useEffect

useEffect 是一个 React Hook，它允许你 将组件与外部系统同步。

import { useState, useEffect } from "react";
import { fetchBio } from "./api.js";

export default function Page() {
  const [person, setPerson] = useState("Alice");
  const [bio, setBio] = useState(null);

  useEffect(() => {
    let ignore = false;
    setBio(null);

    fetchBio(person).then((result) => {
      if (!ignore) {
        setBio(result);
      }
    });

    return () => {
      ignore = true;
    };
  }, [person]);
}