lint: use es6 everywhere besides legacy api docs

closes #470

_includes/api/en/5x/app-all.md

@@ -11,7 +11,7 @@ The following callback is executed for requests to `/secret` whether using
 GET, POST, PUT, DELETE, or any other HTTP request method:
 
 ```js
-app.all('/secret', function (req, res, next) {
+app.all('/secret', (req, res, next) => {
   console.log('Accessing the secret section ...')
   next() // pass control to the next handler
 })

_includes/api/en/5x/app-delete-method.md

@@ -8,7 +8,7 @@ For more information, see the [routing guide](/guide/routing.html).
 #### Example
 
 ```js
-app.delete('/', function (req, res) {
+app.delete('/', (req, res) => {
   res.send('DELETE request to homepage')
 })
 ```

_includes/api/en/5x/app-get-method.md

@@ -9,7 +9,7 @@ For more information, see the [routing guide](/guide/routing.html).
 #### Example
 
 ```js
-app.get('/', function (req, res) {
+app.get('/', (req, res) => {
   res.send('GET request to homepage')
 })
 ```

_includes/api/en/5x/app-mountpath.md

@@ -12,7 +12,7 @@ const express = require('express')
 const app = express() // the main app
 const admin = express() // the sub app
 
-admin.get('/', function (req, res) {
+admin.get('/', (req, res) => {
   console.log(admin.mountpath) // /admin
   res.send('Admin Homepage')
 })
@@ -29,13 +29,13 @@ patterns it is mounted on, as shown in the following example.
 ```js
 const admin = express()
 
-admin.get('/', function (req, res) {
+admin.get('/', (req, res) => {
   console.log(admin.mountpath) // [ '/adm*n', '/manager' ]
   res.send('Admin Homepage')
 })
 
 const secret = express()
-secret.get('/', function (req, res) {
+secret.get('/', (req, res) => {
   console.log(secret.mountpath) // /secr*t
   res.send('Admin Secret')
 })

_includes/api/en/5x/app-onmount.md

@@ -16,12 +16,12 @@ For details, see [Application settings](/en/5x/api.html#app.settings.table).
 ```js
 const admin = express()
 
-admin.on('mount', function (parent) {
+admin.on('mount', (parent) => {
   console.log('Admin Mounted')
   console.log(parent) // refers to the parent app
 })
 
-admin.get('/', function (req, res) {
+admin.get('/', (req, res) => {
   res.send('Admin Homepage')
 })
 

_includes/api/en/5x/app-param.md

@@ -7,9 +7,9 @@ If `name` is an array, the `callback` trigger is registered for each parameter d
 For example, when `:user` is present in a route path, you may map user loading logic to automatically provide `req.user` to the route, or perform validations on the parameter input.
 
 ```js
-app.param('user', function (req, res, next, id) {
+app.param('user', (req, res, next, id) => {
   // try to get the user details from the User model and attach it to the request object
-  User.find(id, function (err, user) {
+  User.find(id, (err, user) => {
     if (err) {
       next(err)
     } else if (user) {
@@ -27,17 +27,17 @@ Param callback functions are local to the router on which they are defined. They
 All param callbacks will be called before any handler of any route in which the param occurs, and they will each be called only once in a request-response cycle, even if the parameter is matched in multiple routes, as shown in the following examples.
 
 ```js
-app.param('id', function (req, res, next, id) {
+app.param('id', (req, res, next, id) => {
   console.log('CALLED ONLY ONCE')
   next()
 })
 
-app.get('/user/:id', function (req, res, next) {
+app.get('/user/:id', (req, res, next) => {
   console.log('although this matches')
   next()
 })
 
-app.get('/user/:id', function (req, res) {
+app.get('/user/:id', (req, res) => {
   console.log('and this matches too')
   res.end()
 })
@@ -52,17 +52,17 @@ and this matches too
 ```
 
 ```js
-app.param(['id', 'page'], function (req, res, next, value) {
+app.param(['id', 'page'], (req, res, next, value) => {
   console.log('CALLED ONLY ONCE with', value)
   next()
 })
 
-app.get('/user/:id/:page', function (req, res, next) {
+app.get('/user/:id/:page', (req, res, next) => {
   console.log('although this matches')
   next()
 })
 
-app.get('/user/:id/:page', function (req, res) {
+app.get('/user/:id/:page', (req, res) => {
   console.log('and this matches too')
   res.end()
 })

_includes/api/en/5x/app-post-method.md

@@ -8,7 +8,7 @@ For more information, see the [routing guide](/guide/routing.html).
 #### Example
 
