反应："Can't perform a React state update on an unmounted component" 没有 useEffect 函数

Question

（我正在使用 Next.js + Styled Components，我完全是个初学者，请帮助我 :)）

我正在开发一种“Netflix”页面，其中包含不同类型的目录组件。页面网格中的每个内容都是一个非常复杂的组件，有很多交互，称为 ContentItem.js，在 ContentList.js 中重复。

所以，我收到了这个错误：

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
    at ContentItem (webpack-internal:///./ltds/components/Shelf/ContentItem.js:104:62)
    at ul
    at O (webpack-internal:///./node_modules/styled-components/dist/styled-components.browser.esm.js:31:19797)
    at ContentList (webpack-internal:///./ltds/components/Shelf/ContentList.js:52:23)
    at div
    at O (webpack-internal:///./node_modules/styled-components/dist/styled-components.browser.esm.js:31:19797)
    at Shelf (webpack-internal:///./ltds/components/Shelf/Shelf.js:57:66)
    at div
    at SearchResult (webpack-internal:///./pages/search/[term].js:32:70)

但是，在这个组件中，我没有使用 useEffect:

import Image from 'next/image';
import { Paragraph } from '../../styles/Typography';
import styled from 'styled-components';
import { gridUnit } from '../../styles/GlobalStyle';
import { useEffect, useState } from 'react'; 
import { Transition } from 'react-transition-group';
import React from 'react';
import Icon from '../Icon';

const ContentItemContainer = styled.li`
  margin-bottom: 16px;
  text-decoration: none;
  transition: all 0.2s;
  position: relative;
  border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  overflow: hidden;
  height: auto;

  &:hover {
    cursor: pointer;
    transform: ${props => (props.isClicking ? "scale(0.98)" : "scale(1.04)")};
  }
`;
const ItemCover = styled(Image)`
  
  border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  border: 1px solid #504F4E;
  overflow: visible;
  position: relative;

  transition: 0.2s;
  opacity: ${({ state }) => (state === "entering" ? 0 : 1)};
`;

const ItemHoverContainer = styled.div`
  position: absolute;
  z-index: 10;
  top: 0;
  left: 0;
  right: 0;
  padding: 0px;
  margin: 0px;
  height: auto;

  &:hover{
    border: 0.8px solid ${props => (props.theme.alias.image.border.value)};
    border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  }
  
`;

const ItemHoverImage = styled(Image)`
  border-radius: 15px; //15px not 16px: hack to avoid a "phantom line" at the bottom of image

  transition: 0.4s;
  display: ${({ state }) => (state === "exited" ? "none" : "block")};
  opacity: ${({ state }) => (state === "entered" ? 1 : 0)};
 
`;

const IconContainer = styled.div`
  position: absolute;
  left: 41.84%;
  right: 41.13%;
  top: 42.58%;
  bottom: 42.11%;
`;
const DetailsContainer = styled(Paragraph)`

  padding-top: ${({ state }) => (state === "entered" ? props => props.theme.spacing[1].value+gridUnit : 0)};
  transition: 0.4s;
  opacity: ${({ state }) => (state === "entered" ? 1 : 0)};
  height: ${({ state }) => (state === "entered" ? 1 : 0)};
  display: ${({ state }) => (state === "exited" ? "none" : "block")};
  
`;

function ContentItem(props) {

  const nodeRef = React.useRef(null);
  const [isHovering, setIsHovering] = useState(false);
  const [isClicking, setIsClicking] = useState(false);
  const [isLoaded, setIsLoaded] = useState(false);

  const coverSizes = {
    wide:{
      width: 236, 
      height:139
    },
    poster:{
      width: 144, 
      height: 192
    }
  }

  function handleMouseOver(event) {
    setIsHovering(!isHovering)
  }
  function handleMouseOut(event) {
    setIsHovering(!isHovering)
  }

  function handleMouseDown(event) {
    setIsClicking(!isClicking)
  }
  function handleMouseUp(event) {
    setIsClicking(!isClicking)
  }
  function handleLoadingComplete(event) {
    !isLoaded && (setIsLoaded(true))
  }

  return (
    
    <ContentItemContainer isClicking={isClicking} onMouseOver={handleMouseOver} onMouseOut={handleMouseOut} onMouseDown={handleMouseDown} onMouseUp={handleMouseUp}>
      <Transition in={isLoaded} timeout={0} nodeRef={nodeRef}>
      {(state) => ( <div>
        <ItemCover 
            src={props.coverType == "wide" ? props.wideCover : props.posterCover } 
            alt={props.alt} 
            layout={'responsive'}   
            width={props.coverType == "wide" ? coverSizes.wide.width : coverSizes.poster.width} 
            height={props.coverType == "wide" ? coverSizes.wide.height+1 : coverSizes.poster.height}//+1: hack to avoid cut at the bottom of image
            placeholder='blur'
            blurDataURL={props.coverPlaceholder}
            onLoadingComplete={handleLoadingComplete}  
        />
        </div>)}
      </Transition>

