使用 Node.js 构建交互式命令行工具
Node.js

> 
> 使用 Node.js 构建一个根据询问创建文件的命令行工具。
> 
> 
> 


![](/data/attachment/album/201901/02/232550x51um1yim1msd19m.jpg)


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](https://nodejs.org/en/) 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。


### 开始


首先，创建一个新的 [npm](https://www.npmjs.com/) 包（NPM 是 JavaScript 包管理器）。



```
mkdir my-script
cd my-script
npm init
```

NPM 将会问一些问题。随后，我们需要安装一些包。



```
npm install --save chalk figlet inquirer shelljs
```

这是我们需要的包：


* Chalk：正确设定终端的字符样式
* 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）
* Inquirer：通用交互式命令行用户界面的集合
* ShellJS：Node.js 版本的可移植 Unix Shell 命令行工具


### 创建一个 index.js 文件


现在我们要使用下述内容创建一个 `index.js` 文件。



```
#!/usr/bin/env node

const inquirer = require("inquirer");
const chalk = require("chalk");
const figlet = require("figlet");
const shell = require("shelljs");
```

### 规划命令行工具


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**。


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。



```
// index.js

const run = async () => {
  // show script introduction
  // ask questions
  // create the file
  // show success message
};

run();
```

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。



```
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();
```

然后，我们来写一个函数来问问题。



```
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
};
```

注意，常量 `FILENAME` 和 `EXTENSIONS` 来自 `inquirer` 包。


下一步将会创建文件。



```
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
};
```

最后，重要的是，我们将展示成功信息以及文件路径。



```
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);
};
```

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：


![](/data/attachment/album/201901/02/232558i5attqw939zgbdrk.png)


### 完整代码


下述代码为完整代码：



```
#!/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();
```

### 使用这个脚本


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`：



```
{
  "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"
  }
}
```

执行 `npm link` 使得这个脚本可以在任何地方调用。


这就是是当你运行这个命令时的结果。



```
/usr/bin/creator -> /usr/lib/node_modules/creator/index.js
/usr/lib/node_modules/creator -> /home/hugo/code/creator
```

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`。


现在我们可以通过执行如下命令来调用。



```
$ creator
```

### 总结


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。


* [meow](https://github.com/sindresorhus/meow)：一个简单的命令行助手工具
* [yargs](https://github.com/yargs/yargs)：一个命令行参数解析工具
* [pkg](https://github.com/zeit/pkg)：将你的 Node.js 程序包装在一个可执行文件中。


在评论中留下你关于构建命令行工具的经验吧！




---


via: <https://opensource.com/article/18/7/node-js-interactive-cli>


作者：[Hugo Dias](https://opensource.com/users/hugodias) 选题：[lujun9972](https://github.com/lujun9972) 译者：[bestony](https://github.com/bestony) 校对：[wxy](https://github.com/wxy)


本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出


OK
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](https://nodejs.org/en/) to build a CLI that asks some questions and creates a file based on the answers.

![NodeJS CLI output NodeJS CLI output](https://opensource.com/sites/default/files/uploads/nodejs_output.png)

## Get started

Let's start by creating a brand new [npm](https://www.npmjs.com/) 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:

![NodeJS CLI output NodeJS CLI output](https://opensource.com/sites/default/files/uploads/nodejs_output.png)

## 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](https://github.com/sindresorhus/meow)– a simple command-line helper[yargs](https://github.com/yargs/yargs)– a command-line opt-string parser[pkg](https://github.com/zeit/pkg)– package your Node.js project into an executable

Tell us about your experience building a CLI in the comments.

## Comments are closed.