gulp-browsersync

gulpfile.js

var gulp = require('gulp');
var sass = require('gulp-sass');
var prefix = require('gulp-autoprefixer');
var browserSync = require('browser-sync');

gulp.task('sass', function () {
	gulp.src('scss/index.scss')
	.pipe(sass({includePaths: ['scss'], style: 'compact'}))
	.pipe(prefix("last 2 versions", "> 1%", "ie 8", "Android 2", "Firefox ESR"))
	.pipe(gulp.dest('css'));
});

gulp.task('browser-sync', function() {
	browserSync.init(["css/*.css", "js/*.js", "./*.html"], {
		server: {
			baseDir: "./"
		},
	});
});

gulp.task('default', ['sass', 'browser-sync'], function () {
	gulp.watch("scss/*.scss", ['sass']);
});