gulp setup must be improved

gulpfile.js

var
gulp         = require('gulp'),
stylus       = require('gulp-stylus'),
postcss      = require('gulp-postcss'),
sourcemaps   = require('gulp-sourcemaps'),
autoprefixer = require('autoprefixer'),
rupture      = require('rupture'),
nunjucksRender = require('gulp-nunjucks-render'),
lost         = require('lost'),
plumber      = require('gulp-plumber'),
gutil        = require('gulp-util'),
data         = require('./jsonplaceholder');

var onError = function (err) {
  gutil.beep();
  gutil.log('stylus fehler', gutil.color.magenta('123'));
  console.log(err);
};

gulp.task('styles', function() {
    return gulp
        .src('./src/stylus/*')
        .pipe(plumber({
            errorHandler: onError
        }))
        .pipe(sourcemaps.init())
        .pipe(stylus({
            use: rupture(),
            compress: false,
            linenos: true,
            }))
        .pipe(
            postcss([
                lost(),
                autoprefixer()
            ])
        )
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest('./build/css'));
});

gulp.task('templates', function() {
    return gulp
        .src('./src/views/*.*')
        .pipe(nunjucksRender(data))
        .pipe(gulp.dest('./build/'));
});

gulp.task('js',function(){
    return gulp
        .src('./src/js/**/*.js')
        .pipe(gulp.dest('./build/js/'))
})



gulp.watch('./src/js/*.*',['js']);
gulp.watch('./src/views/*.html',['templates']);
gulp.watch('./src/stylus/**/*.styl', ['styles']);


gulp.task('default',['styles', 'js', 'templates']);