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From: darksun <lujun9972@gmail.com>
Date: Mon, 30 Jul 2018 13:10:25 +0800
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+Build an interactive CLI with Node.js
+======
+
+![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming_keyboard_coding.png?itok=E0Vvam7A)
+
+Node.js can be very useful when it comes to building command-line interfaces (CLIs). In this post, I'll teach you how to use [Node.js][1] to build a CLI that asks some questions and creates a file based on the answers.
+
+### Get started
+
+Let's start by creating a brand new [npm][2] package. (Npm is the JavaScript package manager.)
+```
+mkdir my-script
+
+cd my-script
+
+npm init
+
+```
+
+Npm will ask some questions. After that, we need to install some packages.
+```
+npm install --save chalk figlet inquirer shelljs
+
+```
+
+Here's what these packages do:
+
+  * **Chalk:** Terminal string styling done right
+  * **Figlet:** A program for making large letters out of ordinary text
+  * **Inquirer:** A collection of common interactive command-line user interfaces
+  * **ShellJS:** Portable Unix shell commands for Node.js
+
+
+
+### Make an index.js file
+
+Now we'll create an `index.js` file with the following content:
+```
+#!/usr/bin/env node
+
+
+
+const inquirer = require("inquirer");
+
+const chalk = require("chalk");
+
+const figlet = require("figlet");
+
+const shell = require("shelljs");
+
+```
+
+### Plan the CLI
+
+It's always good to plan what a CLI needs to do before writing any code. This CLI will do just one thing: **create a file**.
+
+The CLI will ask two questions—what is the filename and what is the extension?—then create the file, and show a success message with the created file path.
+```
+// index.js
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  // ask questions
+
+  // create the file
+
+  // show success message
+
+};
+
+
+
+run();
+
+```
+
+The first function is the script introduction. Let's use `chalk` and `figlet` to get the job done.
+```
+const init = () => {
+
+  console.log(
+
+    chalk.green(
+
+      figlet.textSync("Node JS CLI", {
+
+        font: "Ghost",
+
+        horizontalLayout: "default",
+
+        verticalLayout: "default"
+
+      })
+
+    )
+
+  );
+
+}
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  init();
+
+
+
+  // ask questions
+
+  // create the file
+
+  // show success message
+
+};
+
+
+
+run();
+
+```
+
+Second, we'll write a function that asks the questions.
+```
+const askQuestions = () => {
+
+  const questions = [
+
+    {
+
+      name: "FILENAME",
+
+      type: "input",
+
+      message: "What is the name of the file without extension?"
+
+    },
+
+    {
+
+      type: "list",
+
+      name: "EXTENSION",
+
+      message: "What is the file extension?",
+
+      choices: [".rb", ".js", ".php", ".css"],
+
+      filter: function(val) {
+
+        return val.split(".")[1];
+
+      }
+
+    }
+
+  ];
+
+  return inquirer.prompt(questions);
+
+};
+
+
+
+// ...
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  init();
+
+
+
+  // ask questions
+
+  const answers = await askQuestions();
+
+  const { FILENAME, EXTENSION } = answers;
+
+
+
+  // create the file
+
+  // show success message
+
+};
+
+```
+
+Notice the constants FILENAME and EXTENSIONS that came from `inquirer`.
+
+The next step will create the file.
+```
+const createFile = (filename, extension) => {
+
+  const filePath = `${process.cwd()}/${filename}.${extension}`
+
+  shell.touch(filePath);
+
+  return filePath;
+
+};
+
+
+
+// ...
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  init();
+
+
+
+  // ask questions
+
+  const answers = await askQuestions();
+
+  const { FILENAME, EXTENSION } = answers;
+
+
+
+  // create the file
+
+  const filePath = createFile(FILENAME, EXTENSION);
+
+
+
+  // show success message
+
+};
+
+```
+
+And last but not least, we'll show the success message along with the file path.
+```
+const success = (filepath) => {
+
+  console.log(
+
+    chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
+
+  );
+
+};
+
+
+
+// ...
