Javascript 在NextJS中使用useState对象时,上下文对象为空
我试图在NextJS中传递一个上下文对象,该对象正在使用useState钩子中的数据,但是状态变量和setState函数在使用时是未定义的。这很奇怪,因为当我在它的位置传递一个简单的变量时,它工作得很好,只有在使用useState时它才是未定义的。所以我知道上下文对象正在工作,但是useState钩子没有 我的Javascript 在NextJS中使用useState对象时,上下文对象为空,javascript,reactjs,state,next.js,use-context,Javascript,Reactjs,State,Next.js,Use Context,我试图在NextJS中传递一个上下文对象,该对象正在使用useState钩子中的数据,但是状态变量和setState函数在使用时是未定义的。这很奇怪,因为当我在它的位置传递一个简单的变量时,它工作得很好,只有在使用useState时它才是未定义的。所以我知道上下文对象正在工作,但是useState钩子没有 我的\u app.js文件: import React from 'react'; import App from 'next/app'; import Head from 'next/hea
\u app.js
文件:
import React from 'react';
import App from 'next/app';
import Head from 'next/head';
import Aux from '../hoc/Aux';
import ContextProvider from '../context/context';
class MyApp extends App {
render() {
const { Component, pageProps } = this.props;
return (
<Aux>
<Head>
<title>MyApp</title>
</Head>
<ContextProvider>
<Component {...pageProps} />
</ContextProvider>
</Aux>
);
};
};
export default MyApp;
import React, { createContext, useState } from 'react';
export const Context = createContext();
const ContextProvider = (props) => {
const [ activeTab, setActiveTab ] = useState('OVERVIEW');
return (
<Context.Provider value={{ activeTab, setActiveTab }}>
{props.children}
</Context.Provider>
);
};
export default ContextProvider;
import styled from 'styled-components';
import { Context } from '../../context/context';
import { useContext } from 'react';
const Nav = () => {
const [activeTab, setActiveTab] = useContext(Context);
const TourNavUl = styled.ul`
`;
const TourNavLi = styled.li`
`;
return (
<NavUl>
<NavLi>
<span onClick={() => setActiveTab('OVERVIEW')}>Overview</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('ITINERARY')}>Itinerary</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('DETAILS')}>Details</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('BOOKINGS')}>Bookings</span>
</NavLi>
</NavUl>
);
};
export default Nav;
我的nav.js
文件:
import React from 'react';
import App from 'next/app';
import Head from 'next/head';
import Aux from '../hoc/Aux';
import ContextProvider from '../context/context';
class MyApp extends App {
render() {
const { Component, pageProps } = this.props;
return (
<Aux>
<Head>
<title>MyApp</title>
</Head>
<ContextProvider>
<Component {...pageProps} />
</ContextProvider>
</Aux>
);
};
};
export default MyApp;
import React, { createContext, useState } from 'react';
export const Context = createContext();
const ContextProvider = (props) => {
const [ activeTab, setActiveTab ] = useState('OVERVIEW');
return (
<Context.Provider value={{ activeTab, setActiveTab }}>
{props.children}
</Context.Provider>
);
};
export default ContextProvider;
import styled from 'styled-components';
import { Context } from '../../context/context';
import { useContext } from 'react';
const Nav = () => {
const [activeTab, setActiveTab] = useContext(Context);
const TourNavUl = styled.ul`
`;
const TourNavLi = styled.li`
`;
return (
<NavUl>
<NavLi>
<span onClick={() => setActiveTab('OVERVIEW')}>Overview</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('ITINERARY')}>Itinerary</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('DETAILS')}>Details</span>
</NavLi>
<NavLi>
<span onClick={() => setActiveTab('BOOKINGS')}>Bookings</span>
</NavLi>
</NavUl>
);
};
export default Nav;
从“样式化组件”导入样式化;
从“../../Context/Context”导入{Context};
从“react”导入{useContext};
常量导航=()=>{
const[activeTab,setActiveTab]=useContext(Context);
const TourNavUl=styled.ul`
`;
const TourNavLi=styled.li`
`;
返回(
setActiveTab('OVERVIEW')}>OVERVIEW
setActiveTab('行程')}>行程
setActiveTab('DETAILS')}>DETAILS
setActiveTab('BOOKINGS')}>BOOKINGS
);
};
导出默认导航;
这将返回错误TypeError:setActiveTab不是函数,因为它未定义。如前所述,如果我通过上下文传递一个简单变量,它工作正常,因此我知道它设置正确,但状态没有通过上下文对象
状态有什么问题吗?useContext
返回的是对象,而不是数组
而不是这个
const [activeTab, setActiveTab] = useContext(Context);
您应该具有以下功能:
const {activeTab, setActiveTab} = useContext(Context);