Nodejs basic architecture analysis parsing engine directory plug-in installation core module

   Development nodejs Relevant procedures , Need to be right nodejs Have a comprehensive overview , First learn how many existing libraries there are , How is it structured , How to install plug-ins, etc , So when facing the project task , Only in this way can we have the bottom of our hearts .

1.nodejs summary

  Node.js It's based on Chrome V8 Engine JavaScript Running environment . V8 The engine performs Javascript Very fast , Very good performance .Node.js An event driver is used 、 Non-blocking type I/O Of JavaScript Model . because web Security considerations for the operating environment , Running in browser JavaScript There are many limitations , In order to make it usable in a wider environment ,nodejs This part of the function is supplemented . This paper mainly introduces its application in front-end interface development , Generally based on Google Chromium Development . The engine name is CEPHtmlEngine, The directory of the parsing engine is shown in the following figure ：

2. Basic framework

   As shown in the figure above ：your code For user code ,node.js The core ,Host environment For the host environment （ Provide all kinds of services , Such as document management , Multithreading , Multi process ,IO etc）

  nodejs Part of the ：v8 engine, libuv, builtin modules, native modules And other ancillary services .
  v8 engine： There are two main functions 1. Functions of virtual machine , perform js Code （ Own code , Third party code and native modules Code for ）.2. Provide C++ The function interface , by nodejs Provide v8 initialization , establish context,scope etc. .
  libuv： It's event driven asynchronous IO model base , our js Code issue request , In the end by the libuv complete , The callback function we set is in libuv Trigger .
  builtin modules： It is from C++ Code written into various modules , Contains crypto,zlib, file stream etc Basic function .（v8 Function interface is provided ,libuv Provide asynchrony IO model base , As well as some nodejs function , by builtin modules Provide services ）.
  native modules： It is from js It's written in , Provide the library that our application calls , At the same time, these modules depend on builtin modules To get the corresponding service support .
   summary ： If you put nodejs As a black box , What is exposed to developers is native modules, When we make a request , Request from top to bottom , through native modules, adopt builtin modules Send the request to v8,libuv And other ancillary services , End of request , Then go back from the bottom to the top , Finally, we call our callback function .

3.nodejs Version history

   It can be found on the official website , Download required nodejs Installation environment ,https://nodejs.org/en/download/releases/

4.windows Next nodejs Directory structure

   download node-v8.17.0-x64 edition , stay windows7 Lower installation , After completion, the directory structure is shown in the figure below ：

   Open the console and navigate to the directory , You can use npm Command to install other plug-ins . Set the npm After the plug-in installation path , Will automatically create one under the path you set node_modules Folder to store plug-ins .

5.nodejs Plug-in management (npm) The basic function of the module

   install npm modular .
   view help ：npm help/npm h
   Install the module ：npm install <module name>/ npm install -g <Module Name>
   Unloading module ：ninstall <Moudle Name>
   Displays the modules installed in the current directory ：npm list