gulpfile.js

const gulp = require('gulp');
const browsersync = require("browser-sync").create();
const uglify = require('gulp-uglify');
const sourcemaps = require('gulp-sourcemaps');
const browserify = require('browserify');
const babelify = require('babelify');
const source = require('vinyl-source-stream');
const buffer = require('vinyl-buffer');

var paths = {
	dev: {
		html: 'demo/typopo-demo.html',
		index: 'typopo-demo.html',
		name: 'typopo_browser.built.js',
		dest: 'build/'
	},
	browser: {
		src: 'src/browser_typopo.js',
		name: 'typopo.min.js',
		dest: 'dist/'
	},
	npm: {
		src: 'src/typopo.js',
		name: 'typopo_dist.min.js',
		dest: 'dist/'
	}
};

/*
 * Define our tasks using plain functions
 */

function devBrowserBuild() {
	return browserify({entries: paths.browser.src, debug: true})
		.transform("babelify")
		.bundle()
		.pipe(source(paths.dev.name))
		.pipe(buffer())
		.pipe(sourcemaps.init())
		.pipe(sourcemaps.write('./maps'))
		.pipe(gulp.dest(paths.dev.dest))
 }


function browserBuild() {
	return browserify({ entries: paths.browser.src, debug: false })
	.transform(babelify)
	.bundle()
	.pipe(source(paths.browser.name))
	.pipe(buffer())
	.pipe(uglify())
	.pipe(gulp.dest(paths.browser.dest));
}

function npmBuild() {
	return browserify({entries: paths.npm.src}, {standalone: 'typopo'})
		.transform("babelify")
		.bundle()
		.pipe(source(paths.npm.name))
		.pipe(buffer())
		.pipe(uglify())
		.pipe(gulp.dest(paths.npm.dest))
}

function copyHtmlToDest() {
	return gulp
		.src(paths.dev.html)
		.pipe(gulp.dest(paths.dev.dest));
}

function watchFiles() {
	gulp.watch(
		[
			paths.npm.src,
			paths.browser.src,
			paths.dev.html,
			"./src/**/*",
		],
			gulp.series(devBrowserBuild, copyHtmlToDest, browserSyncReload)
		);
}

// BrowserSync
function browserSync(done) {
	browsersync.init({
		server: {
			baseDir: 'build/',
			index: 'typopo-demo.html'
		},
		port: 3000
	});
	done();
}

// BrowserSync Reload
function browserSyncReload(done) {
	browsersync.reload();
	done();
}

const watch = gulp.parallel(watchFiles, browserSync);
const build = gulp.parallel(npmBuild, browserBuild);

exports.watch = watch;
exports.build = build;
/*
 * Define default task that can be called by just running `gulp` from cli
 */
exports.default = build;