【中高级前端必备】手摸手教你撸一个脚手架
脚手架
vue-cli, create-react-app、react-native-cli 等都是非常优秀的脚手架，通过脚手架，我们可以快速初始化一个项目，无需自己从零开始一步步配置，有效提升开发体验。尽管这些脚手架非常优秀，但是未必是符合我们的实际应用的，我们可以定制一个属于自己的脚手架(或公司通用脚手架)，来提升自己的开发效率。
脚手架的作用
实现的功能
在开始之前，我们需要明确自己的脚手架需要哪些功能。vue init template-name project-name 、create-react-app project-name。我们这次编写的脚手架(eos-cli)具备以下能力(脚手架的名字爱叫啥叫啥，我选用了Eos黎明女神):
大家可以自行扩展其它的 commander，本篇文章旨在教大家如何实现一个脚手架。
效果展示
初始化一个项目
修改.eosrc文件，从 vuejs-template 下载模板
需要使用的第三方库
关于这些第三方库的说明，可以直接npm上查看相应的说明，此处不一一展开。
初始化项目
创建一个空项目(eos-cli)，使用 npm init 进行初始化。
安装依赖
npm install babel-cli babel-env chalk commander download-git-repo ini inquirer log-symbols ora目录结构
├── bin│ └── www //可执行文件├── dist ├── ... //生成文件└── src ├── config.js //管理eos配置文件 ├── index.js //主流程入口文件 ├── init.js //init command ├── main.js //入口文件 └── utils ├── constants.js //定义常量 ├── get.js //获取模板 └── rc.js //配置文件├── .babelrc //babel配置文件├── package.json├── README.md//可执行文件
├── dist
├── ... //生成文件
└── src
├── config.js //管理eos配置文件
├── index.js //主流程入口文件
├── init.js //init command
├── main.js //入口文件
└── utils
├── constants.js //定义常量
├── get.js //获取模板
└── rc.js //配置文件
├── .babelrc //babel配置文件
├── package.json
├── README.md
babel 配置
开发使用了ES6语法，使用 babel 进行转义，
.bablerc
{ "presets": [ [ "env", { "targets": { "node": "current" } } ] ]}"presets": [
[
"env",
{
"targets": {
"node": "current"
}
}
]
]
}
`eos` 命令
node.js 内置了对命令行操作的支持，package.json 中的 bin 字段可以定义命令名和关联的执行文件。在 package.json 中添加 bin 字段
package.json
{ "name": "eos-cli", "version": "1.0.0", "description": "脚手架", "main": "index.js", "bin": { "eos": "./bin/www" }, "scripts": { "compile": "babel src -d dist", "watch": "npm run compile -- --watch" }}"name": "eos-cli",
"version": "1.0.0",
"description": "脚手架",
"main": "index.js",
"bin": {
"eos": "./bin/www"
},
"scripts": {
"compile": "babel src -d dist",
"watch": "npm run compile -- --watch"
}
}
www 文件
行首加入一行 #!/usr/bin/env node 指定当前脚本由node.js进行解析
#! /usr/bin/env noderequire('../dist/main.js');
require('../dist/main.js');
链接到全局环境
开发过程中为了方便调试，在当前的 eos-cli 目录下执行 npm link，将 eos 命令链接到全局环境。
启动项目
npm run watch处理命令行
利用 commander 来处理命令行。
main
import program from 'commander';import { VERSION } from './utils/constants';import apply from './index';import chalk from 'chalk';/** * eos commands * - config * - init */let actionMap = { init: { description: 'generate a new project from a template', usages: [ 'eos init templateName projectName' ] }, config: { alias: 'cfg', description: 'config .eosrc', usages: [ 'eos config set ', 'eos config get ', 'eos config remove ' ] }, //other commands}// 添加 init / config 命令Object.keys(actionMap).forEach((action) => { program.command(action) .description(actionMap[action].description) .alias(actionMap[action].alias) //别名 .action(() => { switch (action) { case 'config': //配置 apply(action, ...process.argv.slice(3)); break; case 'init': apply(action, ...process.argv.slice(3)); break; default: break; } });});function help() { console.log('\r\nUsage:'); Object.keys(actionMap).forEach((action) => { actionMap[action].usages.forEach(usage => { console.log(' - ' + usage); }); }); console.log('\r');}program.usage(' [options]');// eos -h program.on('-h', help);program.on('--help', help);// eos -V VERSION 为 package.json 中的版本号program.version(VERSION, '-V --version').parse(process.argv);// eos 不带参数时if (!process.argv.slice(2).length) { program.outputHelp(make_green);}function make_green(txt) { return chalk.green(txt); }from 'commander';
import { VERSION } from './utils/constants';
import apply from './index';
import chalk from 'chalk';
/**
* eos commands
* - config
* - init
*/
let actionMap = {
init: {
description: 'generate a new project from a template',
usages: [
'eos init templateName projectName'
]
},
config: {
alias: 'cfg',
description: 'config .eosrc',
usages: [
'eos config set ' ,
'eos config get ' ,
'eos config remove '
]
},
//other commands
}
// 添加 init / config 命令
Object.keys(actionMap).forEach((action) => {
program.command(action)
.description(actionMap[action].description)
.alias(actionMap[action].alias) //别名
.action(() => {
switch (action) {
case 'config':
//配置
apply(action, ...process.argv.slice(3));
break;
case 'init':
apply(action, ...process.argv.slice(3));
break;
default:
