gulpfile.js

/**
 * Copyright 2017 The AMP HTML Authors. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS-IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const gulp = require('gulp');
const babel = require('gulp-babel');

const config = {
  src: 'src/**/*.js',
};

gulp.task('build', function() {
  return gulp.src(config.src)
      .pipe(babel({
          presets: ['env']
      }))
      .pipe(gulp.dest('dist'));
});

gulp.task('default', function() {
  return gulp.watch([config.src], ['build'])
});