javascript - 在渲染中使用不同的 html 元素时如何将 React.forwardRef 与 TypeScript 结合使用

Question

我正在努力处理那个显示跨度或 <br> 的非常简单的组件。取决于 Prop :

import * as React from 'react';

type Props = {value: string}

function LetterRenderer({value = ''}: Props, ref: React.Ref<HTMLElement>) {
    switch(value) {
      case '\n': return (<br ref={ref} />);
      default: return (<span ref={ref}>{value}</span>);
    }
}

const Letter = React.forwardRef<HTMLElement, Props>(LetterRenderer);
Letter.displayName = 'Letter';
export default Letter;

关于 <br ref={ref} /> ，第二个ref带有下划线并带有以下错误消息:

Type 'Ref<HTMLElement>' is not assignable to type 'string | ((instance: HTMLBRElement | null) => void) | RefObject<HTMLBRElement> | null | undefined'.
  Type 'RefObject<HTMLElement>' is not assignable to type 'string | ((instance: HTMLBRElement | null) => void) | RefObject<HTMLBRElement> | null | undefined'.
    Type 'RefObject<HTMLElement>' is not assignable to type 'RefObject<HTMLBRElement>'.
      Property 'clear' is missing in type 'HTMLElement' but required in type 'HTMLBRElement'.ts(2322)
lib.dom.d.ts(6336, 5): 'clear' is declared here.
index.d.ts(106, 9): The expected type comes from property 'ref' which is declared here on type 'DetailedHTMLProps<HTMLAttributes<HTMLBRElement>, HTMLBRElement>'

我应该如何解决这个问题？

Answer 1

function LetterRenderer({value = ''}: Props, ref: React.Ref<HTMLElement>) {
// ...

您的 ref 属性接受 HTMLElement但你真正想要的是 HTMLBRElement | HTMLSpanElement因为ref被传递到 <br>和<span>谁是ref属性是React.Ref<HTMLBRElement>和React.Ref<HTMLSpanElement>分别。

将 ref 属性更改为

ref: React.Ref<HTMLBRElement | HTMLSpanElement>

请注意HTMLBRElement和HTMLSpanElement两者都继承HTMLElement但反之则不然； HTMLElement没有clear属性但是 HTMLBRElement做。

更新:

因为<br>的和<span>的ref属性仅接受 React.Ref<HTMLBRElement>和React.Ref<HTMLSpanElement>分别是ref需要相应地进行内联转换。

<br ref={ref as React.Ref<HTMLBRElement>} />

<span ref={ref as React.Ref<HTMLSpanElement>}>{text}</span>