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336 lines
7.6 KiB
Markdown
336 lines
7.6 KiB
Markdown
使用 Node.js 构建交互式命令行工具
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======
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> 使用 Node.js 构建一个根据询问创建文件的命令行工具。
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当用于构建命令行界面（CLI）时，Node.js 十分有用。在这篇文章中，我将会教你如何使用 [Node.js][1] 来构建一个问一些问题并基于回答创建一个文件的命令行工具。
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### 开始
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首先，创建一个新的 [npm][2] 包（NPM 是 JavaScript 包管理器）。
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```
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mkdir my-script
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cd my-script
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npm init
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```
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NPM 将会问一些问题。随后，我们需要安装一些包。
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```
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npm install --save chalk figlet inquirer shelljs
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```
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这是我们需要的包：
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* Chalk：正确设定终端的字符样式
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* Figlet：使用普通字符制作大字母的程序（LCTT 译注：使用标准字符，拼凑出图片）
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* Inquirer：通用交互式命令行用户界面的集合
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* ShellJS：Node.js 版本的可移植 Unix Shell 命令行工具
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### 创建一个 index.js 文件
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现在我们要使用下述内容创建一个 `index.js` 文件。
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```
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#!/usr/bin/env node
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const inquirer = require("inquirer");
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const chalk = require("chalk");
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const figlet = require("figlet");
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const shell = require("shelljs");
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```
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### 规划命令行工具
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在我们写命令行工具所需的任何代码之前，做计划总是很棒的。这个命令行工具只做一件事：**创建一个文件**。
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它将会问两个问题：文件名是什么以及文件后缀名是什么？然后创建文件，并展示一个包含了所创建文件路径的成功信息。
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```
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// index.js
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const run = async () => {
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// show script introduction
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// ask questions
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// create the file
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// show success message
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};
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run();
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```
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第一个函数只是该脚本的介绍。让我们使用 `chalk` 和 `figlet` 来把它完成。
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```
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const init = () => {
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console.log(
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chalk.green(
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figlet.textSync("Node JS CLI", {
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font: "Ghost",
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horizontalLayout: "default",
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verticalLayout: "default"
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})
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)
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);
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}
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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// create the file
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// show success message
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};
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run();
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```
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然后，我们来写一个函数来问问题。
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```
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const askQuestions = () => {
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const questions = [
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{
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name: "FILENAME",
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type: "input",
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message: "What is the name of the file without extension?"
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},
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{
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type: "list",
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name: "EXTENSION",
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message: "What is the file extension?",
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choices: [".rb", ".js", ".php", ".css"],
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filter: function(val) {
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return val.split(".")[1];
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}
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}
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];
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return inquirer.prompt(questions);
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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// show success message
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};
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```
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注意，常量 `FILENAME` 和 `EXTENSIONS` 来自 `inquirer` 包。
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下一步将会创建文件。
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```
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const createFile = (filename, extension) => {
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const filePath = `${process.cwd()}/${filename}.${extension}`
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shell.touch(filePath);
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return filePath;
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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};
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```
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最后，重要的是，我们将展示成功信息以及文件路径。
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```
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const success = (filepath) => {
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console.log(
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chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
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);
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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success(filePath);
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};
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```
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来让我们通过运行 `node index.js` 来测试这个脚本，这是我们得到的：
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### 完整代码
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下述代码为完整代码：
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```
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#!/usr/bin/env node
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const inquirer = require("inquirer");
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const chalk = require("chalk");
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const figlet = require("figlet");
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const shell = require("shelljs");
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const init = () => {
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console.log(
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chalk.green(
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figlet.textSync("Node JS CLI", {
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font: "Ghost",
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horizontalLayout: "default",
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verticalLayout: "default"
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})
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)
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);
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};
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const askQuestions = () => {
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const questions = [
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{
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name: "FILENAME",
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type: "input",
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message: "What is the name of the file without extension?"
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},
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{
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type: "list",
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name: "EXTENSION",
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message: "What is the file extension?",
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choices: [".rb", ".js", ".php", ".css"],
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filter: function(val) {
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return val.split(".")[1];
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}
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}
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];
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return inquirer.prompt(questions);
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};
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const createFile = (filename, extension) => {
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const filePath = `${process.cwd()}/${filename}.${extension}`
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shell.touch(filePath);
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return filePath;
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};
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const success = filepath => {
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console.log(
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chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
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);
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};
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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success(filePath);
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};
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run();
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```
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### 使用这个脚本
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想要在其它地方执行这个脚本，在你的 `package.json` 文件中添加一个 `bin` 部分，并执行 `npm link`：
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```
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{
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"name": "creator",
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"version": "1.0.0",
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"description": "",
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"main": "index.js",
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"scripts": {
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"test": "echo \"Error: no test specified\" && exit 1",
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"start": "node index.js"
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},
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"author": "",
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"license": "ISC",
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"dependencies": {
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"chalk": "^2.4.1",
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"figlet": "^1.2.0",
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"inquirer": "^6.0.0",
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"shelljs": "^0.8.2"
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},
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"bin": {
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"creator": "./index.js"
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}
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}
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```
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执行 `npm link` 使得这个脚本可以在任何地方调用。
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这就是是当你运行这个命令时的结果。
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```
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/usr/bin/creator -> /usr/lib/node_modules/creator/index.js
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/usr/lib/node_modules/creator -> /home/hugo/code/creator
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```
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这会连接 `index.js` 作为一个可执行文件。这是完全可能的，因为这个 CLI 脚本的第一行是 `#!/usr/bin/env node`。
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现在我们可以通过执行如下命令来调用。
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```
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$ creator
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```
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### 总结
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正如你所看到的，Node.js 使得构建一个好的命令行工具变得非常简单。如果你希望了解更多内容，查看下列包。
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* [meow][3]：一个简单的命令行助手工具
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* [yargs][4]：一个命令行参数解析工具
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* [pkg][5]：将你的 Node.js 程序包装在一个可执行文件中。
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在评论中留下你关于构建命令行工具的经验吧！
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/7/node-js-interactive-cli
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作者：[Hugo Dias][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[bestony](https://github.com/bestony)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://opensource.com/users/hugodias
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[1]:https://nodejs.org/en/
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[2]:https://www.npmjs.com/
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[3]:https://github.com/sindresorhus/meow
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[4]:https://github.com/yargs/yargs
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[5]:https://github.com/zeit/pkg
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