Source: Jolli-sample-repos/url-shortener Last Updated: 4/8/2026

Overview

Key Design Choices

Stateless REST API - No sessions, each request self-contained

Dual-index Map storage - O(1) lookups for both shortCode and longUrl (deduplication)


// storage.ts:7-8
urls: Map<shortCode, ShortUrl>
longUrlIndex: Map<longUrl, shortCode>

nanoid (6 chars) - 62^6 = 56B combinations, low collision potential.


// generator.ts:4-5
const ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
const nanoid = customAlphabet(ALPHABET, 6);

Zod validation - Type-safe schema validation at API boundary


// validator.ts:3-8
createUrlSchema = z.object({
  longUrl: z.string().url(),
  customCode: z.string().regex(/^[a-zA-Z0-9]+$/).min(4).max(20).optional(),
  expiresAt: z.string().datetime().optional()
});

Trade-offs

Choice	Pro	Con
In-memory Map	Fast, simple	Data loss on restart
nanoid vs UUID	6 chars vs 36	Collision handling needed
No auth	Focus on core features	Production needs auth layer
Vanilla JS	Zero build, instant load	No React features