我试图将ES6模块导入到一个文件中，并运行Gulp来连接和缩小该文件。我遇到了ReferenceError：js（transpiled）第3行。我已经用gulp-babel把代码翻译了。
我的js文件是：

购物车.js：

class Cart{
  constructor(){
    this.cart = [];
    this.items = items = [{
        id: 1,
        name: 'Dove Soap',
        price: 39.99
    },{
        id: 2,
        name: 'Axe Deo',
        price: 99.99
    }];
  }

  getItems(){
    return this.items;
  }

}

export {Cart};

应用程序.js：

import {Cart} from 'cart.js';

let cart = new Cart();

console.log(cart.getItems());

gulpfile.js文件类型：

"use strict";

let gulp = require('gulp');
let jshint = require('gulp-jshint');
let concat = require('gulp-concat');
let uglify = require('gulp-uglify');
let rename = require('gulp-rename');
let babel = require('gulp-babel');

// Lint Task
gulp.task('lint', function() {
    return gulp.src('js/*.js')
        .pipe(jshint())
        .pipe(jshint.reporter('default'));
});

// Concatenate & Minify JS
gulp.task('scripts', function() {
    return gulp.src('js/*.js')
        .pipe(babel({
            presets: ['env']
        }))
        .pipe(concat('all.js'))
        .pipe(gulp.dest('dist'))
        .pipe(rename('all.min.js'))
        .pipe(uglify().on('error', function(e){
          console.dir(e);
        }))
        .pipe(gulp.dest('dist/js'));
});

// Default Task
gulp.task('default', ['lint','scripts']);

应用程序.js（已转换）：

'use strict';

var _cart = require('cart.js'); //Uncaught ReferenceError: require is not defined

var cart = new _cart.Cart();

console.log(cart.getItems());
'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Cart = function () {
  function Cart() {
    _classCallCheck(this, Cart);

    this.cart = [];
    this.items = items = [{
      id: 1,
      name: 'Dove Soap',
      price: 39.99
    }, {
      id: 2,
      name: 'Axe Deo',
      price: 99.99
    }];
  }

  _createClass(Cart, [{
    key: 'getItems',
    value: function getItems() {
      return this.items;
    }
  }]);

  return Cart;
}();

exports.Cart = Cart;