break;
}
});
});
function help() {
console.log('\r\nUsage:');
Object.keys(actionMap).forEach((action) => {
actionMap[action].usages.forEach(usage => {
console.log(' - ' + usage);
});
});
console.log('\r');
}
program.usage(' [options]' );
// eos -h
program.on('-h', help);
program.on('--help', help);
// eos -V VERSION 为 package.json 中的版本号
program.version(VERSION, '-V --version').parse(process.argv);
// eos 不带参数时
if (!process.argv.slice(2).length) {
program.outputHelp(make_green);
}
function make_green(txt) {
return chalk.green(txt);
}
下载模板
download-git-repo 支持从 Github、Gitlab 下载远程仓库到本地。
get.js
import { getAll } from './rc';import downloadGit from 'download-git-repo';export const downloadLocal = async (templateName, projectName) => { let config = await getAll(); let api = `${config.registry}/${templateName}`; return new Promise((resolve, reject) => { //projectName 为下载到的本地目录 downloadGit(api, projectName, (err) => { if (err) { reject(err); } resolve(); }); });}from './rc';
import downloadGit from 'download-git-repo';
export const downloadLocal = async (templateName, projectName) => {
let config = await getAll();
let api = `${config.registry}/${templateName}`;
return new Promise((resolve, reject) => {
//projectName 为下载到的本地目录
downloadGit(api, projectName, (err) => {
if (err) {
reject(err);
}
resolve();
});
});
}
`init` 命令
命令行交互
在用户执行 init 命令后，向用户提出问题，接收用户的输入并作出相应的处理。命令行交互利用 inquirer 来实现:
inquirer.prompt([ { name: 'description', message: 'Please enter the project description: ' }, { name: 'author', message: 'Please enter the author name: ' }]).then((answer) => { //...});
name: 'description',
message: 'Please enter the project description: '
},
{
name: 'author',
message: 'Please enter the author name: '
}
]).then((answer) => {
//...
});
视觉美化
在用户输入之后，开始下载模板，这时候使用 ora 来提示用户正在下载模板，下载结束之后，也给出提示。
import ora from 'ora';let loading = ora('downloading template ...');loading.start();//downloadloading.succeed(); //或 loading.fail();from 'ora';
let loading = ora('downloading template ...');
loading.start();
//download
loading.succeed(); //或 loading.fail();
index.js
import { downloadLocal } from './utils/get';import ora from 'ora';import inquirer from 'inquirer';import fs from 'fs';import chalk from 'chalk';import symbol from 'log-symbols';let init = async (templateName, projectName) => { //项目不存在 if (!fs.existsSync(projectName)) { //命令行交互 inquirer.prompt([ { name: 'description', message: 'Please enter the project description: ' }, { name: 'author', message: 'Please enter the author name: ' } ]).then(async (answer) => { //下载模板 选择模板 //通过配置文件，获取模板信息 let loading = ora('downloading template ...'); loading.start(); downloadLocal(templateName, projectName).then(() => { loading.succeed(); const fileName = `${projectName}/package.json`; if(fs.existsSync(fileName)){ const data = fs.readFileSync(fileName).toString(); let json = JSON.parse(data); json.name = projectName; json.author = answer.author; json.description = answer.description; //修改项目文件夹中 package.json 文件 fs.writeFileSync(fileName, JSON.stringify(json, null, '\t'), 'utf-8'); console.log(symbol.success, chalk.green('Project initialization finished!')); } }, () => { loading.fail(); }); }); }else { //项目已经存在 console.log(symbol.error, chalk.red('The project already exists')); }}module.exports = init;from './utils/get';
import ora from 'ora';
import inquirer from 'inquirer';
import fs from 'fs';
import chalk from 'chalk';
import symbol from 'log-symbols';
let init = async (templateName, projectName) => {
//项目不存在
if (!fs.existsSync(projectName)) {
//命令行交互
inquirer.prompt([
{
name: 'description',
message: 'Please enter the project description: '
},
{
name: 'author',
message: 'Please enter the author name: '
}
]).then(async (answer) => {
//下载模板 选择模板
//通过配置文件，获取模板信息
let loading = ora('downloading template ...');
loading.start();
downloadLocal(templateName, projectName).then(() => {
loading.succeed();
const fileName = `${projectName}/package.json`;
if(fs.existsSync(fileName)){
const data = fs.readFileSync(fileName).toString();
let json = JSON.parse(data);
json.name = projectName;
json.author = answer.author;
json.description = answer.description;
//修改项目文件夹中 package.json 文件
