var src = ['src/**', 'sw/**'];
var deployDir = 'docs';

var gulp = require('gulp');
var clean = require('gulp-clean');

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

gulp.task('copy', ['clean'], function() {
    return gulp.src(src)
        .pipe(gulp.dest(deployDir));
});

gulp.task('clean', function() {
    return gulp.src(deployDir)
        .pipe(clean());
});

var src = ['src/**', 'sw/**'];
var deployDir = 'docs';

var gulp = require('gulp');
var clean = require('gulp-clean');

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

gulp.task('copy', ['clean'], function() {
    return gulp.src(src)
        .pipe(gulp.dest(deployDir));
});

gulp.task('clean', function() {
    return gulp.src(deployDir)
        .pipe(clean());
});

gulp.task('serve', function() {
    var browserSync = require('browser-sync');
    browserSync({
        server: {
            baseDir: "./src/"
        },
        notify: false
    });
    gulp.watch(["./src/*"], browserSync.reload);
});

Add "gulp serve" task