Gulp 4 + nodemon + livereload for AngularJS and legacy monolithic apps

gulpfile.js

'use strict'
require('custom-env').env(); //Load .env file
const { src, dest, watch } = require('gulp');
const sass = require('gulp-sass')(require('sass'));
const autoprefixer = require('gulp-autoprefixer');
const uglify = require('gulp-uglify-es').default;
const browserify = require('browserify');
const source = require('vinyl-source-stream');
const buffer = require('vinyl-buffer');
const nodemon = require('gulp-nodemon');
const livereload = require('gulp-livereload');
const notify = require('gulp-notify');

const compileSass = () => {
	return src('./app/app.scss')
	.pipe(autoprefixer())
	.pipe(
		sass({
			'outputStyle': 'compressed'
		})
	.on('error', sass.logError))
	.pipe(dest('./app/build'))
	.pipe(livereload())
	.pipe(notify('CSS Reloaded'));
};
const watchSass = () => {
	return watch([
		'./app/Components/**/**/*.scss',
		'./app/Directives/**/*.scss',
		'./app/app.scss'
   ], compileSass);   
};
const compileJs = async () => {
	let b = browserify({
		entries: './app/app.js',
	});
	return b.bundle()
	.pipe(source('app.js'))
	.pipe(buffer())
	.pipe(uglify({
		ecma: 5,
		keep_fnames: true,
		keep_classnames: true,
		mangle: false
	}).on('error', function (e) {
		console.log(e)
	}))
	.pipe(dest('./app/build'))
	.pipe(livereload())
	.pipe(notify('JS Reloaded'));
};
const watchJs = async () => {
   return watch([
		'./app/Components/**/**/*.js',
		'./app/Directives/**/*.js',
		'./app/Services/*.js',
		'./app/app.js'
   ], compileJs);
}
const compileHtml = (file) => {
	return src(file)
	.pipe(livereload())
	.pipe(notify('HTML Reloaded'));
}
const watchHtml	= async () => {
	return watch('./app/Components/**/**/*.html').on('change', (file) => {
		compileHtml(file);
	});
}

const nodemonServer = async (cb) => {
	livereload.listen();
	nodemon({
		script: 'server.js',
		env: {'NODE_ENV': 'dev'},
		ignore: [
			'/app/',
			'/app/build/',
			'/app/Components/',
			'/app/Directives/',
			'/app/Services/',
		]
	}).on('start', () => {
		
	})
	.on('restart', (files) => {
		livereload.changed(files);
	});
	await Promise.resolve(cb);
}

const start = async () => {
	watchHtml();
	watchSass();
	watchJs();
	nodemonServer();
}

exports.compileSass = compileSass;
exports.compileJs = compileJs;
exports.watchSass = watchSass;
exports.watchJs = watchJs;
exports.start = start;