useRef和createRef有什么区别？

useRef和createRef有什么区别？

不同之处在于，

createRef

它将始终创建一个新的引用。在基于类的组件中，通常会在构造期间将ref放入实例属性（例如

this.input =createRef()

）。您在功能组件中没有此选项。

useRef

负责每次都返回与初始渲染相同的ref。

这是一个示例应用程序，演示了这两个功能的行为差异：

import React, { useRef, createRef, useState } from "react";import ReactDOM from "react-dom";function App() {  const [renderIndex, setRenderIndex] = useState(1);  const refFromUseRef = useRef();  const refFromCreateRef = createRef();  if (!refFromUseRef.current) {    refFromUseRef.current = renderIndex;  }  if (!refFromCreateRef.current) {    refFromCreateRef.current = renderIndex;  }  return (    <div className="App">      Current render index: {renderIndex}      <br />      First render index remembered within refFromUseRef.current:      {refFromUseRef.current}      <br />      First render index unsuccessfully remembered within      refFromCreateRef.current:      {refFromCreateRef.current}      <br />      <button onClick={() => setRenderIndex(prev => prev + 1)}>        Cause re-render      </button>    </div>  );}const rootElement = document.getElementById("root");ReactDOM.render(<App />, rootElement);