createSelfApp.js

'use strict';
const path = require('path');

const validateProjectName = require('validate-npm-package-name');// 检测包名中的字符是不是都是合法的
const chalk = require('chalk');// 一个颜色的插件
const commander = require('commander');// 解析用户命令行输入和参数
const fs = require('fs-extra');// 系统fs模块的扩展，提供了更多便利的 API

const packageJson = require('./package.json');
const templateJson = require('./config.json');

let projectName;// 定义了一个用来存储项目名称的变量

const program = new commander.Command(packageJson.name)
  .version(packageJson.version)// 输入版本信息，使用`lt-self-cli -V`的时候就用打印版本信息
  .arguments('<project-directory>')
  .usage(`${chalk.green('<project-directory>')} [options]`)
  .action(name => {
    projectName = name;
  })
  .option('--verbose', 'print additional logs')
  .allowUnknownOption()
  .on('--help', () => {
    console.log(`    Only ${chalk.green('<project-directory>')} is required.`);
    console.log();
  })
  .parse(process.argv);

if (typeof projectName === 'undefined') {
  console.error('Please specify the project directory:');
  console.log('For example:');
  console.log(`  ${chalk.cyan(program.name())} ${chalk.green('my-react-app')}`);
  console.log();
  console.log(
    `Run ${chalk.cyan(`${program.name()} --help`)} to see all options.`
  );
  process.exit(1);
}

const hiddenProgram = new commander.Command()
  .option(
    '--internal-testing-template <path-to-template>',
    '(internal usage only, DO NOT RELY ON THIS) ' +
      'use a non-standard application template'
  )
  .parse(process.argv);

createApp(projectName, program.verbose, program.scriptsVersion, hiddenProgram.internalTestingTemplate);

function createApp(name, verbose, version, template) {
  const root = path.resolve(name);
  const appName = path.basename(root);

  checkAppName(appName);
  fs.ensureDirSync(name);// 检测临时文件是否存在
  if (!isSafeToCreateProjectIn(root)) {
    console.log(
      `The directory ${chalk.green(name)} contains files that could conflict.`
    );
    console.log('Try using a new directory name.');
    process.exit(1);
  }

  console.log(`Creating a new React app in ${chalk.green(root)}.`);
  console.log();

  fs.writeFileSync(
    path.join(root, 'package.json'),
    JSON.stringify(templateJson, null, 2)
  );
  //const originalDirectory = process.cwd();// 当前目录
  process.chdir(root);// 改变工作目录

  copyTemplate(root);
  // root--e:/test/xx appName--xx version--undefined verbose--undefined originalDirectory--e:/test/ template--undefined
  // run(root, appName, version, verbose, originalDirectory, template);
}


function copyTemplate(root) {
  // Copy the files for the user
  const templatePath = path.join(__dirname, 'template');

  if (fs.existsSync(templatePath)) {
    fs.copySync(templatePath, root);
  } else {
    console.error(
      `Could not locate supplied template: ${chalk.green(templatePath)}`
    );
  }
}


function checkAppName(appName) {
  const validationResult = validateProjectName(appName);
  if (!validationResult.validForNewPackages) {
    console.error(
      `Could not create a project called ${chalk.red(`"${appName}"`)} because of npm naming restrictions:`
    );
    printValidationResults(validationResult.errors);
    printValidationResults(validationResult.warnings);
    process.exit(1);
  }

  // TODO: there should be a single place that holds the dependencies
  const dependencies = ['react', 'react-dom'];
  const devDependencies = ['react-scripts'];
  const allDependencies = dependencies.concat(devDependencies).sort();
  if (allDependencies.indexOf(appName) >= 0) {
    console.error(
      chalk.red(
        `We cannot create a project called ${chalk.green(appName)} because a dependency with the same name exists.\n` +
          `Due to the way npm works, the following names are not allowed:\n\n`
      ) +
        chalk.cyan(allDependencies.map(depName => `  ${depName}`).join('\n')) +
        chalk.red('\n\nPlease choose a different project name.')
    );
    process.exit(1);
  }
}

// If project only contains files generated by GH, it’s safe.
// We also special case IJ-based products .idea because it integrates with CRA:
// https://github.com/facebookincubator/create-react-app/pull/368#issuecomment-243446094
function isSafeToCreateProjectIn(root) {
  const validFiles = [
    '.DS_Store',
    'Thumbs.db',
    '.git',
    '.gitignore',
    '.idea',
    'README.md',
    'LICENSE',
    'web.iml',
    '.hg',
    '.hgignore',
    '.hgcheck',
  ];
  return fs.readdirSync(root).every(file => validFiles.indexOf(file) >= 0);
}

function printValidationResults(results) {
  if (typeof results !== 'undefined') {
    results.forEach(error => {
      console.error(chalk.red(`  *  ${error}`));
    });
  }
}