Link shortener starter

The code

Two files, exactly what you get in the editor.

import { createServer } from 'node:http'
import { nanoid } from 'nanoid'

const links = new Map<string, string>([['jsdrop', 'https://jsdrop.com']])

const server = createServer(async (req, res) => {
  const url = new URL(req.url ?? '/', 'http://localhost')

  if (req.method === 'POST' && url.pathname === '/shorten') {
    let body = ''
    for await (const chunk of req) body += chunk
    try {
      const target = new URL(JSON.parse(body).url).toString()
      const code = nanoid(7)
      links.set(code, target)
      res.writeHead(201, { 'content-type': 'application/json' })
      return res.end(JSON.stringify({ code, short: `/${code}`, target }))
    } catch {
      res.writeHead(400, { 'content-type': 'application/json' })
      return res.end(JSON.stringify({ error: 'Send JSON like {"url": "https://…"}' }))
    }
  }

  const target = links.get(url.pathname.slice(1))
  if (target) {
    res.writeHead(302, { location: target })
    return res.end()
  }
  res.writeHead(200, { 'content-type': 'text/html; charset=utf-8' })
  res.end(`<h1>Link shortener</h1><p>${links.size} links. Try <a href="/jsdrop">/jsdrop</a>.</p>`)
})

const port = Number(process.env.PORT) || 3000
server.listen(port, () => console.log(`Shortener on port ${port}`))

{
  "name": "link-shortener",
  "private": true,
  "type": "module",
  "dependencies": {
    "nanoid": "^5.1.0"
  }
}