docs(express.json): clarify usage and add route-specific limit example

_includes/api/en/4x/express.json.md

@@ -39,4 +39,4 @@ The following table describes the properties of the optional `options` object.
 | `type`        | This is used to determine what media type the middleware will parse. This option can be a string, array of strings, or a function. If not a function, `type` option is passed directly to the [type-is](https://www.npmjs.org/package/type-is#readme) library and this can be an extension name (like `json`), a mime type (like `application/json`), or a mime type with a wildcard (like `*/*` or `*/json`). If a function, the `type` option is called as `fn(req)` and the request is parsed if it returns a truthy value. | Mixed | `"application/json"` |
 | `verify`      | This option, if supplied, is called as `verify(req, res, buf, encoding)`, where `buf` is a `Buffer` of the raw request body and `encoding` is the encoding of the request. The parsing can be aborted by throwing an error. | Function | `undefined` |
 
-</div>
+</div>

_includes/api/en/4x/express.static.md

@@ -93,3 +93,4 @@ var options = {
 
 app.use(express.static('public', options))
 ```
+

zh-tw/guide/using-middleware.md

@@ -36,66 +36,27 @@ You can also load a series of middleware functions together, which creates a sub
 
 使用 `app.use()` 和 `app.METHOD()` 函數，將應用程式層次的中介軟體連結至 [app object](/{{ page.lang }}/4x/api.html#app) 實例，其中 `METHOD` 是中介軟體函數要處理的 HTTP 要求方法（例如 GET、PUT 或 POST），並採小寫。
 
-This example shows a middleware function with no mount path. The function is executed every time the app receives a request.
+<h2 id='middleware.built-in'>內建中介軟體</h2>
 
-```js
-const express = require('express')
-const app = express()
-
-app.use((req, res, next) => {
-  console.log('Time:', Date.now())
-  next()
-})
-```
-
-This example shows a middleware function mounted on the `/user/:id` path. The function is executed for any type of
-HTTP request on the `/user/:id` path.
+Express has the following built-in middleware functions:
 
-```js
-app.use('/user/:id', (req, res, next) => {
-  console.log('Request Type:', req.method)
-  next()
-})
-```
+- express.json()
+- express.urlencoded()
+- express.static()
 
-This example shows a route and its handler function (middleware system). The function handles GET requests to the `/user/:id` path.
+Here is an example of using the `express.json` middleware with a custom limit:
 
 ```js
-app.get('/user/:id', (req, res, next) => {
-  res.send('USER')
-})
-```
+const express = require('express')
+const app = express()
 
-Here is an example of loading a series of middleware functions at a mount point, with a mount path.
-It illustrates a middleware sub-stack that prints request info for any type of HTTP request to the `/user/:id` path.
+// Apply a 5MB limit for /upload requests
+app.use('/upload', express.json({ limit: '5mb' }))
 
-```js
-app.use('/user/:id', (req, res, next) => {
-  console.log('Request URL:', req.originalUrl)
-  next()
-}, (req, res, next) => {
-  console.log('Request Type:', req.method)
-  next()
-})
+// Use default limit for all other routes
+app.use(express.json())
 ```
 
-Route handlers enable you to define multiple routes for a path. The example below defines two routes for GET requests to the `/user/:id` path. The second route will not cause any problems, but it will never get called because the first route ends the request-response cycle.
-
-本例顯示中介軟體子堆疊，它處理了指向 `/user/:id` 路徑的 GET 要求。
-
-```js
-app.get('/user/:id', (req, res, next) => {
-  console.log('ID:', req.params.id)
-  next()
-}, (req, res, next) => {
-  res.send('User Info')
-})
-
-// handler for the /user/:id path, which prints the user ID
-app.get('/user/:id', (req, res, next) => {
-  res.send(req.params.id)
-})
-```
 
 To skip the rest of the middleware functions from a router middleware stack, call `next('route')` to pass control to the next route.