【Node.js】Develop your own package!

Develop your own pack!

The basic structure of the initialization package

• new folder. as the root directory of the package
• In the folder, create three new files
  – package.json (package management configuration file)
  – index.js (package entry file)
  – README.md (package documentation)
• Initialize package.json

{
    
    
    "name": "lusheng-pack",//包名，包名不能和网址里的包名重复
    "version": "1.0.0",//版本号
    "main": "index.js", //包的入口文件，导入根据main，找到index.js
    "description": "功能说明",//搜索包的时候的简短描述信息
	 "keywords": ["lusheng"],//搜索关键字，必须双引号，单引号报错
    "license": "ISC"//所遵循的开源许可协议，默认ISC
}

• index.js

//包的入口文件,记录不同方法

//定义格式化时间的方法，传入日期时间
function getTime(time) {
    
    
    const dt = new Date(time)
    const y = dt.getFullYear()
    const m = padzero(dt.getMonth() + 1)
    const d = padzero(dt.getDate())
    const hh = padzero(dt.getHours())
    const mm = padzero(dt.getMinutes())
    const ss = padzero(dt.getSeconds())
    return `${
      
      y}-${
      
      m}-${
      
      d}-${
      
      hh}-${
      
      mm}-${
      
      ss}`
}
//定义补零函数
function padzero(n) {
    
    
    return n > 9 ? n : '0' + n
}
//定义转义HTML的方法,接收html
function gethtmlStr(Str) {
    
    
    return Str.replace(/<|>|"|&/g, (match) => {
    
    
        switch (match) {
    
    
            case '<':
                return '&lt;'
            case '>':
                return '&gt;'
            case '"':
                return '&quot;'
            case '&':
                return '&amp;'
        }
    })
}
//定义还原HTML的方法,接收转义语句
function sethtmlStr(Str) {
    
    
    return Str.replace(/&lt;|&gt;|&quot;|&amp;/g, (match) => {
    
    
        switch (match) {
    
    
            case '&lt;':
                return '<'
            case '&gt;':
                return '>'
            case '&quot;':
                return '"'
            case '&amp;':
                return '&'
        }
    })
}
//向外暴露的成员
module.exports = {
    
    
    getTime,
    gethtmlStr,
    sethtmlStr
}

page use

const pack = require("./index.js")
const str = `< h1 title='html语句'><span>转义啊？"&amp</span></h1>`
console.log(pack.gethtmlStr(str))
console.log(pack.sethtmlStr(pack.gethtmlStr(str)))

Modules can also be split as needed

• index.js

//包的入口文件,记录不同方法
const DateTime = require("./until/getTime.js")
const htmlStr = require("./until/getStr.js")

//向外暴露的成员,
module.exports = {
    
    
  ...DateTime,
  ...htmlStr
}

Documentation for writing packages

• User-friendly documentation for using your package
• Generally contains 6 items
• 1. Installation method
• 2. Import method
• 3. Format time
• 4. Special attention points
• 5. Open source agreement

release package

• Register npm account, website address: https://www.npmjs.com/
• Fill in account information, Full Name, Public Email, Username, Password
• Click Create an Account to register
• Log in to your email, click the verification link to verify your account
• After registration, log in to the terminal
• The npm address before each login has to be switched to the official server address, and the mirror address cannot be used.
• npm install -g nrm
• nrm use npm
• Execute the npm login command, enter the user name, password, and email address in sequence, and the login is successful.
• In the following situations, you have to go to the mailbox to get the verification code and enter it
  
• If this starts, the login is successful
  

Publish the package on npm

• Switch the terminal to the root directory and run the npm publish command to publish the package to npm (note: the package name cannot be the same)
• cd root directory name
• npm publish

remove published package

• npm unpublish package name --force, you can delete, only delete within 72 hours,
• With packages deleted in this way, republishing is not allowed within 24 hours

Module loading mechanism

• Load from cache first
• Modules are cached after the first load, which also means that require() will not cause the module's code to be executed multiple times
• Whether it is a built-in module, a user-defined module, or a third-party module, they will be loaded from the cache first, thereby improving the loading efficiency of the module

Loading mechanism for built-in modules

• Built-in modules have the highest loading priority
• For example, when importing the built-in fs module, the custom module also has fs, but the priority of importing is the fs of the built-in module

Loading mechanism for custom modules

• When loading a custom module, you must specify a path identifier starting with ./ or .../, if not specified, node will treat the custom module as a built-in module or a third-party module
• When importing a custom module, if the extension of the file is omitted, node.js will try to load the following files in order
• 1. Load according to the exact file name
• 2. Complete the .js extension loading
• 3. Complete the .json extension loading
• 4. Complete the .node extension for loading
• Failed to load, error

Loading mechanism for third-party modules

• When it is neither a built-in module nor a custom module, node.js will start from the parent directory of the current module and try to find the /node_modules folder to load the third-party module. directory, look for node_modules

Loading mechanism when a directory is a module

• 1. Find a file called package.json in the loaded directory, and look for the main attribute as the entry for require() loading
• 2. When there is no package.json file or the main entry does not exist, node.js will load the index.js file in the directory
• 3. If all fail, an error message will be printed and the missing module will be reported