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Mode 5 of 5· +200 XP

Build: Augment Express Request with Custom Properties

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◆ Before you start

Prerequisites

TypeScript 5+Required
Any TypeScript project

📝

Step 1 of 1

Augment Express Request with Custom Properties

Add typed user and session properties to Express Request using module augmentation.

Tasks

Create express.d.ts that adds user to Request

Create global.d.ts for window.analytics

Create asset declarations for .svg, .css

Verify typed access to augmented properties

🎯 What You'll Learn

▸Use declare module to augment existing packages
▸Extend interfaces in .d.ts files
▸Declare global Window extensions

Code

TypeScriptsrc/types/express.d.ts
1 import 'express';
2  
3 declare module 'express' {
4   interface Request {
5     user?: {
6       id: string;
7       email: string;
8       role: 'admin' | 'user' | 'guest';
9     };
10     session?: {
11       token: string;
12       expiresAt: Date;
13     };
14     requestId?: string;
15   }
16 }

💡 Pro Tips

▸Must import something from the module you augment (makes it a module, not a script)
▸Place .d.ts files in src/types/ and include in tsconfig

Expected Output

req.user is typed; window.analytics.track compiles; SVG imports don't error

Discussion