javascript - 类型错误 : Object is not iterable (cannot read property Symbol(Symbol. 迭代器))

Question

我尝试运行这段代码，但它给我一个运行时错误提示

TypeError: Object is not iterable (cannot read propertySymbol(Symbol.iterator))

这是代码。

import React, { useContext} from "react";
import { GlobalContext } from '../GlobalState';

const MediaCard = ({ songs, categotyTitle }) => {
  const [{}, dispatch] = useContext(GlobalContext);
  const setCurrentVideoSnippet = data => {
    dispatch({ type: "setCurrentVideoSnippet", snippet: data });
  };
export default MediaCard;

错误指向这行代码 const [{}, dispatch] = useContext(GlobalContext);

GlobalState 代码

import React, { useReducer } from "react";

export const GlobalContext = React.createContext();

const initialState = {
  currentVideoSnippet: {}, 
};

const reducer = (state, action) => {
  switch (action.type) {
    case "setCurrentVideoSnippet":
      return {
        ...state,
        currentVideoSnippet: action.snippet
      };
 default:
      return state;
  }
};

export const GlobalState = props => {
  const globalState = useReducer(reducer, initialState);
  return (
    <GlobalContext.Provider value={globalState}>
      {props.children}
    </GlobalContext.Provider>
  );
};

Answer 1

我知道这并不能解决 OP 的问题，但对于像我一样最终在这个页面上看到相同运行时错误消息的人来说，我的问题是由于我导入 GlobalContext 组件的方式造成的。

错误的方式:从“../GlobalState”导入 GlobalContext；

正确的方法:从 '../GlobalState' 导入 { GlobalContext };

这解决了我遇到的相同错误消息的问题。