Gateway as a Service (GaaS)

api.mjs

function createApi(baseUrl, defaults = {}) {
  const callable = () => {}
  callable.url = baseUrl
  return new Proxy(callable, {
    get({ url }, key) {
      const method = key.toUpperCase()
      if (['GET', 'POST', 'PUT', 'DELETE', 'PATCH'].includes(method)) {
        return (data, overrides = {}) => {
          const payload = { method, ...defaults, ...overrides }
          switch (method) {
            case 'GET': {
              if (data) url = `${url}?${new URLSearchParams(data)}`
              break
            }
            case 'POST':
            case 'PUT':
            case 'PATCH': {
              payload.body = JSON.stringify(data)
            }
          }
          return fetch(url, payload).then(d => d.json())
        }
      }
      return createApi(`${url}/${key}`, defaults)
    }
  })
}

export { createApi }

package.json

{
  "scripts": {
    "dev": "wrangler dev --local --port 3000 --inspect false worker.mjs"
  },
  "devDependencies": {
    "wrangler": "^2.0.29"
  }
}

worker.mjs

import { createApi } from './api.mjs'

export default {
  async fetch(request) {
    try {
      const headers = request.headers
      const uri = new URL(request.url)
      const { origin, pathname } = new URL(uri.pathname.substring(1))
      const api = createApi(origin, { headers })
      const payload = await api[pathname][request.method](uri.searchParams)

      return Response.json(payload)
    } catch (error) {
      return Response.json({ error: error.message })
    }
  }
}