 ```js
-app.post('/', function (req, res) {
+app.post('/', (req, res) => {
   res.send('POST request to homepage')
 })
 ```

_includes/api/en/5x/app-put-method.md

@@ -7,7 +7,7 @@ Routes HTTP PUT requests to the specified path with the specified callback funct
 #### Example
 
 ```js
-app.put('/', function (req, res) {
+app.put('/', (req, res) => {
   res.send('PUT request to homepage')
 })
 ```

_includes/api/en/5x/app-render.md

@@ -15,11 +15,11 @@ cache view during development; view caching is enabled in production by default.
 </div>
 
 ```js
-app.render('email', function (err, html) {
+app.render('email', (err, html) => {
   // ...
 })
 
-app.render('email', { name: 'Tobi' }, function (err, html) {
+app.render('email', { name: 'Tobi' }, (err, html) => {
   // ...
 })
 ```

_includes/api/en/5x/app-route.md

@@ -7,14 +7,14 @@ Use `app.route()` to avoid duplicate route names (and thus typo errors).
 const app = express()
 
 app.route('/events')
-  .all(function (req, res, next) {
+  .all((req, res, next) => {
     // runs for all HTTP verbs first
     // think of it as route specific middleware!
   })
-  .get(function (req, res, next) {
+  .get((req, res, next) => {
     res.json({})
   })
-  .post(function (req, res, next) {
+  .post((req, res, next) => {
     // maybe add a new event...
   })
 ```

_includes/api/en/5x/app-router.md

@@ -7,7 +7,7 @@ const express = require('express')
 const app = express()
 const router = app.router
 
-router.get('/', function (req, res) {
+router.get('/', (req, res) => {
   res.send('hello world')
 })
 

_includes/api/en/5x/app-settings.md

@@ -263,7 +263,7 @@ app.set('trust proxy', ['loopback', 'linklocal', 'uniquelocal'])
   Custom trust implementation. Use this only if you know what you are doing.
 
 ```js
-app.set('trust proxy', function (ip) {
+app.set('trust proxy', (ip) => {
   if (ip === '127.0.0.1' || ip === '123.123.123.123') return true // trusted IPs
   else return false
 })
@@ -308,7 +308,7 @@ The [express.static](#express.static) middleware ignores these settings.
   <td markdown="1">Custom ETag function implementation. Use this only if you know what you are doing.
 
 ```js
-app.set('etag', function (body, encoding) {
+app.set('etag', (body, encoding) => {
   return generateHash(body, encoding) // consider the function is defined
 })
 ```

_includes/api/en/5x/app-use.md

@@ -16,7 +16,7 @@ Since `path` defaults to "/", middleware mounted without a path will be executed
 For example, this middleware function will be executed for _every_ request to the app:
 
 ```js
-app.use(function (req, res, next) {
+app.use((req, res, next) => {
   console.log('Time: %d', Date.now())
   next()
 })
@@ -37,12 +37,12 @@ Middleware functions are executed sequentially, therefore the order of middlewar
 
 ```js
 // this middleware will not allow the request to go beyond it
-app.use(function (req, res, next) {
+app.use((req, res, next) => {
   res.send('Hello World')
 })
 
 // requests will never reach this route
-app.get('/', function (req, res) {
+app.get('/', (req, res) => {
   res.send('Welcome')
 })
 ```
@@ -54,7 +54,7 @@ Error-handling middleware always takes _four_ arguments.  You must provide four
 Define error-handling middleware functions in the same way as other middleware functions, except with four arguments instead of three, specifically with the signature `(err, req, res, next)`):
 
 ```js
-app.use(function (err, req, res, next) {
+app.use((err, req, res, next) => {
   console.error(err.stack)
   res.status(500).send('Something broke!')
 })
@@ -83,7 +83,7 @@ mounting middleware.
 This will match paths starting with `/abcd`:
 
 ```js
-app.use('/abcd', function (req, res, next) {
+app.use('/abcd', (req, res, next) => {
   next()
 })
 ```
@@ -97,31 +97,31 @@ app.use('/abcd', function (req, res, next) {
 This will match paths starting with `/abcd` and `/abd`:
 
 ```js
-app.use('/abc?d', function (req, res, next) {
+app.use('/abc?d', (req, res, next) => {
   next()
 })
 ```
 
 This will match paths starting with `/abcd`, `/abbcd`, `/abbbbbcd`, and so on:
 
