Minimal Gulp setup with live reload (BrowserSync) + Sass + Js

gulpfile.js

'use strict';

const autoprefixer = require('gulp-autoprefixer');
const csso = require('gulp-csso');
const del = require('del');
const gulp = require('gulp');
const sass = require('gulp-sass');
const uglify = require('gulp-uglify');
const rename = require("gulp-rename");
const browserSync = require("browser-sync");

// paths
const scss_src = './src/scss/*.scss';
const scss_out = './dist/css';
const js_src = './src/js/*.js';
const js_out = './dist/js';


// Set the supported browsers
const AUTOPREFIXER_BROWSERS = [
    'ie >= 10',
    'ie_mob >= 10',
    'ff >= 30',
    'chrome >= 34',
    'safari >= 7',
    'opera >= 23',
    'ios >= 7',
    'android >= 4.4',
    'bb >= 10'
];

// Task to minify CSS files
gulp.task('styles', function () {
    return gulp.src(scss_src)
    // Compile SASS files
    .pipe(sass({
        outputStyle: 'nested',
        precision: 10,
        includePaths: ['.'],
        onError: console.error.bind(console, 'Sass error:')
    }))
    // Auto-prefix css styles for cross browser compatibility
    .pipe(autoprefixer({Browserslist: AUTOPREFIXER_BROWSERS}))
    // Minify the file
    .pipe(csso())
    // Output
    .pipe(rename({ suffix: '.min' }))
    .pipe(gulp.dest(scss_out))
    .pipe(browserSync.stream());
});

// Task to minify JavaScript files
gulp.task('scripts', function() {
    return gulp.src(js_src)
    // Minify the file
    .pipe(uglify())
    // Output
    .pipe(rename({ suffix: '.min' }))
    .pipe(gulp.dest(js_out))
    .pipe(browserSync.stream());
});

// Clean output directory
gulp.task('clean', () => del(['dist']));

// Gulp task to minify all files
gulp.task('default', gulp.series(['clean','styles','scripts'],function () {
    // live server
    browserSync.init({
        server : './'
    });
    gulp.watch('src/**/*.scss', gulp.series('styles'));
    gulp.watch('src/**/*.js', gulp.series('scripts'));
    gulp.watch('./*.html').on('change', browserSync.reload);
}));