DRAFT: "AutoRouter" to reduce router initialization boilerplate

[kwhitley]

Description

Adds flow(router: Router, options?: FlowOptions): Response to reduce boilerplate. This function makes the following assumptions (with override controls):

• Default response formatter as json
• Includes default 404 handler on missed route
• Includes default 500 error handler on uncaught errors

// BEFORE/WITHOUT FLOW
import { Router, json, error } from 'itty-router'

const router = Router()

router
  .get('/my-items', () => [1, 2, 3])
  .get('*', () => error(404))

export default {
  fetch: (...args) => router
                        .handle(...args)
                        .then(json)
                        .catch(error)
}

// AFTER/WITH FLOW
import { Router, flow } from 'itty-router'

const router = Router()

router.get('/my-items', () => [1, 2, 3])

export default {
  fetch: flow(router)
}

// or even

export default flow(router)

// WITH FLOW, OVERRIDES (including CORS)
import { Router, flow, error } from 'itty-router'

const router = Router()

router.get('/my-items', () => [1, 2, 3])

export default {
  fetch: flow(router, {
    cors: true,
    notFound: (req) => error(404, `The path "${req.url}" was not found.`),
  })
}

API (options)

Option Name	Default	Valid Choices
cors	false	false (off/ignore), true (default createCors()), CorsOptions
format	json	false (off/ignore), Function<Response>
errors	error	false (off/ignore), Function<Response>
notFound	() => error(404)	false (off/ignore), Function<Response>

Type of Change (select one and follow subtasks)

• [ ] Documentation (README.md)
• [ ] Maintenance or repo-level work (e.g. linting, build, tests, refactoring, etc.)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
  • [x] I have included test coverage
• [ ] Breaking change (fix or feature that would cause existing functionality/userland code to not work as expected)
  • [ ] Explain why a breaking change is necessary:
• [x] This change requires (or is) a documentation update
  • [ ] I have added necessary local documentation (if appropriate)
  • [ ] I have added necessary itty.dev documentation (if appropriate)

[kwhitley]

Adding to the discussion here... flow has been shelved for an arguably better router approach. Notes to follow.

[kwhitley]

Killed in favor of #222