一旦安装了应用程序,就会呈现这些组件(原因是,这些组件需要插入到获取的纯HTML中)
我看到状态已更改,但是元素对此没有反应
有什么解决方法吗?
import React, { useEffect, useState } from "react";
import ReactDOM from "react-dom";
export default function App() {
const [elements, setElements] = useState("none");
useEffect(() => {
console.log("global useEffect: " + elements);
}, [elements]);
const Input = ({ setElements }) => (
<>
<input
type="text"
onChange={e => {
setElements(e.target.value);
}}
/>
<div>{elements}</div>
</>
);
const Elements = ({ elements }) => {
useEffect(() => {
console.log("Elements useEffect: " + elements);
}, [elements]);
return <span>{elements}</span>;
};
const Elements2 = ({ elements }) => <span>{elements}</span>;
useEffect(() => {
console.log("useEffect first time");
ReactDOM.render(
<Elements elements={elements} />,
document.getElementById("elements")
);
ReactDOM.render(
<Elements2 elements={elements} />,
document.getElementById("elements2")
);
ReactDOM.render(
<Input setElements={setElements} />,
document.getElementById("inputId")
);
}, []);
// need to split plainhtml, otherwise codesandbox
// ...gives an error that is IMO a bug
const plainhtml1 = `
<div>
<div>This plain html has been fetched</div>
<div id="inputId" />
</div>
`;
const plainhtml2 = `
<div>
<div>number of elements:</div>
<div id="elements" />
</div>
`;
const plainhtml3 = `
<div>
<div>number of other elements:</div>
<div id="elements2" />
</div>
`;
return (
<div>
<h1>Hello CodeSandbox</h1>
<div dangerouslySetInnerHTML={{ __html: plainhtml1 }} />
<div dangerouslySetInnerHTML={{ __html: plainhtml2 }} />
<div dangerouslySetInnerHTML={{ __html: plainhtml3 }} />
</div>
);
}
元素不知道App
状态在更改时会更改。通过使用这样的效果来告诉他们有关更改的信息:
useEffect(() => {
ReactDOM.render(
<Elements elements={elements} />,
document.getElementById("elements")
);
ReactDOM.render(
<Elements2 elements={elements} />,
document.getElementById("elements2")
);
ReactDOM.render(
<Input setElements={setElements} />,
document.getElementById("inputId")
);
}, [elements, setElement]);
[React将在elements
和setElements
值每次更改时调用效果(并因此重新渲染元素)。实际上,由于效果非常相似,您只需将elements
添加到其依赖项列表(第二个参数中的数组)。