browserSync

gulpfile.js

var gulp = require('gulp');
var browserSync = require('browser-sync').create();
var sass = require('gulp-sass');

gulp.task('browser-sync', ['sass'], function() {
	browserSync.init({
	    server: "app",
			port: 8080,
	});
	gulp.watch('app/scss/**/*.scss', ['sass']);
	gulp.watch("app/*.html").on('change', browserSync.reload);
});

gulp.task('sass', function() {
  return gulp.src('app/scss/styles.scss')
	.pipe(sass())
  .pipe(gulp.dest('app/css'))
	.pipe(browserSync.stream());
});