router

Simple middleware-style router

Installation

$ npm install router

API

var finalhandler = require('finalhandler')
var http         = require('http')
var Router       = require('router')

var router = Router()
router.get('/', function (req, res) {
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')
  res.end('Hello World!')
})

var server = http.createServer(function (req, res) {
  router(req, res, finalhandler(req, res))
})

server.listen(3000)

This module is currently an extracted version from the Express project, but with the main change being it can be used with a plain http.createServer object or other web frameworks by removing Express-specific API calls.

Middleware

This router is based on connect-style middleware. The middleware is added as a "stack" and a request will execute each one. Middleware is just a function which takes a request object (req), a response object (res) and a next() function which will call the next middleware on the stack.

router.use(function (req, res, next) {
  // called first
  next()
})

router.use(function (req, res, next) {
  // called second
  next()
})

The use function is just one way to add middleware to the stack.

Error handling middleware

When an error is thrown in your middleware, router will look for special error handling middleware. Error handling middleware differs from normal middleware in that it takes four parameters, the standard req, res, and next along with an added err parameter.

To throw an error, either use the throw language construct, or pass an error object to the next() function.

router.use(function (req, res, next) {
  // called first
  next(new Error('Something exploded'))
})

router.use(function (err, req, res, next) {
  // called second
  console.error(err.stack)
})

Promises in middleware

The router supports some basic ES6 Promise functionality in middleware. If a promise is rejected, next() will automatically be called with an error.

Unless you reject the promise, next() must still be called.

router.use(function (req, res, next) {
  // called first
  return new Promise(function (resolve, reject) {
    resolve()
    next()
  })
})

router.use(function (req, res, next) {
  // called second
  return new Promise(function (resolve, reject) {
    reject(new Error('Something exploded'))
  })
})

router.use(function (error, req, res, next) {
  // called third
  console.error(err.stack)
})

When you call next() it will also return a promise that resolves when the middleware stack is exhausted. The next() promise is also rejected when there is an error.

router.use(function (req, res, next) {
  // called first
  var start = new Date()
  next().then(function () {
    // called third
    var ms = new Date() - start
    console.log('Response time %s milliseconds', ms)
  })
})

router.use(function (req, res, next) {
  // called second
  res.end('done')
  next()
})

Router(options)

Options

• strict - When false trailing slashes are optional (default: false)
• caseSensitive - When true the routing will be case sensitive. (default: false)
• mergeParams - When true any req.params passed to the router will be merged into the router's req.params. (default: false) (example)

Returns a function with the signature router(res, res, callback) where callback([err]) must be provided to handle errors and fall-through from not handling requests.

router.use([path], ...middleware)

Use the given middleware function for all http methods on the given path, defaulting to the root path.

router does not automatically see use as a handler. As such, it will not consider it one for handling OPTIONS requests.

• Note: If a path is specified, that path is stripped from the start of req.url.

router.use(function (req, res, next) {
  // do your things

  // continue to the next middleware
  // the request will stall if this is not called
  next()

  // note: be careful calling `next` if you have begun writing to the response
})

router[method](path, ...[middleware], handler)

The http methods provide the routing functionality in router.

These are functions which you can directly call on the router to register a new handler for the method at a specified path.

// handle a `GET` request
router.get('/', function (req, res) {
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')
  res.end('Hello World!')
})

Additional middleware may be given before the handler. These middleware behave exactly as normal with one exception: they may invoke next('route'). Calling next('route') bypasses the remaining middleware and handler for this route, passing the request on to the next route.

router.param(name, param_middleware)

Maps the specified path parameter name to a specialized param-capturing middleware.

This function positions the middleware in the same stack as .use.

Parameter mapping is used to provide pre-conditions to routes which use normalized placeholders. For example a :user_id parameter could automatically load a user's information from the database without any additional code:

router.param('user_id', function (req, res, next, id) {
  User.find(id, function (err, user) {
    if (err) {
      return next(err)
    } else if (!user) {
      return next(new Error('failed to load user'))
    }
    req.user = user

    // continue processing the request
    next()
  })
})

router.route(path)

Creates an instance of a single Route for the given path. (See Router.Route below)

Routes can be used to handle http methods with their own, optional middleware.

Using router.route(path) is a recommended approach to avoiding duplicate route naming and thus typo errors.

var api = router.route('/api/')

Router.Route(path)

Represents a single route as an instance that can be used can be used to handle http methods with it's own, optional middleware.

route[method](handler)

These are functions which you can directly call on a route to register a new handler for the method on the route.

// handle a `GET` request
var status = router.route('/status')

status.get(function (req, res) {
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')
  res.end('All Systems Green!')
})

route.all(handler)

Adds a handler for all HTTP methods to this route.

The handler can behave like middleware and call next to continue processing rather than responding.

router.route('/')
.all(function (req, res, next) {
  next()
})
.all(check_something)
.get(function (req, res) {
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')
  res.end('Hello World!')
})

Examples

// import our modules
var http         = require('http')
var Router       = require('router')
var finalhandler = require('finalhandler')
var compression  = require('compression')
var bodyParser   = require('body-parser')

// store our message to display
var message = "Hello World!"

// initialize the router & server and add a final callback.
var router = Router()
var server = http.createServer(function onRequest(req, res) {
  router(req, res, finalhandler(req, res))
})

// use some middleware and compress all outgoing responses
router.use(compression())

// handle `GET` requests to `/message`
router.get('/message', function (req, res) {
  res.statusCode = 200
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')
  res.end(message + '\n')
})

// create and mount a new router for our API
var api = Router()
router.use('/api/', api)

// add a body parsing middleware to our API
api.use(bodyParser.json())

// handle `PATCH` requests to `/api/set-message`
api.patch('/set-message', function (req, res) {
  if (req.body.value) {
    message = req.body.value

    res.statusCode = 200
    res.setHeader('Content-Type', 'text/plain; charset=utf-8')
    res.end(message + '\n')
  } else {
    res.statusCode = 400
    res.setHeader('Content-Type', 'text/plain; charset=utf-8')
    res.end('Invalid API Syntax\n')
  }
})

// make our http server listen to connections
server.listen(8080)

You can get the message by running this command in your terminal, or navigating to 127.0.0.1:8080 in a web browser.

curl http://127.0.0.1:8080

You can set the message by sending it a PATCH request via this command:

curl http://127.0.0.1:8080/api/set-message -X PATCH -H "Content-Type: application/json" -d '{"value":"Cats!"}'

Example using mergeParams

var http         = require('http')
var Router       = require('router')
var finalhandler = require('finalhandler')

// this example is about the mergeParams option
var opts = { mergeParams: true }

// make a router with out special options
var router = Router(opts)
var server = http.createServer(function onRequest(req, res) {

  // set something to be passed into the router
  req.params = { type: 'kitten' }

  router(req, res, finalhandler(req, res))
})

router.get('/', function (req, res) {
  res.statusCode = 200
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')

  // with respond with the the params that were passed in
  res.end(req.params.type + '\n')
})

// make another router with our options
var handler = Router(opts)

// mount our new router to a route that accepts a param
router.use('/:path', handler)

handler.get('/', function (req, res) {
  res.statusCode = 200
  res.setHeader('Content-Type', 'text/plain; charset=utf-8')

  // will respond with the param of the router's parent route
  res.end(path + '\n')
})

// make our http server listen to connections
server.listen(8080)

Now you can get the type, or what path you are requesting:

curl http://127.0.0.1:8080
> kitten
curl http://127.0.0.1:8080/such_path
> such_path

License

MIT