Express API

1import express, { Request, Response, NextFunction } from "express";
2 
3// Type definitions
4interface User {
5  id: number;
6  name: string;
7  email: string;
8}
9 
10interface CreateUserBody {
11  name: string;
12  email: string;
13}
14 
15// Typed request with body
16interface TypedRequest<T> extends Request {
17  body: T;
18}
19 
20// In-memory storage
21const users: User[] = [
22  { id: 1, name: "Alice", email: "alice@example.com" },
23  { id: 2, name: "Bob", email: "bob@example.com" },
24];
25 
26// Express app
27const app = express();
28app.use(express.json());
29 
30// Error handler middleware
31function errorHandler(
32  err: Error,
33  req: Request,
34  res: Response,
35  next: NextFunction
36): void {
37  console.error(err.stack);
38  res.status(500).json({ error: err.message });
39}
40 
41// Routes
42app.get("/api/users", (req: Request, res: Response) => {
43  res.json(users);
44});
45 
46app.get("/api/users/:id", (req: Request, res: Response) => {
47  const id = parseInt(req.params.id, 10);
48  const user = users.find((u) => u.id === id);
49 
50  if (!user) {
51    res.status(404).json({ error: "User not found" });
52    return;
53  }
54 
55  res.json(user);
56});
57 
58app.post(
59  "/api/users",
60  (req: TypedRequest<CreateUserBody>, res: Response) => {
61    const { name, email } = req.body;
62 
63    if (!name || !email) {
64      res.status(400).json({ error: "Name and email are required" });
65      return;
66    }
67 
68    const newUser: User = {
69      id: users.length + 1,
70      name,
71      email,
72    };
73 
74    users.push(newUser);
75    res.status(201).json(newUser);
76  }
77);
78 
79app.delete("/api/users/:id", (req: Request, res: Response) => {
80  const id = parseInt(req.params.id, 10);
81  const index = users.findIndex((u) => u.id === id);
82 
83  if (index === -1) {
84    res.status(404).json({ error: "User not found" });
85    return;
86  }
87 
88  users.splice(index, 1);
89  res.status(204).send();
90});
91 
92app.use(errorHandler);
93 
94const PORT = 3000;
95app.listen(PORT, () => {
96  console.log(`API server running at http://localhost:${PORT}`);
97});