Let's talk about the path, os and url modules in Node.js

This article will give you a brief understanding of the path module (path), system module (os) and url module in Node. I hope it will be helpful to you!

Node.jsThe path module provides some APIs for path operations, and the os module provides Some APIs related to the operating system are provided. The url core module provides us with APIs for parsing URL addresses. Today we mainly learn about the common APIs of the path module, os module and url module!

1. Path module (path)

Provides operation path information API

• path.extname (Get Extension of path information)

// 引入 path 模块
let path = require('path');

// 获取路径信息的扩展名
let info = path.extname('hello.html')
console.log(info);

• ##path.resolve (

  Sequence of path or path fragments Resolved as an absolute path)

//resolve把一个路径或路径片段的序列解析为一个绝对路径
let arr = ['/aaa','bbb','ccc']
let info1 = path.resolve(...arr)  //数组解构一下
console.log(info1);

##path.join (
• Use platform-specific delimiters to connect path fragments and normalize the generated path

  )

  // join使用平台特点分隔符将path片段连接，并规范化生成的路径
  console.log(__dirname);
  let info2 = path.join(__dirname,'aaa','bbb','ccc')
  console.log(info2);

Here is a brief explanation of what these mean. ：

__dirname
• : Get the complete directory name of the directory where the current executable file is located;
__filename
• : Get the complete directory name of the current executable file The file name of the absolute path;
process.cwd()
• : Get the file directory name when the node command is currently executed;

More APIs Please check the official document of node: http://nodejs.cn/api/path.html

2. System module (os)

provides some operating system related Information api

os.cpus() (
• Get cpu information

  )

os.arch( ) (
• Get system architecture: x32 or x64

  )

os.totalmem() (
• Get memory information

  )

......

For more APIs, please check the node official documentation: http://nodejs.cn/api/os.html

3. url module

The url module provides practical tools for URL processing and parsing. Two sets of APIs are provided to process URLs: one is the legacy API url.parse, url.format(), url.resolve() from the old version, and the other is the new API that implements the WHATWG standard. It is recommended to use the new version and import the module using destructuring assignment.

• Old version

  // 旧版
  // 引入 url 模块
  let url = require('url');
  // 解析(url.parse)
  let urlMore = url.parse('http://www.baidu.com?id=1&token=qwerty')  //旧版写法
  console.log(urlMore);
  
  // 合成(url.resolve)
  let urlMore2 = url.resolve('http://www.baidu.com','./aaa/ccc')
  console.log(urlMore2);

• New version

  // 新版
  // 引入 url 模块
  let {URL} = require("url");
  
  // 传入一个完整的绝对地址
  let urlMore3 = new URL('http://www.baidu.com?id=1&token=qwerty')  //新版写法
  console.log(urlMore3);
  
  // 第一个参数传入相对路径，第二个参数传入绝对路径，两者拼接进行分析
  let urlMore4 = new URL('./ads/ddd','http://www.baidu.com?')  
  console.log(urlMore4);

##Parameter analysis:

hash
• : Gets and sets the fragment part of the URL. Invalid URL characters contained in the value assigned to the hash attribute are percent-encoded.

#host
• : Get and set the host part of the URL. (That is, the domain name plus the port part).

url.hostname
• : Gets and sets the hostname part of the URL. The difference between

  url.host and url.hostname is that url.hostname does not contain the port.

href:
• Get and set the serialized URL. Getting the value of the

  href attribute is equivalent to calling url.toString(). Setting the value of this property to a new value is equivalent to using new URL(value) to create a new URL object. Every property of the URL object will be modified. If the value set to the href attribute is an invalid URL, TypeError will be thrown.

origin
• : Contains the host of the protocol, and obtains the origin of the read-only serialized URL.

#port
• : Port gets and sets the port part of the URL. The port value can be a number or a numeric string ranging from 0 to 65535 (inclusive). The port can be an empty string, in which case the port will be automatically selected according to the protocol.

protocol
• : Set the connection protocol, invalid protocol values ​​will be ignored. Such as http or https.

#search
• : Gets and sets the serialized query part of the URL.

searchParams
• : Get the

  URLSearchParams object representing the URL query parameters. This property is read-only. Use the url.search setting to replace the entire query parameters of a URL.

For more APIs, please check the node official documentation: http://nodejs.cn/api/url.html#urlresolvefrom-to

For more node-related knowledge, please visit: nodejs tutorial! !

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