Reactjs 反应上下文不工作:未定义无未定义
为什么我的上下文在React中不起作用?收到下面未定义的错误Reactjs 反应上下文不工作:未定义无未定义,reactjs,Reactjs,为什么我的上下文在React中不起作用?收到下面未定义的错误 import React, { useContext } from 'react'; function BookList() { const PrintContext = React.createContext("CAR"); const list = [ { title: 'ABCDE', author: 'John Smith' } ] return ( <Prin
import React, { useContext } from 'react';
function BookList() {
const PrintContext = React.createContext("CAR");
const list = [
{ title: 'ABCDE', author: 'John Smith' }
]
return (
<PrintContext.Provider value="APPLE">
<ul>
{list.map((book, i) => <Book title={book.title} author={book.author} key={i} />)}
</ul>
</PrintContext.Provider>
)
}
function Book(props) {
const theme = useContext(PrintContext)
return (
<li>
<h2>{theme}</h2>
<h2>{props.title}</h2>
<div>{props.author}</div>
<input value={props.year} />
</li>
)
}
import React,{useContext}来自“React”;
函数BookList(){
const PrintContext=React.createContext(“CAR”);
常数列表=[
{标题:'ABCDE',作者:'John Smith'}
]
返回(
{list.map((book,i)=>)}
)
}
功能书(道具){
const theme=useContext(PrintContext)
返回(
{主题}
{props.title}
{props.author}
)
}
接收错误:
未定义“PrintContext”无未定义
使用最新版本的React
资源:
将您的打印上下文置于
图书列表
功能范围之外
import React, { useContext } from 'react';
const PrintContext = React.createContext("CAR");
function BookList() {
const list = [
{ title: 'ABCDE', author: 'John Smith' }
]
return (
<PrintContext.Provider value="APPLE">
<ul>
{list.map((book, i) => <Book title={book.title} author={book.author} key={i} />)}
</ul>
</PrintContext.Provider>
)
}
function Book(props) {
const theme = useContext(PrintContext)
return (
<li>
<h2>{theme}</h2>
<h2>{props.title}</h2>
<div>{props.author}</div>
<input value={props.year} />
</li>
)
}
import React,{useContext}来自“React”;
const PrintContext=React.createContext(“CAR”);
函数BookList(){
常数列表=[
{标题:'ABCDE',作者:'John Smith'}
]
返回(
{list.map((book,i)=>)}
)
}
功能书(道具){
const theme=useContext(PrintContext)
返回(
{主题}
{props.title}
{props.author}
)
}
将打印上下文置于图书列表
功能范围之外
import React, { useContext } from 'react';
const PrintContext = React.createContext("CAR");
function BookList() {
const list = [
{ title: 'ABCDE', author: 'John Smith' }
]
return (
<PrintContext.Provider value="APPLE">
<ul>
{list.map((book, i) => <Book title={book.title} author={book.author} key={i} />)}
</ul>
</PrintContext.Provider>
)
}
function Book(props) {
const theme = useContext(PrintContext)
return (
<li>
<h2>{theme}</h2>
<h2>{props.title}</h2>
<div>{props.author}</div>
<input value={props.year} />
</li>
)
}
import React,{useContext}来自“React”;
const PrintContext=React.createContext(“CAR”);
函数BookList(){
常数列表=[
{标题:'ABCDE',作者:'John Smith'}
]
返回(
{list.map((book,i)=>)}
)
}
功能书(道具){
const theme=useContext(PrintContext)
返回(
{主题}
{props.title}
{props.author}
)
}
hi@PrãtêkThápá它起作用了,请随意回答,我可以给你打分,谢谢!正常的JavaScript购物仍然适用。hi@PrãtêkThápá它可以工作,请随意填写答案,我可以发送积分,谢谢!正常的JavaScript购物仍然适用。