走读 react-app-rewired (2.1.5)

bin/index

#!/usr/bin/env node

var spawn = require('react-dev-utils/crossSpawn');

/**

 * 解析参数

 */

const args = process.argv.slice(2);

const scriptIndex = args.findIndex(

  x => x === 'build' || x === 'eject' || x === 'start' || x === 'test'

);

const script = scriptIndex === -1 ? args[0] : args[scriptIndex];

const nodeArgs = scriptIndex > 0 ? args.slice(0, scriptIndex) : [];

switch (script) {

  /**

   * 命令是build、eject、start、test 启动node线程执行对应js命令，否则退出给提示

   */

  case 'build':

  case 'eject':

  case 'start':

  case 'test': {

    const result = spawn.sync(

      'node',

      nodeArgs

        .concat(require.resolve('../scripts/' + script))

        .concat(args.slice(scriptIndex + 1)),

      { stdio: 'inherit' }

    );

    if (result.signal) {

      if (result.signal === 'SIGKILL') {

        console.log(

          'The build failed because the process exited too early. ' +

            'This probably means the system ran out of memory or someone called ' +

            '`kill -9` on the process.'

        );

      } else if (result.signal === 'SIGTERM') {

        console.log(

          'The build failed because the process exited too early. ' +

            'Someone might have called `kill` or `killall`, or the system could ' +

            'be shutting down.'

        );

      }

      process.exit(1);

    }

    process.exit(result.status);

    break;

  }

  default:

    console.log('Unknown script "' + script + '".');

    console.log('Perhaps you need to update react-scripts?');

    console.log(

      'See: https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#updating-to-new-releases'

    );

    break;

}

 

scripts/start

 

/**

 * 判断CRA版本，

 * 没有自定义文件目录时，读取项目根目录下的config-overrides

 * 从缓存里替换配置信息，然后执行react-scripts

 */

process.env.NODE_ENV = process.env.NODE_ENV || 'development';

const semver = require('semver');

const { scriptVersion } = require('./utils/paths');

const overrides = require('../config-overrides');

const scriptPkg = require(`${scriptVersion}/package.json`);

// CRA 2.1.2 switched to using a webpack config factory

// https://github.com/facebook/create-react-app/pull/5722

// https://github.com/facebook/create-react-app/releases/tag/v2.1.2

const isWebpackFactory = semver.gte(scriptPkg && scriptPkg.version, '2.1.2');

const webpackConfigPath = `${scriptVersion}/config/webpack.config${!isWebpackFactory ? '.dev' : ''}`;

const devServerConfigPath = `${scriptVersion}/config/webpackDevServer.config.js`;

const webpackConfig = require(webpackConfigPath);

const devServerConfig = require(devServerConfigPath);

// override config in memory

require.cache[require.resolve(webpackConfigPath)].exports = isWebpackFactory

  ? (env) => overrides.webpack(webpackConfig(env), env)

  : overrides.webpack(webpackConfig, process.env.NODE_ENV);

require.cache[require.resolve(devServerConfigPath)].exports =

  overrides.devServer(devServerConfig, process.env.NODE_ENV);

const pathsConfigPath = `${scriptVersion}/config/paths.js`;

const pathsConfig = require(pathsConfigPath);

// override paths in memory

require.cache[require.resolve(pathsConfigPath)].exports =

  overrides.paths(pathsConfig, process.env.NODE_ENV);

// run original script

require(`${scriptVersion}/scripts/start`);