Use koa to mock data and set cross domain issues

Installation and use process

install

npm i -S koa
npm i -S koa-router
npm i -S koa-bodyparser

Import the following methods ;

const Koa = require('koa');
const router = require('koa-router')();
// post request , Request body required , At this time, you need to install  koa-bodyparser, It can be parsed from body The data transmitted from it 
const bodyparser = require('koa-bodyparser');
const fs = require('fs');// fs The file system is nodejs Built in , No installation required .

app.use(bodyparser())

Print log

//  When the service period is accessed , Print out the request type and the requested url;
app.use(async (ctx, next) => {
    
    console.log(`${
      ctx.request.method} ${
      ctx.request.url}`);
    await next();
});

Interface

// post request 
router.post('/api/postUser', async (ctx, next) => {
    
    // ctx.request.body  Requested parameters 
    const {
     username, password } = ctx.request.body

    if (!username || !password) {
    
        ctx.response.body = {
     Msg: " User name or password cannot be empty ", ResultCode: 0}
        return;
    }

    let ret = null
    try {
    
        ret = await fs.readFileSync('./user.json')
        ret = JSON.parse(ret.toString())
    } catch (error) {
     
        ret = [] 
    }

    ret.push({
      username, password })
    ctx.response.body = {
     Msg: " Registered successfully ",  ResultCode: 1 }

    try {
    
        fs.writeFileSync('./user.json', JSON.stringify(ret))
        ctx.response.body = {
     Msg: `${
      username} Registered successfully `, ResultCode: 1}
    } catch (err) {
    
        if (err) ctx.response.body = {
     Msg: " Registration failed , Please re submit ", ResultCode: 0}
    }
});

// get request 
router.get('/api/getUser', async (ctx, next) => {
    
    ctx.response.body = {
    
        name: ' Zhang San ',
        phone: '15111111111'
    }
});

Add router Middleware , And setting the service period host And port

app.use(router.routes());

const host = '131.122.2.55';
const port = '2255';

app.listen(port, host, () => {
    
    console.log(`http://${
      host}:${
      port}`);
});

Call in project :

 axios.post('http://131.122.2.55:2255/api/postUser',{
    username: " Zhang San 12"}).then(ret => {
    
   console.log(ret);
 })

 axios.get('http://131.122.2.55:2255/api/getUser').then(ret => {
    
   console.log(ret);
 })

The result is shown in Fig.

To solve the cross domain
install npm i -S koa2-cors

const cors = require('koa2-cors');

app.use(
    cors({
    
        origin: function (ctx) {
     // Set to allow requests from the specified domain name 
             return '*'; 
            // if (ctx.url === '/choose-city') { return '*'; //  Allow requests from all domain names  }
            // return 'http://localhost:8080'; //  Only http://localhost:8080 This domain name request 
        },
        maxAge: 5, // Specify the validity period of this pre inspection request , The unit is in seconds .
        credentials: true, // Is it allowed to send Cookie
        allowMethods: ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'], // Set the allowed HTTP Request method '
        allowHeaders: ['Content-Type', 'Authorization', 'Accept'], // Set all header information fields supported by the server 
        exposeHeaders: ['WWW-Authenticate', 'Server-Authorization'] // Set get other custom fields 
    })
);

Run again node mock.js The results are as follows

Complete code The results are shown in the figure below , The new data is stored locally user.json In the document

Please stamp the complete code