My Go To Gulp File

gulpfile.js

var gulp = require('gulp');
var watch = require('gulp-watch');
var cleanCSS = require('gulp-clean-css');
var uglify = require('gulp-uglify');
var rename = require('gulp-rename');
var concat = require('gulp-concat');
var merge = require('merge-stream');
var scss = require('gulp-scss');

function version(){
  var now = new Date(),
    Y = now.getFullYear(),
    m = now.getMonth()+1,
    d = now.getDate(),
    H = now.getHours(),
    i = now.getMinutes(),
    s = now.getSeconds();

    if(H < 10) {
        H = '0' + H;
    }

    if(i < 10) {
        i = '0' + i;
    }

    if(s < 10) {
        s = '0' + s;
    }

    return String(10000*Y + 100*m + d + '.' + H + i + s);
}

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

gulp.task('build-css', function(){
  var full = gulp.src([
    'public/src/scss/main.scss'
  ])
  . pipe(scss())
  . pipe(concat('default.css'))
  . pipe(gulp.dest('public/dist/css'));

  var min = gulp.src([
    'public/src/scss/main.scss'
  ])
  . pipe(scss())
  . pipe(cleanCSS())
  . pipe(concat('default.min.' + version() + '.css'))
  . pipe(gulp.dest('public/dist/css'));

  return merge(full, min);
});

gulp.task('build-js', function() {
  var full = gulp.src([
    'public/src/js/main.js'
  ])
  .pipe(concat('default.js'))
  .pipe(gulp.dest('public/dist/js'));

  var min = gulp.src([
    'public/src/js/main.js'
  ])
  .pipe(concat('default.min.' +  version()  + '.js'))
  .pipe(uglify())
  .pipe(gulp.dest('public/dist/js'));

  return merge(full, min);
});

gulp.task('watch', function(){
  gulp.watch('./public/src/scss/**/*.scss', ['build-css']);
  gulp.watch('./public/src/js/**/*.js', ['build-js']);
});

package.json

"devDependencies": {
  "gulp": "^3.9.1",
  "gulp-clean-css": "^3.9.2",
  "gulp-concat": "^2.6.1",
  "gulp-rename": "^1.2.2",
  "gulp-scss": "^1.4.0",
  "gulp-uglify": "^3.0.0",
  "gulp-watch": "^5.0.0",
  "merge-stream": "^1.0.1"
}