![](/img/trans.png)
[英]How do I update state of a functional component from a class component in order to display items from a map in react
[英]How do I use context to share state between a class and a functional component in react?
我有一个顶级上下文提供程序,其次是一个父类组件,然后是一个功能性无状态子级。
我可以从“子级”更新我的上下文值,但不能从父级更新,即使该值在父级中更新。
如何使用上下文更新和共享两个组件之间的状态?
import React from "react";
import ReactDOM from "react-dom";
const Context = React.createContext();
const Provider = ({ children }) => {
const [value, setValue] = React.useState(0);
return (
<Context.Provider value={{ value, setValue }}>{children}</Context.Provider>
);
};
const Child = () => {
const { value, setValue } = React.useContext(Context);
return <div onClick={() => setValue(value + 1)}>Plus plus!!</div>;
};
class Parent extends React.Component {
render() {
const { value, setValue } = this.context;
return (
<div>
<div onPress={() => setValue(value - 1)}>MINUS MINUS!</div>
<div>{this.props.children}</div>
<h1>{value}</h1>
</div>
);
}
}
Parent.contextType = Context;
function App() {
return (
<Provider>
<Parent>
<Child />
</Parent>
</Provider>
);
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
将“ onPress”更改为“ onClick”即可使用。 我已经测试过了
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.