create-js-app-scripts/build/plugins/watchConfiguration.js

Configuration and scripts for Create JS App

'use strict';

const chokidar = require('chokidar');
const path = require('path');

function createUpdater(env, logger) {
  return filePath => {
    // eslint-disable-line no-unused-vars
    logger.clear();
    logger.info('Detected change in configuration file, restarting environment...');
    // restart environment (terminates all plugins and loads them again)
    env.restart();
  };
}

/**
 * Watches configuration file and restarts build on change
 *
 * @param {Object} env
 * @param {boolean} runOnce   run only once (used in build script)
 * @param {Logger} logger
 */
const plugin = (env, runOnce = false, logger) => {
  let logGroup;
  let watcher;

  return {
    async build() {
      return Promise.resolve();
    },

    async start() {
      return new Promise((resolve, reject) => {
        logGroup = logger.createGroup('watch configuration');
        const updater = createUpdater(env, logGroup);

        logGroup.clear();

        // start chokidar and watch for .app.js changes
        // everytime configuration changes, restart whole build
        watcher = chokidar.watch(`${path.resolve(env.cwd, './.app.js')}`, {
          cwd: env.cwd
        });

        watcher.on('ready', () => {
          ['add', 'change', 'unlink'].forEach(event => watcher.on(event, updater));
          resolve();
        });

        watcher.on('error', error => {
          logGroup.clear();
          logGroup.error('Watch configuration plugin failed');
          logGroup.error(error);

          reject(error);
        });
      });
    },

    async terminate() {
      logGroup.remove();
      watcher.close();
    }
  };
};

module.exports = plugin;