Gulp dev-script

gulpfile-config.js

module.exports = {
    vendor_js: [
        // 'node_modules/path/to/vendor/**/*.js'
    ],
    vendor_css: [
        // 'node_modules/path/to/vendor/**/*.css'
    ],
    fonts: [
        // 'node_modules/**/*.{ttf,woff,woff2,eot,svg}'
    ],
    scss: [
        'app/Resources/scss/**/*.scss'
    ],
    js: [
        'app/Resources/js/**/*.js'
    ]
}

gulpfile.js

// optimized for symfony project
var path = require('path')
var gulp = require('gulp')
var concat = require('gulp-concat')
var minify = require('gulp-minify')
var replace = require('gulp-replace')
var sass = require('gulp-sass')
var cleanCss = require('gulp-clean-css')
var flatten = require('gulp-flatten')
var browserSync = require('browser-sync').create()
var proxy = 'http://fal.dev/'+path.basename(__dirname)+'/web/app_dev.php'

gulp.task('group-js', function() {
    gulp.src([
        'node_modules/jquery/dist/jquery.js',
        'node_modules/popper.js/dist/umd/popper.js',
        'node_modules/bootstrap/dist/js/bootstrap.js'
        ])
        // .pipe(minify())
        .pipe(concat('vendor.js'))
        .pipe(gulp.dest('web/assets'))
        .pipe(browserSync.stream())
})
gulp.task('group-css', function() {
    var urlPattern = /url(?:\(['"]?)(?:.*?)([\w\-\.\?=#&]+?)(?:['"]?\))/g

    gulp.src([
        // 'node_modules/**/*.{ttf,woff,woff2,eot,svg}'
        ])
        .pipe(flatten())
        .pipe(gulp.dest('web/assets/fonts'))

    gulp.src([
        // 'node_modules/path/to/vendor/**/*.css'
        ])
        .pipe(replace(urlPattern, 'url("fonts/$1")'))
        .pipe(cleanCss())
        .pipe(concat('vendor.css'))
        .pipe(gulp.dest('web/assets'))
        .pipe(browserSync.stream())
})
gulp.task('style', function() {
    gulp.src('app/Resources/scss/**/*.scss')
        .pipe(sass({outputStyle: 'compressed'}).on('error', sass.logError))
        .pipe(gulp.dest('web/assets'))
        .pipe(browserSync.stream())
})
gulp.task('script', function() {
    gulp.src('app/Resources/js/**/*.js')
        .pipe(minify())
        .pipe(gulp.dest('web/assets'))
        .pipe(browserSync.stream())
})
gulp.task('watch', ['style','script','group-js','group-css'], function() {
    browserSync.init({
        proxy: proxy,
        online: false,
        ghostMode: false,
        open: false
    })

    gulp.watch('app/Resources/scss/**/*.scss', ['style'])
    gulp.watch('app/Resources/js/**/*.js', ['script'])
    gulp.watch(['app/**/*.yml', 'app/**/*.twig', 'web/*.php', 'src/**/*']).on('change', browserSync.reload)
})
gulp.task('default', ['watch'])

install command.sh

npm install --save-dev browser-sync gulp gulp-clean-css gulp-concat gulp-flatten gulp-minify gulp-replace gulp-sass

package.json

{
  "name": "appname",
  "devDependencies": {
    "browser-sync": "^2.18.7",
    "gulp": "^3.9.1",
    "gulp-clean-css": "^3.9.0",
    "gulp-concat": "^2.6.1",
    "gulp-flatten": "^0.3.1",
    "gulp-minify": "^1.0.0",
    "gulp-replace": "^0.5.4",
    "gulp-sass": "^3.1.0"
  },
  "dependencies": {
  }
}