preface

For a div engineer with a dream, the back end is also a dream direction. For those who are new to the back end, using frameworks will undoubtedly reduce the cost of learning. Both Express and KOA are well-known backend frameworks in the industry. Here we will take a look at Express.

The body of the

Express. XXX related API

  • express.json()

Normally, you can’t get the request body directly through request.body because the request data is transmitted as a stream. So when you get it, you also get it by stream

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

app.use('/', (request, response, next) => {
  response.send('hi')
  request.on('data', (chunk) => {
    console.log(chunk.toString())
  })
  next()
})
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This is a bit of a hassle, so you need to use express.json() to help convert to JSON objects

app.use(express.json())

app.use('/', (request, response, next) => {
  response.send('hi')
  console.log(request.body)
  next()
})
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  • express.static('yyy')

The API will first look for the corresponding file in the yyy directory, if not, then execute next to match the other conditional logic:

If (have file){sendFile(' XXX ')}else{next()}Copy the code

App related API

  • app.locals

Set. Unlike app.set, app.locals sets values that can be used in multiple middleware

  • app.set / app.get

Use app.set(‘env’, ‘XXX ‘) to set env to XXX

Use app.get(‘env’) to get the set value

Typical use: app.set(‘case sensitive routing’, true). This parameter is set to false

Request the relevant API

  • request.get()

Used to get the request header

  • request.param('name')

Gets the routing and query string sections

  • request.range()

Limits whether multithreaded downloads are supported and the range of downloads

The response related API

  • response.send() / response.sendFile()

Response content/response file

  • response.status()

Example Set the HTTP status code

  • response.location

Use response.redirect(‘/ XXX ‘) instead. Redirect (‘/ XXX ‘)

The router sample

//app.js const express = require('express') const app = express() const user = require('./routers/user') App.use ('/user', user) app.listen(3000, () => {console.log(' listening on port 3000 ')})Copy the code
// routers/user.js
const express = require('express')
const router = express.Router()

router.get('/', (req, res) => {
  res.send('/user')
})
router.get('/:id', (req, res) => {
  res.send('/user/:id')
})
router.get('/:id/edit', (req, res) => {
  res.send('/user/:id/edit  ')
})

module.exports = router
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