Reactjs 关于forwardRef，我可以'；我不理解第二个用例

Case I, I can accept those code as the picture shows, we define the ref in parent component and pass it to child component个

App.js

import { useRef } from 'react';
import MyInput from './MyInput.js';

export default function Form() {
  const ref = useRef(null);

  function handleClick() {
    ref.current.focus();
  }

  return (
    <form>
      <MyInput label="Enter your name:" ref={ref} />
      <button type="button" onClick={handleClick}>
        Edit
      </button>
    </form>
  );
}

MyInput.js

import { forwardRef } from 'react';

const MyInput = forwardRef(function MyInput(props, ref) {
  const { label, ...otherProps } = props;
  return (
    <label>
      {label}
      <input {...otherProps} ref={ref} />
    </label>
  );
});

export default MyInput;

Case II,the component Input was defined as following ,个

import * as React from 'react'

import { cn } from '@/lib/utils'

export interface InputProps
  extends React.InputHTMLAttributes<HTMLInputElement> {}

const Input = React.forwardRef<HTMLInputElement, InputProps>(
  ({ className, type, ...props }, ref) => {
    return (
      <input
        type={type}
        className={cn(
          'flex h-9 w-full rounded-md border border-input bg-transparent px-3 py-2 text-sm shadow-sm ring-offset-background file:border-0 file:bg-transparent file:text-sm file:font-medium placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50',
          className
        )}
        ref={ref}
        {...props}
      />
    )
  }
)
Input.displayName = 'Input'

export { Input }

这是在另一个文件chat.js中使用的，剧集ID如下

import { Input } from './ui/input'

<Input
        value={previewTokenInput}
        placeholder="OpenAI API key"
        onChange={e => setPreviewTokenInput(e.target.value)}
/>

有些事情把我搞糊涂了，父级没有定义Ref变量，直接使用.这是使用ForwardRef的新方法吗？

代码是从https://github.com/vercel-labs/ai-chatbot开始，

• /Component/chat.tsx
• /Component/ui/input.tsx