my workflow

gulpfile.js

var gulp = require('gulp');
var sass = require('gulp-sass');
var uglify = require('gulp-uglify');
var cssnano = require('gulp-cssnano');
var imagemin = require('gulp-imagemin');
var autoprefixer = require('gulp-autoprefixer');
var htmlmin = require('gulp-htmlmin');
var browserSync = require('browser-sync').create();

gulp.task('default', ['css','javascript'], function() {		
    		browserSync.init({
        		server: "./app"					
				});
gulp.watch('app/js/*.js',["javascript"]).on('change', browserSync.reload);
gulp.watch('scss/**/*.scss',['css']);		
gulp.watch("app/*.html").on('change', browserSync.reload);
gulp.watch('./*.html',['html']);
});

gulp.task('html', function() {
  				return gulp.src('./*.html')
    				.pipe(htmlmin({collapseWhitespace: true}))
    				.pipe(gulp.dest('app'));
			});



gulp.task('imagenes', function(){
  			  gulp.src('images/*')
		        .pipe(imagemin())
		        .pipe(gulp.dest('app/images'));
});

gulp.task('javascript', function () {
			        gulp.src('app/js/*.js')
			        .pipe(uglify())
			        .pipe(gulp.dest('app/js/dist'))
});

/* FUncion sass */
gulp.task('css',function(){
	return gulp.src('scss/**/*.scss')
			.pipe(sass())
			.pipe(cssnano())	
			.pipe(autoprefixer({
		            browsers: ['last 10 versions'],
		            cascade: false
		        }))					
			.pipe(gulp.dest('app/css'))
			.pipe(browserSync.stream());			
});