gulpfile.babel.js

const gulp = require('gulp')
const concat = require('gulp-concat')
const uglify = require('gulp-uglify')
const babel = require('gulp-babel')
const header = require('gulp-header')
const pkg = require('./package.json')

const banner = [
  '/*! ',
  '<%= package.name %> ',
  'v<%= package.version %> | ',
  '(c) ' + new Date().getFullYear() + ' <%= package.author %> |',
  ' <%= package.homepage %>',
  ' */',
  '\n'
].join('');

gulp.task('js', () => {
  return gulp.src('src/*.js')
    .pipe(babel({
      presets: ['@babel/env']
    }))
    .pipe(concat('poster.js'))
    .pipe(header(banner, {
      package: pkg
    }))
    .pipe(gulp.dest('dist/'))
    .pipe(uglify())
    .pipe(concat('poster.min.js'))
    .pipe(header(banner, {
      package: pkg
    }))
    .pipe(gulp.dest('dist/'))
});

gulp.watch('src/**/*.js', function(e) {
  gulp.start('js')
})

gulp.task('default', ['js'])