JS (ECMAScript 5.1) + CSS + Sass

gulpfile_js+css+sass.js

// Gulp plugins
var gulp = require('gulp'),
    minifyCSS = require('gulp-csso'),
    merge = require('merge-stream'),
    sass = require('gulp-sass'),
    concat = require('gulp-concat'),
    sourcemaps = require('gulp-sourcemaps'),
    uglify = require('gulp-uglify'),
    stripDebug = require('gulp-strip-debug');

// env variables
var build_folder = 'public/wp-content/themes/ravapanel/',
    css_paths = [
        'assets/css/*/*.css',
        'assets/css/*.css'
    ],
    sass_paths = [
        'assets/sass/**/*.sass'
    ],
    js_paths = [
        'assets/js/script.js',
        'assets/js/*/*.js',
        'assets/js/*.js'
    ];

// Styles

gulp.task('styles-dev', function () {

    var sassStream = gulp.src(sass_paths)
        .pipe(sass())
        .pipe(concat('scss-files.scss'))
    ;

    var cssStream = gulp.src(css_paths)
        .pipe(concat('css-files.css'))
    ;

    return merge(sassStream, cssStream)
        .pipe(sourcemaps.init())
        .pipe(minifyCSS())
        .pipe(concat('style.min.css'))
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest(build_folder + '/css/'));
});

gulp.task('styles-prod', function () {

    var sassStream = gulp.src(sass_paths)
        .pipe(sass())
        .pipe(concat('scss-files.scss'))
    ;

    var cssStream = gulp.src(css_paths)
        .pipe(concat('css-files.css'))
    ;

    return merge(sassStream, cssStream)
        .pipe(minifyCSS())
        .pipe(concat('style.min.css'))
        .pipe(gulp.dest(build_folder + '/css/'));
});

// JS
gulp.task('js-dev', function () {
    return gulp.src(js_paths)
        .pipe(sourcemaps.init())
        .pipe(concat('script.min.js'))
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest(build_folder + '/js'))
});

gulp.task("js-prod", function () {
    return gulp.src(js_paths)
        .pipe(concat('script.min.js'))
        .pipe(stripDebug())
        .pipe(gulp.dest(build_folder + '/js'))
});

gulp.task('js-compress', function () {
    gulp.src(build_folder + '/js/script.min.js')
        .pipe(uglify())
        .pipe(gulp.dest(build_folder + '/js'));
});

// Watchers
gulp.task('js:watch', function () {
    gulp.watch(js_paths, ['js-dev']);
});
gulp.task('styles:watch', function () {
    gulp.watch(css_paths, ['styles-dev']);
});