How to write command tools using node. JS--Take vue-cli as an example

After the VUE-CLI is installed, the Vue command and Vue init, vue list, Vue build three subcommands are provided, and the Vue.js-based scaffolding project can be built by command. This article provides a brief description of how these commands are implemented.

Project directory for VUE-CLI

As described in the previous article, during the NPM installation process, you can use the configuration of the Bin field in Package.json to soft-connect the command file under the Bin directory to the global command. This means that four soft-connect commands are generated under/usr/local/bin: Vue, Vue-build, Vue-list, Vue-init.

The source of Vue command

#!/usr/bin/env Noderequire (' Commander ')  . Version (Require ('. /package '). Version).  usage (' <command> [Options] ').  command (' init ', ' Generate a new project from a Template ')  . Command (' list ', ' list available official templates ')  . Command (' Build ', ' prototype a new project ') C5/>.parse (PROCESS.ARGV)

　　

This command is implemented using Commander.js. The main methods of Commander are:

(1) Parse: For parsing process.argv, assigning Process.argv.slice (2) to Program.args;

(2) command: To create subcommands, subcommands are used by command <subcommand> [options], the actual call is Command-subcommand, such as using the command line to perform Vue list, is actually executing the vue-list global command;

(3) Options: The main setting of the parameters of the command, while providing a description of the parameter corresponding document, the default option is--help.

Implementation of Vue-init Sub-command

The main function of Vue-init is to pull the project template file (official or homemade) under the specified git directory into the specified directory, using the following

$ vue init <template-name> <project-name>

　　

There is still a need to parse the PROCESS.ARGV, so the commander.js is introduced in Vue-init, which generates a program

Program    . Usage (' <template-name> [Project-name] ')    . Option ('--offline ', ' Use Cached template ')/** * Help . */function Help () {    program.parse (PROCESS.ARGV)    if (Program.args.length < 1) return Program.help ()}help ()

　　

Next is to implement the pull template file, after processing, placed in the output directory, how to achieve, then there will be a special article about the implementation of the VUE-CLI command principle, please look forward to!

How to write command tools using node. JS--Take vue-cli as an example