Learn Node.js from scratch

url module

1.parse method
2. format method
3. resolve method

Events module (event-driven)

The path module

Summarize

url module

1.parse method

//test02.js
import http from 'http'
import url from 'url'
const parseUrl = url.parse('https://www.baidu.com/news?name=朱葛亮&age=18#helloworld')
console.log(parseUrl)
http.createServer((req, res) => {
    res.writeHead(200, {'Content-Type': 'text/html; charset=utf-8'})
    res.write('Hello, hello world!')
    res.end()
}).listen(3000)
console.log('My server is running at http://localhost:3000')

Parse the URL address and obtain a parsed URL details object, including protocol, domain name, path, port, query parameters, hash and other information.

The second parameter is a boolean value, which defaults to false. If true is passed, the query will be converted to an object.

const parseUrl = url.parse('https://www.baidu.com/news?name=朱葛亮&age=18#helloworld', true)
console.log(parseUrl)

2. format method

Pass in a URL information object (that is, the object returned by the parse method) and return a specific path. This method is the reverse application of the parse method.

const formatUrl = url.format({
    protocol: 'https:',
    slashes: true,
    auth: null,
    host: 'www.baidu.com',
    port: null,
    hostname: 'www.baidu.com',
    hash: '#helloworld',
    search: '?name=Zhuge Liang&age=18',
    query: 'name=Zhuge Liang&age=18',
    pathname: '/news',
    path: '/news?name=Zhuge Liang&age=18',
    href: 'https://www.baidu.com/news?name=朱葛亮&age=18#helloworld'
})
console.log(formatUrl) // Output https://www.baidu.com/news?name=朱葛亮&age=18#helloworld

3. resolve method

Splicing or replacing secondary paths

const result1 = url.resolve('https://www.baidu.com', 'news')
const result2 = url.resolve('https://www.baidu.com/home', '')
const result3 = url.resolve('https://www.baidu.com/home', 'about')
const result4 = url.resolve('https://www.baidu.com/home/index', 'about')
const result5 = url.resolve('https://www.baidu.com/home/index?name=朱葛亮', 'about/hello')
console.log(result1)
console.log(result2)
console.log(result3)
console.log(result4)
console.log(result5)

Output:

Events module (event-driven)

1. Introduce the event module

2. Create an eventEmitter instance

3. Use the on method and emit method in eventEmitter to implement event-driven, similar to $on and $emit in vue, that is, publish-subscribe mode

Asynchronous requirements can be solved as follows:

import fs from 'fs'
import event from 'events'

const eventEmitter = new event.EventEmitter()

eventEmitter.on('events', data => {
    console.log('Received data', data.toString())
})

fs.readFile('static/index.html', (err, data) => {
    eventEmitter.emit('events', data)
})

The path module

import path from 'path'
// Get the suffix name const extName = path.extname('index.html') // .html

Summarize

This article ends here. I hope it can be helpful to you. I also hope that you can pay more attention to more content on 123WORDPRESS.COM!

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