README.md

Express controllers/routes conventions

HTTP Verb	Path	Controller#Action	Used for
GET	/photos	photos#index	display a list of all photos
PUT	/photos/:id/valid OR /photos/valid	photos#validate	tell whether the passed data are valid (204 or 422)
HEAD	/photos/:id OR /photos?people=Sam	photos#exist	tell whether that photo exists (204 or 404)
GET	/photos/new	photos#new	return an HTML form for creating a new photo
POST	/photos	photos#create	create a new photo
GET	/photos/:id	photos#show	display a specific photo
GET	/photos/:id/edit	photos#edit	return an HTML form for editing a photo
PATCH/PUT	/photos/:id	photos#update	update a specific photo
DELETE	/photos/:id	photos#destroy	delete a specific photo

see: https://guides.rubyonrails.org/routing.html#crud-verbs-and-actions

app.js

const express = require('express')
const app = express()

app.use('/photos', require ('./routes/photos.js'))

app.listen(3000)

controllers\photos.js

exports.index = (req, res, next) => {/*...*/}

exports.validate = (req, res, next) => {/*...*/}

exports.exist = (req, res, next) => {/*...*/}

exports.new = (req, res, next) => {/*...*/}
exports.create = (req, res, next) => {/*...*/}

exports.show = (req, res, next) => {/*...*/}

exports.edit = (req, res, next) => {/*...*/}
exports.update = (req, res, next) => {/*...*/}

exports.destroy = (req, res, next) => {/*...*/}

routes\photos.js

const express = require('express')
const router = express.Router()

const controller = require('../controllers/photos.js');

router.get('/', controller.index);

router.put('/valid', controller.validate)
router.put('/:id/valid', controller.validate)

router.head('/:id', controller.exist)

router.get('/new', controller.new);
router.post('/', controller.create);

router.get('/:id', controller.show);

router.get('/:id/edit', controller.edit);
router.put('/:id', controller.update);

router.delete('/:id', controller.destroy);

module.exports = router

As HTML <form>'s method can only be GET/POST, method-override can be handy :

// app.js
const methodOverride = require('method-override')

app.use(methodOverride('_method'))

app.delete('/cats/:id', function () {});

<form action="/cats/123?_method=DELETE" method="POST">
  ...
</form>