'express';
+import fibonacci from './fib';
 
-const fibonacci = require("./fib");
+export default (req: Request, res: Response): void => {
+  const numString = req.params.num as unknown as string;  // Ensure it's treated as a string
+  const num = parseInt(numString, 10);  // Safely parse num as an integer
 
-export default (req, res) => {
-  const { num } = req.params;
-
-  const fibN = fibonacci(parseInt(num));
-  let result = `fibonacci(${num}) is ${fibN}`;
+  // Check if num is a valid number after parsing
+  if (isNaN(num)) {
+    res.status(400).send('Invalid input. Please provide a valid number.');
+    return;
+  }
 
-  if (fibN < 0) {
-    result = `fibonacci(${num}) is undefined`;
+  // Check if the number is negative
+  if (num < 0) {
+    res.send(`fibonacci(${num}) is undefined`);
+    return;
   }
 
+  const fibN = fibonacci(num);  // Compute the Fibonacci number safely
+  const result = `fibonacci(${num}) is ${fibN}`;  // Use const instead of let
+
   res.send(result);
 };