vue导入外部js文件中的函数报错，is not a constructor

Question

一个测试页面，需要导入一个外部的HTML&js日历插件，一开始出现babel问题，解决完又出现了这个问题，调试了一天实在没辙求大佬们帮忙看看。
【报的错误】（错误描述：HelloWorld.vue?b82f:15 Uncaught TypeError: __WEBPACK_IMPORTED_MODULE_1__js_simple_calendar_js__.a is not a constructor）

报错的是这一行

【test.vue】

<template>
  <div class="hello">
    <h1>{{ msg }}</h1>
    <h2>ssss</h2>

    <div id="cal"></div>

  </div>
</template>

<script>

import '../css/simple-calendar.css'
import  SimpleCalendar from '../js/simple-calendar.js'
var myCalendar = new SimpleCalendar('#cal');

export default {
  name: 'HelloWorld',
  data () {
    return {
      msg: 'Welcome to Your Vue.js App'
    }
  },mounted:function(){

  }
}
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
</style>

【插件部分HTML代码 simple-calendar.js】

export default SimpleCalendar;
var SimpleCalendar = function () {
  //构造函数

  function SimpleCalendar(query, options) {
    _classCallCheck(this, SimpleCalendar);

    //默认配置
    this._defaultOptions = {
      width: '500px',
      height: '500px',
      language: 'CH', //语言
      showLunarCalendar: true, //阴历
      showHoliday: true, //休假
      showFestival: true, //节日
      showLunarFestival: true, //农历节日
      showSolarTerm: true, //节气
      showMark: true, //标记
      onSelect: function onSelect() {},
      timeRange: {
        startYear: 1900,
        endYear: 2049
      },
      timeZone: "", //时区
      mark: {
        '2016-5-5': '上学'
      },
      theme: {
        changeAble: false,
        weeks: {
          backgroundColor: '#FBEC9C',
          fontColor: '#4A4A4A',
          fontSize: '20px'
        },
        days: {
          backgroundColor: '#ffffff',
          fontColor: '#565555',
          fontSize: '24px'
        },
        todaycolor: 'orange',
        activeSelectColor: 'orange',
        invalidDays: '#C1C0C0'
      }
    };

    //容器
    this.container = document.querySelector(query);

    this._defaultOptions.width = this.container.style.offsetWidth;
    this._defaultOptions.height = this.container.style.offsetHeight;

    //this._options = Object.assign({}, this._defaultOptions, options);

    //得到最终配置
    this._options = this.optionAssign(this._defaultOptions, options);

    this.create();
    .....
    }
  }

Answer 1

export default SimpleCalendar;
放在最后一行