Gulpfile with Sourcemaps and File Minification

gulpfile.js

'use strict';

var config = {
    project: 'bta',
    stylePaths: [
      './scss/style.scss'
    ],
    jsPaths: [
      './js/*'
    ]
};

var gulp = require('gulp'),
    sass = require('gulp-sass'),
    rename = require('gulp-rename'),
    csso = require('gulp-csso'),
    concat = require('gulp-concat'),
    uglify = require('gulp-uglify'),
    sourcemaps = require('gulp-sourcemaps');

// Styles task
gulp.task('stylesheet', function () {
  gulp.src(config.stylePaths)
  .pipe(sourcemaps.init())
  .pipe(sass().on('error', sass.logError))
  .pipe(csso())
  .pipe(rename('style.css'))
  .pipe(sourcemaps.write('maps'))
  .pipe(gulp.dest('./'));
});

// Javascript  task
gulp.task('javascript', function() {
  gulp.src(config.jsPaths)
  .pipe(sourcemaps.init())
  // Bundle to a single file
  .pipe(concat('bundle.js'))
  .pipe(uglify())
  .pipe(sourcemaps.write('maps'))
  .pipe(gulp.dest('./dist/'));
});

// Watch tasks
gulp.task('watch', function() {
  // styles
  gulp.watch(['./scss/**/*.scss'], [
      'stylesheet'
  ]);
  
  gulp.watch(config.jsPaths, [
    'javascript'
  ]);
});

// build task
gulp.task('build', ['stylesheet', 'javascript']);

// default task
gulp.task('default', ['build', 'watch']);

package.json

  "devDependencies": {
    "csso": "^2.2.1",
    "node-sass": "^4.11.0"
  },
  "dependencies": {
    "gulp": "^3.9.1",
    "gulp-concat": "*",
    "gulp-csso": "^2.0.0",
    "gulp-rename": "*",
    "gulp-sass": "^4.0.2",
    "gulp-sourcemaps": "^2.6.5",
    "gulp-uglify": "*"
  }