fs.writeFileSync(fileName, JSON.stringify(json, null, '\t'), 'utf-8');
console.log(symbol.success, chalk.green('Project initialization finished!'));
}
}, () => {
loading.fail();
});
});
}else {
//项目已经存在
console.log(symbol.error, chalk.red('The project already exists'));
}
}
module.exports = init;
`config` 配置
eos config set registry vuejs-templatesconfig 配置，支持我们使用其它仓库的模板，例如，我们可以使用 vuejs-templates 中的仓库作为模板。这样有一个好处：更新模板无需重新发布脚手架，使用者无需重新安装，并且可以自由选择下载目标。
config.js
// 管理 .eosrc 文件 (当前用户目录下)import { get, set, getAll, remove } from './utils/rc';let config = async (action, key, value) => { switch (action) { case 'get': if (key) { let result = await get(key); console.log(result); } else { let obj = await getAll(); Object.keys(obj).forEach(key => { console.log(`${key}=${obj[key]}`); }) } break; case 'set': set(key, value); break; case 'remove': remove(key); break; default: break; }}module.exports = config;
import { get, set, getAll, remove } from './utils/rc';
let config = async (action, key, value) => {
switch (action) {
case 'get':
if (key) {
let result = await get(key);
console.log(result);
} else {
let obj = await getAll();
Object.keys(obj).forEach(key => {
console.log(`${key}=${obj[key]}`);
})
}
break;
case 'set':
set(key, value);
break;
case 'remove':
remove(key);
break;
default:
break;
}
}
module.exports = config;
rc.js
.eosrc 文件的增删改查
import { RC, DEFAULTS } from './constants';import { decode, encode } from 'ini';import { promisify } from 'util';import chalk from 'chalk';import fs from 'fs';const exits = promisify(fs.exists);const readFile = promisify(fs.readFile);const writeFile = promisify(fs.writeFile);//RC 是配置文件//DEFAULTS 是默认的配置export const get = async (key) => { const exit = await exits(RC); let opts; if (exit) { opts = await readFile(RC, 'utf8'); opts = decode(opts); return opts[key]; } return '';}export const getAll = async () => { const exit = await exits(RC); let opts; if (exit) { opts = await readFile(RC, 'utf8'); opts = decode(opts); return opts; } return {};}export const set = async (key, value) => { const exit = await exits(RC); let opts; if (exit) { opts = await readFile(RC, 'utf8'); opts = decode(opts); if(!key) { console.log(chalk.red(chalk.bold('Error:')), chalk.red('key is required')); return; } if(!value) { console.log(chalk.red(chalk.bold('Error:')), chalk.red('value is required')); return; } Object.assign(opts, { [key]: value }); } else { opts = Object.assign(DEFAULTS, { [key]: value }); } await writeFile(RC, encode(opts), 'utf8');}export const remove = async (key) => { const exit = await exits(RC); let opts; if (exit) { opts = await readFile(RC, 'utf8'); opts = decode(opts); delete opts[key]; await writeFile(RC, encode(opts), 'utf8'); }}from './constants';
import { decode, encode } from 'ini';
import { promisify } from 'util';
import chalk from 'chalk';
import fs from 'fs';
const exits = promisify(fs.exists);
const readFile = promisify(fs.readFile);
const writeFile = promisify(fs.writeFile);
//RC 是配置文件
//DEFAULTS 是默认的配置
export const get = async (key) => {
const exit = await exits(RC);
let opts;
if (exit) {
opts = await readFile(RC, 'utf8');
opts = decode(opts);
return opts[key];
}
return '';
}
export const getAll = async () => {
const exit = await exits(RC);
let opts;
if (exit) {
opts = await readFile(RC, 'utf8');
opts = decode(opts);
return opts;
}
return {};
}
export const set = async (key, value) => {
const exit = await exits(RC);
let opts;
if (exit) {
opts = await readFile(RC, 'utf8');
opts = decode(opts);
if(!key) {
console.log(chalk.red(chalk.bold('Error:')), chalk.red('key is required'));
return;
}
if(!value) {
console.log(chalk.red(chalk.bold('Error:')), chalk.red('value is required'));
return;
}
Object.assign(opts, { [key]: value });
} else {
opts = Object.assign(DEFAULTS, { [key]: value });
}
await writeFile(RC, encode(opts), 'utf8');
}
export const remove = async (key) => {
const exit = await exits(RC);
let opts;
if (exit) {
opts = await readFile(RC, 'utf8');
opts = decode(opts);
delete opts[key];
await writeFile(RC, encode(opts), 'utf8');
}
}
发布
npm publish 将本脚手架发布至npm上。其它用户可以通过 npm install eos-cli -g 全局安装。
即可使用 eos 命令。
项目地址
本项目完整代码请戳: https://github.com/YvetteLau/Blog/tree/master/eos-cli