Question 74220 in Reactjs Question posted in
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createContext undefined – Reactjs

When I try to use createContext() the console gives me this error:

App.js:6
Uncaught TypeError: Cannot destructure property 'consoleLogFunction' of '(0 , react__WEBPACK_IMPORTED_MODULE_1__.useContext)(...)' as it is null.

I’ve seen others asking questions about this here in Stack Overflow but I can’t find a solution.

GlobalContext.js

import React from 'react'
import { createContext } from 'react'

export const AppContext = createContext();

function GlobalContext() {
    const consoleLogFunction = () => {
        console.log("ok")
    }
    return (
        <AppContext.Provider value={{consoleLogFunction}}></AppContext.Provider>
    )
}

export default GlobalContext

App.js

import "./index.css";
import { useContext, useEffect } from "react";
import { AppContext } from "./components/GlobalContext";

function App() {
  const { consoleLogFunction } = useContext(AppContext);
  useEffect(() => {
    consoleLogFunction();
  }, []);

  return (
    <AppContext>
      <div>home</div>
    </AppContext>
  );
}

export default App;
Tags:

2

Answers


  1. 0

    hello man the problem is because App component is not wrapped inside GlobalContext . and in the GlobalContext component you should handle the children prop.

    it will work when doing it like this example :

    import { useEffect, useContext, createContext } from "react";
import "./styles.css";

export const AppContext = createContext();

function GlobalContext(props) {
  const consoleLogFunction = () => {
    console.log("ok");
  };
  return (
    <AppContext.Provider value={{ consoleLogFunction }}>
      {props.children}
    </AppContext.Provider>
  );
}

const Home = () => {
  const { consoleLogFunction } = useContext(AppContext);
  useEffect(() => {
    consoleLogFunction();
  }, []);

  return <div>home</div>;
};

export default function App() {
  return (
    <GlobalContext>
      <Home />
    </GlobalContext>
  );
}

    Hope this help.

    Login or Signup to reply.
  2. 0

    You don’t need to export ‘AppContext’, creating the provider and exporting that is good enough.

    Try this, I’ve also made a couple of modifications to make it easier to use the context later:

    GlobalContext.js

    import React from 'react'
import { createContext, useContext } from 'react'

const AppContext = createContext();

function GlobalContext({ children }) {
    const consoleLogFunction = () => {
        console.log("ok")
    }
    return (
      <AppContext.Provider value={{consoleLogFunction}}>
        { children }
      </AppContext.Provider>
    )
}

export default GlobalContext;

// This is a helper
export const useGlobalContext = () => useContext(AppContext);

    Home.js

    import { useEffect } from "react";
import { useGlobalContext } from "./components/GlobalContext";

export const Home = ({ children }) => {
  const { consoleLogFunction } = useGlobalContext();

  useEffect(() => {
    consoleLogFunction();
  }, []);  

  return(
    <div>home</div>
  )
};

    App.js

    import "./index.css";
import { useEffect } from "react";
import GlobalContext from "./components/GlobalContext"
import { Home } from "./components/Home";

function App() {
  return(
    <GlobalContext>
      <Home />
    </GlobalContext>
  );
}

export default App;
    Login or Signup to reply.
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