gulpfile.js

var gulp = require('gulp');
var autoprefixer = require('gulp-autoprefixer');
var babelify = require('babelify');
var browserify = require('browserify');
var concat = require('gulp-concat');
var eslint = require('gulp-eslint');
var less = require('gulp-less');
var minifyCSS = require('gulp-minify-css');
var source = require("vinyl-source-stream");
var uglify = require('gulp-uglify');
var watch = require('gulp-watch');

gulp.task('less', function () {
  return gulp.src('client/less/**/*.less')
    .pipe(less())
    .pipe(concat('style.css'))
    .pipe(minifyCSS())
    .pipe(autoprefixer({
      browsers: ['last 2 versions']
    }))
    .pipe(gulp.dest('www/css'));
});

gulp.task('browserify', function () {
  return browserify({
      entries: './client/js/main.js'
    })
    .transform(babelify)
    .bundle()
    .pipe(source("main.js"))
    .pipe(gulp.dest('www/js'));
});

gulp.task('js', ['browserify'], function () {
  return gulp.src(['client/js/sw.js'])
    .pipe(uglify())
    .pipe(gulp.dest('www'));
});

gulp.task('lint', function () {
  return gulp.src(['server/**/*.js'])
    .pipe(eslint())
    .pipe(eslint.format())
    .pipe(eslint.failOnError());
});

gulp.task('build', ['less', 'js']);

gulp.task('watch', function () {
  watch('client/less/**/*.less', function () {
    gulp.start('less');
  });
  watch('client/js/**/*.js', function () {
    gulp.start('js');
  });
});