Master Node.js CLI Development with Commander, Inquirer, and Chalk

Prerequisites and Project Setup

Start a new project, run npm init to generate package.json, create a main entry file without an extension, and install the required modules: npm install commander inquirer chalk --save-dev The devDependencies section of package.json will now contain these packages:

{
  "name": "app",
  "version": "1.0.0",
  "description": "玩转命令行开发",
  "main": "index.js",
  "scripts": { "test": "echo \"Error: no test specified\" && exit 1" },
  "author": "ykg",
  "license": "ISC",
  "devDependencies": {
    "chalk": "^1.1.3",
    "commander": "^2.9.0",
    "inquirer": "^1.1.2"
  }
}

Commander Overview

Commander, inspired by Ruby's option parser, simplifies command‑line argument parsing and sub‑command handling. Its main features include parameter parsing, polymorphic commands, variadic arguments, Git‑style sub‑commands, automatic help generation, and customizable help text.

Parameter parsing

Polymorphic commands

Variadic arguments

Git‑style sub‑commands

Automatic help information

Customizable help

Simple Example

const program = require('commander');
const inquirer = require('inquirer');
const chalk = require('chalk');

program
  .command('module')
  .alias('m')
  .description('创建新的模块')
  .option('-a, --name [moduleName]', '模块名称')
  .action(option => {
    console.log('Hello World'); // 示例输出
  });

program.parse(process.argv);

Run the script with node app.js module (or the alias m) to see the "Hello World" output.

Running as a Global Command

To make the CLI tool globally executable:

Add a bin field to package.json: "bin": { "app": "app" } Execute npm link to create a symbolic link in the global node_modules directory and add the command to PATH.

Place a shebang line at the top of the entry file: #!/usr/bin/env node After these steps, the command can be run globally with app module or app m.

Commander API Details

command – defines a sub‑command, e.g., .command('app [name]').

alias – creates a short alias, e.g., $ app m.

description – text shown in the help output.

option – declares an option; supports short and long flags, description, optional callback, and default value.

action – registers the callback executed when the command runs (note: let is not supported in the callback).

parse – parses the command‑line arguments.

Generating Help Information

Automatic help is available via --help: $ app m --help Custom help can be added by listening to the --help event:

program.on('--help', function() {
  console.log('  Examples:');
  console.log('');
  console.log('$ app module moduleName');
  console.log('$ app m moduleName');
});

Inquirer for Interactive Prompts

Inquirer provides a simple way to ask questions in the terminal. Basic usage:

var inquirer = require('inquirer');
inquirer.prompt([/* questions */]).then(function(answers) {
  // handle answers
});

Older code may use a traditional callback style:

inquirer.prompt([/* questions */], function(answers) {
  // handle answers
});

Inquirer Features

input – free‑form text entry

validate – input validation

list – selectable list

confirm – yes/no prompt

checkbox – multiple selection

A more complete example combines commander, inquirer, and lodash to collect module name, description, and optional CSS pre‑processor choice:

const program = require('commander');
const inquirer = require('inquirer');
const _ = require('lodash');
const chalk = require('chalk');

program
  .command('module')
  .alias('m')
  .description('创建新的模块')
  .option('--name [moduleName]')
  .option('--sass', '启用sass')
  .option('--less', '启用less')
  .action(option => {
    const config = _.assign({
      moduleName: null,
      description: '',
      sass: false,
      less: false
    }, option);
    const prompts = [];
    if (typeof config.moduleName !== 'string') {
      prompts.push({
        type: 'input',
        name: 'moduleName',
        message: '请输入模块名称',
        validate: input => input ? true : '不能为空'
      });
    }
    if (typeof config.description !== 'string') {
      prompts.push({
        type: 'input',
        name: 'moduleDescription',
        message: '请输入模块描述'
      });
    }
    if (!config.sass && !config.less) {
      prompts.push({
        type: 'list',
        name: 'cssPretreatment',
        message: '想用什么css预处理器呢',
        choices: [
          { name: 'Sass/Compass', value: 'sass' },
          { name: 'Less', value: 'less' }
        ]
      });
    }
    inquirer.prompt(prompts).then(answers => {
      console.log(chalk.green('收工咯'));
      console.log(chalk.blue('收工咯'));
      console.log(chalk.blue.bgRed('收工咯'));
      console.log(chalk.blue(answers));
    });
  })
  .on('--help', function() {
    console.log('  Examples:');
    console.log('');
    console.log('$ app module moduleName');
    console.log('$ app m moduleName');
  })
  .parse(process.argv);

Chalk for Colored Output

Chalk adds color and style to terminal strings with a lightweight API:

const chalk = require('chalk');
console.log(chalk.red('开启前端工程化之路'));
console.log(chalk.green('收工咯'));
console.log(chalk.blue.bgRed('收工咯'));

References

Athena (frontend workflow tool): https://github.com/o2team/athena

Commander npm package: https://www.npmjs.com/package/commander

Inquirer npm package: https://www.npmjs.com/package/inquirer

Chalk npm package: https://www.npmjs.com/package/chalk

Example source code: https://github.com/yangzicheng/command-line