Fix issues

Author: mhmansoo

src/fib.ts

@@ -1,13 +1,13 @@
 // src/fib.ts
-export default function fibonacci(n: number): number {
+export function fibonacci(n: number): number {
   if (n < 0) return -1;
   if (n === 0) return 0;
   if (n === 1) return 1;
 
   let a = 0;
   let b = 1;
   for (let i = 2; i <= n; i++) {
-    const next = a + b; // both are number
+    const next = a + b;
     a = b;
     b = next;
   }

src/fibRoute.ts

@@ -1,16 +1,26 @@
-// Endpoint for querying the fibonacci numbers
+// src/fibRoute.ts
+import type { Request, Response } from "express";
+import { fibonacci } from "./fib";
 
-const fibonacci = require("./fib");
+export default function fibRoute(req: Request, res: Response): void {
+  const numParam: string | undefined = req.params?.num;
 
-export default (req, res) => {
-  const { num } = req.params;
-
-  const fibN = fibonacci(parseInt(num));
-  let result = `fibonacci(${num}) is ${fibN}`;
+  if (typeof numParam !== "string") {
+    res.status(400).send("Missing route parameter 'num'");
+    return;
+  }
 
-  if (fibN < 0) {
-    result = `fibonacci(${num}) is undefined`;
+  const n = Number.parseInt(numParam, 10);
+  if (Number.isNaN(n)) {
+    res.status(400).send(`Invalid number: "${numParam}"`);
+    return;
   }
 
+  const fibN = fibonacci(n);
+  const result =
+    fibN < 0
+      ? `fibonacci(${n}) is undefined`
+      : `fibonacci(${n}) is ${fibN}`;
+
   res.send(result);
-};
+}