gulpfile.js

const gulp = require('gulp');
const babel = require('gulp-babel');
const sass = require('gulp-sass');
const pug = require('gulp-pug');
const plumber = require('gulp-plumber');
const autoprefixer = require('gulp-autoprefixer');
const cleanCSS = require('gulp-clean-css');
const rename = require("gulp-rename");
const filter = require('gulp-filter');
const uglify = require('gulp-uglify');

const babelOpts = {
    presets: ['es2015'],
    compact: false
};

gulp.task('webHtml', () => {
    const pugOpts = {
        data: {},
        pretty: false,
        compileDebug: true
    };
    gulp.src('./src/html/**/*.pug').pipe(filter(file => !/\/_/.test(file.path) && !/^_/.test(file.relative))).pipe(plumber()).pipe(pug(pugOpts)).pipe(gulp.dest('./dist/'))
});

gulp.task('webCss', () => {
    const sassOpts = {
        outputStyle: 'nested'
    };

    gulp.src(`./src/css/main.scss`).pipe(sass(sassOpts).on('error', sass.logError)).pipe(autoprefixer({
        browsers: [
            'ff >= 4', 'Chrome >= 19', 'ie >= 9'
        ],
        cascade: false
    })).pipe(cleanCSS()).pipe(gulp.dest('./dist/css/'))
});

gulp.task('webJs', () => {

    gulp.src('./src/js/**/*.es6').pipe(plumber()).pipe(babel(babelOpts)).pipe(uglify()).pipe(gulp.dest('./dist/js/'))
});

gulp.task('build', ['webJs', 'webCss', 'webHtml']);

gulp.task('default', () => {
    gulp.watch('./src/css/**/*.scss', ['webCss']);

    gulp.watch('./src/html/**/*.pug', ['webHtml']);
    gulp.watch('./src/js/**/*.es6', ['webJs']);
});