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  init();
+
+
+
+  // ask questions
+
+  const answers = await askQuestions();
+
+  const { FILENAME, EXTENSION } = answers;
+
+
+
+  // create the file
+
+  const filePath = createFile(FILENAME, EXTENSION);
+
+
+
+  // show success message
+
+  success(filePath);
+
+};
+
+```
+
+Let's test the script by running `node index.js`. Here's what we get:
+
+### The full code
+
+Here is the final code:
+```
+#!/usr/bin/env node
+
+
+
+const inquirer = require("inquirer");
+
+const chalk = require("chalk");
+
+const figlet = require("figlet");
+
+const shell = require("shelljs");
+
+
+
+const init = () => {
+
+  console.log(
+
+    chalk.green(
+
+      figlet.textSync("Node JS CLI", {
+
+        font: "Ghost",
+
+        horizontalLayout: "default",
+
+        verticalLayout: "default"
+
+      })
+
+    )
+
+  );
+
+};
+
+
+
+const askQuestions = () => {
+
+  const questions = [
+
+    {
+
+      name: "FILENAME",
+
+      type: "input",
+
+      message: "What is the name of the file without extension?"
+
+    },
+
+    {
+
+      type: "list",
+
+      name: "EXTENSION",
+
+      message: "What is the file extension?",
+
+      choices: [".rb", ".js", ".php", ".css"],
+
+      filter: function(val) {
+
+        return val.split(".")[1];
+
+      }
+
+    }
+
+  ];
+
+  return inquirer.prompt(questions);
+
+};
+
+
+
+const createFile = (filename, extension) => {
+
+  const filePath = `${process.cwd()}/${filename}.${extension}`
+
+  shell.touch(filePath);
+
+  return filePath;
+
+};
+
+
+
+const success = filepath => {
+
+  console.log(
+
+    chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
+
+  );
+
+};
+
+
+
+const run = async () => {
+
+  // show script introduction
+
+  init();
+
+
+
+  // ask questions
+
+  const answers = await askQuestions();
+
+  const { FILENAME, EXTENSION } = answers;
+
+
+
+  // create the file
+
+  const filePath = createFile(FILENAME, EXTENSION);
+
+
+
+  // show success message
+
+  success(filePath);
+
+};
+
+
+
+run();
+
+```
+
+### Use the script anywhere
+
+To execute this script anywhere, add a `bin` section in your `package.json` file and run `npm link`.
+```
+{
+
+  "name": "creator",
+
+  "version": "1.0.0",
+
+  "description": "",
+
+  "main": "index.js",
+
+  "scripts": {
+
+    "test": "echo \"Error: no test specified\" && exit 1",
+
+    "start": "node index.js"
+
+  },
+
+  "author": "",
+
+  "license": "ISC",
+
+  "dependencies": {
+
+    "chalk": "^2.4.1",
+
+    "figlet": "^1.2.0",
+
+    "inquirer": "^6.0.0",
+
+    "shelljs": "^0.8.2"
+
+  },
+
+  "bin": {
+
+    "creator": "./index.js"
+
+  }
+
+}
+
+```
+
+Running `npm link` makes this script available anywhere.
+
+That's what happens when you run this command:
+```
+/usr/bin/creator -> /usr/lib/node_modules/creator/index.js
+
+/usr/lib/node_modules/creator -> /home/hugo/code/creator
+
+```
+
+It links the `index.js` file as an executable. This is only possible because of the first line of the CLI script: `#!/usr/bin/env node`.
+
+Now we can run this script by calling:
+```
+$ creator
+
+```
+
+### Wrapping up
+
+As you can see, Node.js makes it very easy to build nice command-line tools! If you want to go even further, check this other packages:
+
+  * [meow][3] – a simple command-line helper
+  * [yargs][4] – a command-line opt-string parser
+  * [pkg][5] – package your Node.js project into an executable
+
+
+
+Tell us about your experience building a CLI in the comments.
+
+--------------------------------------------------------------------------------
+
+via: https://opensource.com/article/18/7/node-js-interactive-cli
+
+作者：[Hugo Dias][a]
+选题：[lujun9972](https://github.com/lujun9972)
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]:https://opensource.com/users/hugodias
+[1]:https://nodejs.org/en/
+[2]:https://www.npmjs.com/
+[3]:https://github.com/sindresorhus/meow
+[4]:https://github.com/yargs/yargs
+[5]:https://github.com/zeit/pkg