woocommerce/plugins/woocommerce-admin/bin/packages/watch.js

/**
 * External dependencies
 */
const fs = require( 'fs' );
const { execSync } = require( 'child_process' );
const path = require( 'path' );
const chalk = require( 'chalk' );
const watch = require( 'node-watch' );

/**
 * Internal dependencies
 */
const getPackages = require( './get-packages' );

const BUILD_CMD = `node ${ path
	.resolve( __dirname, './build.js' )
	.replace( /(\s+)/g, '\\$1' ) }`;

let filesToBuild = new Map();

const exists = ( filename ) => {
	try {
		return fs.statSync( filename ).isFile();
	} catch ( e ) {}
	return false;
};

// Exclude deceitful source-like files, such as editor swap files.
const isSourceFile = ( filename ) => {
	return /.\.(js|ts|tsx|scss)$/.test( filename );
};

const rebuild = ( filename ) => filesToBuild.set( filename, true );

getPackages().forEach( ( p ) => {
	const srcDir = path.resolve( p, 'src' );
	try {
		fs.accessSync( srcDir, fs.F_OK );
		watch(
			path.resolve( p, 'src' ),
			{ recursive: true },
			( event, filename ) => {
				const filePath = path.resolve( srcDir, filename );

				if ( ! isSourceFile( filename ) ) {
					return;
				}

				if (
					[ 'update', 'change', 'rename' ].includes( event ) &&
					exists( filePath )
				) {
					// eslint-disable-next-line no-console
					console.log(
						chalk.green( '->' ),
						`${ event }: ${ filename }`
					);
					rebuild( filePath );
				} else {
					const buildFile = path.resolve(
						srcDir,
						'..',
						'build',
						filename
					);
					try {
						fs.unlinkSync( buildFile );
						process.stdout.write(
							chalk.red( '  \u2022 ' ) +
								path.relative(
									path.resolve( srcDir, '..', '..' ),
									buildFile
								) +
								' (deleted)' +
								'\n'
						);
					} catch ( e ) {}
				}
			}
		);
	} catch ( e ) {
		// doesn't exist
	}
} );

setInterval( () => {
	const files = Array.from( filesToBuild.keys() );
	if ( files.length ) {
		filesToBuild = new Map();
		try {
			execSync(
				`${ BUILD_CMD } ${ files
					.map( ( file ) => file.replace( /(\s+)/g, '\\$1' ) )
					.join( ' ' ) }`,
				{ stdio: [ 0, 1, 2 ] }
			);
		} catch ( e ) {}
	}
}, 100 );

// eslint-disable-next-line no-console
console.log( chalk.red( '->' ), chalk.cyan( 'Watching for changes...' ) );