未捕获的 ReferenceError：在初始化之前无法访问“__WEBPACK_DEFAULT_EXPORT__”

Question

我的 webpack 项目有问题，所以我试图将一个类导入另一个类并实例化它，但突然在我的控制台中出现一个错误，我的程序停止工作，是这样的：

Uncaught ReferenceError: Cannot access '__WEBPACK_DEFAULT_EXPORT__' before initialization

这是我试图导入另一个类（即 PopUpPlugin）时的类代码：

import PopupPlugin from './popupPlugin.js';

export const addSearchBtnEvent = (weatherUI) => {
  const searchBtn = document.querySelector('.weather__search');
  
  searchBtn.addEventListener('click', () => {
    weatherUI.style.opacity = '1';
    weatherUI.style.visibility = 'visible';
  })
}

export const addSearchExitEvent = (weatherUI) => {
  const weatherExit = document.querySelector('.weather__search-exit');
  
  weatherExit.addEventListener('click', () => {
    weatherUI.style.opacity = '0';
    weatherUI.style.visibility = 'hidden';
  })
}

const popupObj = new PopupPlugin();

class searchDashboard {
  constructor() {
    
  }
  
  setInputEvent() {
    const inputSearch = document.querySelector('.weather__city-search');
    const inputSearchBtn = document.querySelector('.weather__search-btn');
    
    inputSearchBtn.addEventListener('click', () => {
      const inputSearchVal = inputSearch.value;
      
      this.validateStr(inputSearchVal);
    });
  }
  
  validateStr() {
    const onlyLettersAndSpaces = /^[a-zA-Z][a-zA-Z\s]*$/;
    
    if(str.trim().length > 0 && str.match(onlyLettersAndSpaces)) {
      const strValue = str.toLowerCase().trim().replace(' ', '+');
      
      this.popupObj.searchCoincidences(strValue, 'weather__search-ui');
    }
  }
}

export default searchDashboard;

我实际上不知道为什么会这样，我也尝试在构造函数中实例化它并且它工作但它向我发送了堆栈溢出的错误。

PD：如果有人需要，这里是 PopupPlugin 的代码。 （这对我来说是在构造函数中实例化类，直到出现堆栈溢出错误）

import ManageWeatherDashboard from './manageWeatherDashboard.js';
import { getFetch, repeatAppend } from './weatherHelpers.js';

class popupPlugin {
  constructor() {
    this.manageWeatherDashboardObj = new ManageWeatherDashboard();
  }

  validateStr(str) {
    const onlyLettersAndSpaces = /^[a-zA-Z][a-zA-Z\s]*$/;
    
    if(str.trim().length > 0 && str.match(onlyLettersAndSpaces)) {
      const strValue = str.toLowerCase().trim().replace(' ', '+');
      
      return strValue;
    }
  }
  
  searchCoincidences(val, parent) {
    getFetch(`https://www.metaweather.com/api/location/search/?query=${val}`)
      .then(res => res.text())
      .then(data => {
        const parentResults = document.querySelector('.'+parent);
        
        parentResults.innerHTML = '';
        
        const dataArr = JSON.parse(data)
        
        if(dataArr.length >= 15) {
          let resVal;
          
          for(let i = 0; i <= 15; i++) {
            resVal = this.addDOMResultCoincidences(parent, dataArr[i].title,
              dataArr[i].woeid);
          }
          
          this.whenClickCoincidence(resVal);
        } else {
          let resVal;
          
          dataArr.forEach(el => {
            resVal = this.addDOMResultCoincidences(parent, el.title, el.woeid);
          })
          
          this.whenClickCoincidence(resVal);
        }
        
      })
  }
  
  addDOMResultCoincidences(parentBlock, name, id) {
    const args = Array.from(arguments);
    
    if(args[0] === 'popup__results') {
      const popupResults = document.querySelector('.popup__results');

      const divResult = document.createElement('div');
      divResult.className = 'popup__result';
      divResult.setAttribute('data-woeid', id);
      
      const spanResultName = document.createElement('span');
      spanResultName.className = 'popup__result-name';
      
      const cityReturn = document.createTextNode(args[1]);
      
      spanResultName.appendChild(cityReturn);
      
      divResult.appendChild(spanResultName);
      
      popupResults.prepend(divResult);
      
      return divResult;
    }
    
    if(args[0] === 'weather__search-ui') {
      const weatherUI = document.querySelector('.weather__search-ui');
      
      const divResult = document.createElement('div');
      divResult.className = 'weather__search-result';
      divResult.setAttribute('data-woeid', id);
      
      const spanResultName = document.createElement('span');
      const spanResultNameText = document.createTextNode(args[1]);
      spanResultName.className = 'weather__city-result';
      spanResultName.appendChild(spanResultNameText);
      
      const iconResult = document.createElement('i');
      iconResult.className = 'fa fa-arrow-right weather__go-result';
      
      repeatAppend([spanResultName, iconResult], divResult);
      
      weatherUI.appendChild(divResult);
      
      return divResult;
    }
  }
  
  // When click a coincidence in search field
  
  whenClickCoincidence(el) {
    const woeId = el.getAttribute('data-woeid');
    
    el.addEventListener('click', () => {
      let handler = 0;
      
      if(handler === 0) {
        getFetch(`https://www.metaweather.com/api/location/${woeId}/`)
          .then(res => res.json())
          .then(data => {
            const popup = document.querySelector('.popup');
            
            const weatherNext6Days = data.consolidated_weather;
            
            this.manageWeatherDashboardObj.changeWeatherBar(weatherNext6Days[0], data.title);
            
            weatherNext6Days.slice(1, 6).forEach(el => {
              this.manageWeatherDashboardObj.nextFiveDays(el);
            })
            
            this.manageWeatherDashboardObj.updateStadistics(weatherNext6Days[0]);
            
            popup.style.opacity = '0';
            popup.style.visibility = 'hidden';
          })
      }
      
      handler += 1;
    })
  }
}

export default popupPlugin;

Answer 1

当我将 redux 存储的导入语句移动到处理来自存储的一些减速器引用的本地模块的某个导入下方时，我遇到了同样的问题。向上移动 import store from ./store 为我解决了这个问题。

尝试修复文件中的导入顺序。

Answer 2

这可能是由循环依赖引起的（即模块A 导入模块B，反之亦然）。深入了解您的代码。