 ```js
-app.use('/ab+cd', function (req, res, next) {
+app.use('/ab+cd', (req, res, next) => {
   next()
 })
 ```
 
 This will match paths starting with `/abcd`, `/abxcd`, `/abFOOcd`, `/abbArcd`, and so on:
 
 ```js
-app.use('/ab*cd', function (req, res, next) {
+app.use('/ab*cd', (req, res, next) => {
   next()
 })
 ```
 
 This will match paths starting with `/ad` and `/abcd`:
 
 ```js
-app.use('/a(bc)?d', function (req, res, next) {
+app.use('/a(bc)?d', (req, res, next) => {
   next()
 })
 ```
@@ -135,7 +135,7 @@ app.use('/a(bc)?d', function (req, res, next) {
 This will match paths starting with `/abc` and `/xyz`:
 
 ```js
-app.use(/\/abc|\/xyz/, function (req, res, next) {
+app.use(/\/abc|\/xyz/, (req, res, next) => {
   next()
 })
 ```
@@ -149,7 +149,7 @@ app.use(/\/abc|\/xyz/, function (req, res, next) {
 This will match paths starting with `/abcd`, `/xyza`, `/lmn`, and `/pqr`:
 
 ```js
-app.use(['/abcd', '/xyza', /\/lmn|\/pqr/], function (req, res, next) {
+app.use(['/abcd', '/xyza', /\/lmn|\/pqr/], (req, res, next) => {
   next()
 })
 ```
@@ -184,7 +184,7 @@ Even though the examples are for `app.use()`, they are also valid for `app.use()
 You can define and mount a middleware function locally.
 
 ```js
-app.use(function (req, res, next) {
+app.use((req, res, next) => {
   next()
 })
 ```
@@ -193,7 +193,7 @@ A router is valid middleware.
 
 ```js
 const router = express.Router()
-router.get('/', function (req, res, next) {
+router.get('/', (req, res, next) => {
   next()
 })
 app.use(router)
@@ -202,7 +202,7 @@ app.use(router)
 An Express app is valid middleware.
 ```js
 const subApp = express()
-subApp.get('/', function (req, res, next) {
+subApp.get('/', (req, res, next) => {
   next()
 })
 app.use(subApp)
@@ -218,12 +218,12 @@ You can specify more than one middleware function at the same mount path.
 
 ```js
 const r1 = express.Router()
-r1.get('/', function (req, res, next) {
+r1.get('/', (req, res, next) => {
   next()
 })
 
 const r2 = express.Router()
-r2.get('/', function (req, res, next) {
+r2.get('/', (req, res, next) => {
   next()
 })
 
@@ -240,12 +240,12 @@ Use an array to group middleware logically.
 
 ```js
 const r1 = express.Router()
-r1.get('/', function (req, res, next) {
+r1.get('/', (req, res, next) => {
   next()
 })
 
 const r2 = express.Router()
-r2.get('/', function (req, res, next) {
+r2.get('/', (req, res, next) => {
   next()
 })
 
@@ -265,13 +265,13 @@ function mw1 (req, res, next) { next() }
 function mw2 (req, res, next) { next() }
 
 const r1 = express.Router()
-r1.get('/', function (req, res, next) { next() })
+r1.get('/', (req, res, next) => { next() })
 
 const r2 = express.Router()
-r2.get('/', function (req, res, next) { next() })
+r2.get('/', (req, res, next) => { next() })
 
 const subApp = express()
-subApp.get('/', function (req, res, next) { next() })
+subApp.get('/', (req, res, next) => { next() })
 
 app.use(mw1, [mw2, r1, r2], subApp)
 ```

_includes/api/en/5x/app.md

@@ -7,7 +7,7 @@ Create it by calling the top-level `express()` function exported by the Express
 const express = require('express')
 const app = express()
 
-app.get('/', function (req, res) {
+app.get('/', (req, res) => {
   res.send('hello world')
 })
 

_includes/api/en/5x/express.static.md

@@ -79,7 +79,7 @@ const options = {
   index: false,
   maxAge: '1d',
   redirect: false,
-  setHeaders: function (res, path, stat) {
+  setHeaders (res, path, stat) {
     res.set('x-timestamp', Date.now())
   }
 }

_includes/api/en/5x/req-app.md

@@ -14,7 +14,7 @@ app.get('/viewdirectory', require('./mymiddleware.js'))
 
 ```js
 // mymiddleware.js
-module.exports = function (req, res) {
-  res.send('The views directory is ' + req.app.get('views'))
+module.exports = (req, res) => {
+  res.send(`The views directory is ${req.app.get('views')}`)
 }
 ```