Minify javascript and Css with gulp

gulpfile.js

var gulp = require('gulp');
var uglify = require('gulp-uglify');
var minifyCss = require('gulp-minify-css');


gulp.task('js', function() {
  return gulp.src('public/javascripts/*.js')
    .pipe(uglify())
    .pipe(gulp.dest('public/javascripts/min'));
});

gulp.task('css', function() {
  return gulp.src('public/stylesheets/*.css')
  	 //processImport: false if you are using @import in css
    .pipe(minifyCss({processImport: false})) 
    .pipe(gulp.dest('public/stylesheets/min'));
});

gulp.task('watch-js', function() {
    gulp.watch('public/javascripts/*.js', ['js']);
});

gulp.task('watch-css', function() {
    gulp.watch('public/stylesheets/*.css', ['css']);
});

gulp.task('default', ['js', 'watch-js','css','watch-css']);