Gulpfile.js

var gulp = require('gulp');

var autoprefixer = require('gulp-autoprefixer');
var browserSync = require('browser-sync').create();
var clean = require('gulp-clean');
var cleanCSS = require('gulp-clean-css');
var header = require('gulp-header');
var pump = require('pump');
var rename = require("gulp-rename");
var sass = require('gulp-sass');
var sourcemaps = require('gulp-sourcemaps');
var uglify = require('gulp-uglify');

var input = ['./src/**/*.scss'];
var output = './dist';

var pkg = require('./package.json');
var banner = ['/*!',
    ' * <%= pkg.name %> v<%= pkg.version %>',
    ' * @author : Irfan Maulana',
    ' * https://github.com/mazipan/bem-kit',
    ' */',
    ''
].join('\n');

var autoprefixerOptions = {
    browsers: ['last 2 versions', '> 5%', 'Firefox ESR']
};

var sassOptions = {
    outputStyle: 'compact'
};

gulp.task('clean', function() {
    return gulp.src([output], { read: false })
        .pipe(clean({ force: true }));
});

gulp.task('serve', ['simple-sass'], function() {

    browserSync.init({
        port: 3000,
        server: "./demo"
    });

    gulp.watch(input, ['simple-sass']);
    gulp.watch("./demo/*.html").on('change', browserSync.reload);
});

gulp.task('simple-sass', function() {
    return gulp
        .src(input)
        .pipe(sass(sassOptions).on('error', sass.logError))
        .pipe(autoprefixer(autoprefixerOptions))
        .pipe(gulp.dest('./demo/dist'))
        .pipe(browserSync.stream());
});

gulp.task('sass', ['clean'], function() {
    return gulp
        .src(input)
        .pipe(sass(sassOptions))
        .pipe(autoprefixer(autoprefixerOptions))
        .pipe(header(banner, { pkg: pkg }))
        .pipe(gulp.dest(output));
});

gulp.task('uglify-js', ['clean'], function(cb) {

    var uglifyOptions = {
        mangle: true,
        preserveComments: 'license'
    };

    pump([
        gulp.src('./src/*.js'),
        uglify(),
        gulp.dest(output)
    ], cb);

});

gulp.task('rename', ['sass', 'uglify-js'], function() {
    return gulp.src(["./dist/*.css", "./dist/*.js"])
        .pipe(rename(function(path) {
            path.basename += ".min";
        }))
        .pipe(gulp.dest(output));
});

gulp.task('minify-css', ['rename'], function() {
    return gulp.src('./dist/*.min.css')
        .pipe(cleanCSS({ compatibility: 'ie8' }))
        .pipe(gulp.dest(output));
});


gulp.task('build:prod', ['clean', 'sass', 'uglify-js', 'rename', 'minify-css']);
gulp.task('build:dev', ['clean', 'sass', 'serve']);
gulp.task('default', ['build:dev']);