使用 Hooks 在 React 中重新渲染时停止/防止滚动到顶部（需要实现无限滚动）

Question

我正在尝试使用React Hooks设置无限滚动，我从节点后端正确获取数据（每个请求 3 个数据集），并且当我滚动时，新数据也正确添加到数组中（在加载位置状态），但是页面在重新渲染时返回顶部，我需要防止这种行为。 我如何防止这种情况，下面是我的代码

import React, { useEffect, useState } from "react";
import "./App.css";

function App() {
  const [page, setPage] = useState(1);
  const [loadedPlaces, setLoadedPlaces] = useState([]);
  const [isLoading, setIsLoading] = useState(false);

  useEffect(() => {
    const getPlaces = async () => {
      try {
        setIsLoading(true);
        const url = `http://localhost:5000/api/places/user/${id}?page=${page}&size=3`;
        const responseData = await fetch(url);
        const data = await responseData.json();
        console.log(data);
        setLoadedPlaces((prev) => [...prev, ...data.places]);
        setIsLoading(false);
      } catch (error) {}
    };
    getPlaces();
  }, [page]);

  window.onscroll = function (e) {
    if (
      window.innerHeight + document.documentElement.scrollTop ===
      document.documentElement.offsetHeight
    ) {
      setPage(page + 1);
    }
  };

  return (
    <div className='App'>
      <h1>Infinite Scroll</h1>
      {!isLoading &&
        loadedPlaces.length > 0 &&
        loadedPlaces.map((place, index) => (
          <div key={index} className={"container"}>
            <h1>{place.location.lat}</h1>
            <h1>{place.location.lng}</h1>
            <h1>{place.title}</h1>
            <h1>{place.description}</h1>
            <h1>{place.address}</h1>
            <hr></hr>
          </div>
        ))}
    </div>
  );
}

export default App;

任何帮助都受到高度赞赏

Answer 1

发生这种情况是因为每当您滚动时，您都会打电话

window.onscroll = function (e) {
    if (
      window.innerHeight + document.documentElement.scrollTop ===
      document.documentElement.offsetHeight
    ) {
      setPage(page + 1);
    }
  };

它正在改变页数，改变的页数会导致再次运行

 useEffect(() => {
    const getPlaces = async () => {
      try {
        setIsLoading(true);
        const url = `http://localhost:5000/api/places/user/${id}?page=${page}&size=3`;
        const responseData = await fetch(url);
        const data = await responseData.json();
        console.log(data);
        setLoadedPlaces((prev) => [...prev, ...data.places]);
        setIsLoading(false);
      } catch (error) {}
    };
    getPlaces();
  }, [page]);

在该函数中，您正在执行setIsLoading(true)以便它再次呈现它，因为

{!isLoading && <-----
        loadedPlaces.length > 0 &&
        loadedPlaces.map((place, index) => (
          <div key={index} className={"container"}>
            <h1>{place.location.lat}</h1>
            <h1>{place.location.lng}</h1>
            <h1>{place.title}</h1>
            <h1>{place.description}</h1>
            <h1>{place.address}</h1>
            <hr></hr>
          </div>
        ))}

这会将您带到页面顶部

你可以试试这个方法：

import React, { useEffect, useState } from "react";
import "./App.css";

function App() {
  const [page, setPage] = useState(1);
  const [loadedPlaces, setLoadedPlaces] = useState([]);
  const [isLoading, setIsLoading] = useState(false);

  useEffect(() => {
    const getPlaces = async () => {
      try {
        setIsLoading(true);
        const url = `http://localhost:5000/api/places/user/${id}?page=${page}&size=3`;
        const responseData = await fetch(url);
        const data = await responseData.json();
        console.log(data);
        setLoadedPlaces((prev) => [...prev, ...data.places]);
        setIsLoading(false);
      } catch (error) {}
    };
    getPlaces();
  }, [page]);

  window.onscroll = function (e) {
    if (
      window.innerHeight + document.documentElement.scrollTop ===
      document.documentElement.offsetHeight
    ) {
      setPage(page + 1);
    }
  };

  return (
    <div className='App'>
      <h1>Infinite Scroll</h1>
       {
        loadedPlaces.length > 0 &&
        loadedPlaces.map((place, index) => (
          <div key={index} className={"container"}>
            <h1>{place.location.lat}</h1>
            <h1>{place.location.lng}</h1>
            <h1>{place.title}</h1>
            <h1>{place.description}</h1>
            <h1>{place.address}</h1>
            <hr></hr>
          </div>
        ))}
    </div>
  );
}

export default App;

Answer 2

你可以添加这个。

function ScrollToBottom(){
  const elementRef = useRef();
  useEffect(() => elementRef.current.scrollIntoView());
  return <div ref={elementRef} />;
};

接着：

return (
    <div className='App'>
      <h1>Infinite Scroll</h1>
      {!isLoading &&
        loadedPlaces.length > 0 &&
        loadedPlaces.map((place, index) => (
          <div key={index} className={"container"}>
            <h1>{place.location.lat}</h1>
            <h1>{place.location.lng}</h1>
            <h1>{place.title}</h1>
            <h1>{place.description}</h1>
            <h1>{place.address}</h1>
            <hr></hr>
          </div>
        ))}
      <ScrollToBottom /> 
    </div>
  );