由于到useEffect结束时，inputValue已经被分配给previousInputValue.current，并且useEffect在组件的渲染或重新渲染期间运行，因此我认为第二个<h2>标记中的previousInputValue.current也应该与inputValue的值相同。但是，它如何能够显示先前的值？

export default function App() {
  const [inputValue, setInputValue] = useState("");
  const previousInputValue = useRef("");

  useEffect(() => {
    console.log(inputValue, previousInputValue.current); // ab ab,i think it should be "ab a"
    previousInputValue.current = inputValue;
    console.log("--", inputValue, previousInputValue.current); // ab ab 
  }, [inputValue]);

  return (
    <>
      <input
        type="text"
        value={inputValue}
        onChange={(e) => setInputValue(e.target.value)}
      />
      <h2>Current Value: {inputValue}</h2>  {/* ab */}
      <h2>Previous Value: {previousInputValue.current}</h2> {/*a i think it should be ab, as it is assigning inputValue in the useEffect()*/}
    </>
  );
}