1. Install initialization and Get methods

  • The first part of the Express official website is installed and initialized

The introduction of the code

Const express = require('express') // introduce express const app = express() // instantiate const port = 3000 // set port // set URL with get // app.get('/', (req, res) => res.send('Hello World! ') // App.listen (port, () => console.log(' Example app listening on port ${port}! `))Copy the code

Nodeapp.js starts localhost:3000 and Cannot GET/because the URL routing and HTTP request were not processed

App.get ('/', (req, res) => res.send('Hello World! '))Copy the code

Restart Node app.js and access it on port 3000

Print Hello World!

2. Middleware POST delete

  • Middleware is a custom extension of Express functionalityPerform a specific action before a request or response

App.use (express.json()) // Extend express functionality with JSON middleware

  • Test the POST function
Const express = require('express') // introduce express const app = express() // instantiate const port = 3000 // set port App.use (express.json()) // Extend express functionality with JSON middleware // set url with get // The front part is the root route and the back part is the callback function and sends data to the client app.get('/', (req, res) => res.send('Hello World! ')) app. Post ('/', (the req, res) = > {/ / post a new request to the console. The log (' received the request body: 'the req. Body); Res.status (201).send() // Set the request success status code 201}) () => console.log(`Example app listening on port ${port}! `))Copy the code

  • Using Postman pictures can not paste

    Choose the post

    The address is localhost:3000

    Body to select raw

    • Note The postman data type must be SET to JSON; otherwise, the data cannot be retrieved after being sent

    {“name”:” FHJ “}

Then click Send to see the status code 201 and the console prints out the JSON content

3. Put Updates data

App. Put ("/" id ", (the req, res) = > {/ / update the data to the console. The log (" receipt of a request parameter, id is: ", the req. Params. Id); Console. log(" Received request body :",req.body); res.send(); })Copy the code

It is important to restart the service after the change

Postman select PUT and fill localhost:3000/6 select Body raw json {“name”:” FHJ “}

Click Send to get the ID and JSON data

4. Delete Deletes data

App.delete ("/:id",(req,res)=>{// Delete data console.log(" received request parameters, id: ", req.params.id); res.status(204).send() })Copy the code
  • Restart the service CTR +c node app.js
  • So let’s test postman and say delete and say localhost:3000/6
  • Inside the body, select None and hit Send
  • Display 204 Console prints received request parameter, id: 6

Real Express projects will include multiple apis

  • Use the article example to create a/POST child route
  • Create post.js on routes
const express = require('express'); // Router instance // Copy the previous four requests and modify the content // set the URL with get // The first part is the root route and the second part is the callback function and send data to the client route.get('/', (req, Res) = > res. Send ({id: 1, the title: "express introductory tutorial"})) / / sample data route. The post ('/', (the req, res) = > {/ / post a new request Console. log(' Save article :',req.body); res.status(201).send({id:2, ... Req.body}) // set request success status code 201}) route.put("/:id", (req,res)=>{// Update data console.log(" received request parameters, article ID: ", req.params.id); Console. log(" Received request body, new article content :",req.body); res.send({id:req.params.id, ... req.body}); }) route.delete("/:id",(req,res)=>{// delete data console.log(" received request parameters, article ID: ", req.params.id); res.status(204).send() }) module.exports = route; // Export routing variablesCopy the code
  • You need to import this in app.js
const post = require('./routes/post')
app.use("/post",post)
Copy the code
  • Post localhost:3000/post

And then I’m going to write some JSON data and I’m going to hit Send to get the ID and the JSON data

6. Simplify

  • Create index.js under routes
const post = require("./post"); Exports =(app) => {// exports a function that receives app object mounts app.use("/post",post)}Copy the code
  • How to use app.js?
const routes = require("./routes")
routes(app)
Copy the code

7. See here

  • It may take longer than 3 minutes, but it should be very rewarding