      <ItemHoverContainer>
        <Transition in={isHovering} timeout={0} nodeRef={nodeRef} mountOnEnter unmountOnExit>
          {(state) => (
          <div>
            <ItemHoverImage 
              src={props.coverType == "wide" ? props.wideLoopVideo : props.posterLoopVideo }
              layout={'responsive'} 
              width={props.coverType == "wide" ? coverSizes.wide.width : coverSizes.poster.width} 
              height={props.coverType == "wide" ? coverSizes.wide.height : coverSizes.poster.height+1} //+1: hack to avoid a "phantom line" at the bottom of image
              state={state}
            />
            <IconContainer>
              <Icon preserveAspectRatio="xMinYMin meet" name="coverPlay"/>
              </IconContainer>
          </div>
          )}  
        </Transition>
      </ItemHoverContainer>


      <Transition in={props.isDetailed} timeout={100} nodeRef={nodeRef}>
        {(state) => (
          <DetailsContainer state={state} isDetailed={props.isDetailed}>{props.content.details}</DetailsContainer>
        )}
      </Transition>
      

    </ContentItemContainer>

  );
  }

  export default ContentItem

我该如何解决这个问题？

更新

我尝试使用基于@MB_答案的useEffect，但内存泄漏错误仍然发生：

import React, { useState, useRef, useEffect } from 'react';
import Image from 'next/image';
import { Transition } from 'react-transition-group';
import styled from 'styled-components';
import { Paragraph } from '../../styles/Typography';
import { gridUnit } from '../../styles/GlobalStyle';

import Icon from '../Icon';

function ContentItem(props) {

  const [isHovering, setIsHovering] = useState(false);
  const [isClicking, setIsClicking] = useState(false);
  const [isLoaded, setIsLoaded] = useState(false);

  const nodeRef = useRef(null);
  const mouseRef = useRef(null);
  const imgRef = useRef(null);

  useEffect(() => {

    const currentMouseRef = mouseRef.current;
    
    if (currentMouseRef) {
      currentMouseRef.addEventListener('mouseover', handleMouseOver);
      currentMouseRef.addEventListener('mouseout', handleMouseOut);
      currentMouseRef.addEventListener('mousedown', handleMouseDown);
      currentMouseRef.addEventListener('mouseup', handleMouseUp);

      return () => {
        currentMouseRef.removeEventListener('mouseover', handleMouseOver);
        currentMouseRef.removeEventListener('mouseout', handleMouseOut);
        currentMouseRef.removeEventListener('mousedown', handleMouseDown);
        currentMouseRef.removeEventListener('mouseup', handleMouseUp);
      };
    }
  }, []);

  const handleMouseOver = () => setIsHovering(true);
  const handleMouseOut = () => setIsHovering(false);
  const handleMouseDown = () => setIsClicking(true);
  const handleMouseUp = () => setIsClicking(false);

  const handleLoadingComplete = () => !isLoaded && setIsLoaded(true);

  const coverSizes = {
    wide:{
      width: 236, 
      height:139
    },
    poster:{
      width: 144, 
      height: 192
    }
  }

  return (
    
    <ContentItemContainer 
      ref={mouseRef} 
      onMouseOver={handleMouseOver} 
      onMouseOut={handleMouseOut} 
      onMouseDown={handleMouseDown} 
      onMouseUp={handleMouseUp}
      isClicking={isClicking} 
    >
      <Transition in={isLoaded} timeout={0} nodeRef={nodeRef}>
      {(state) => ( <div>
        <ItemCover 
            src={props.coverType == "wide" ? props.wideCover : props.posterCover } 
            alt={props.alt} 
            layout={'responsive'}   
            width={props.coverType == "wide" ? coverSizes.wide.width : coverSizes.poster.width} 
            height={props.coverType == "wide" ? coverSizes.wide.height+1 : coverSizes.poster.height}//+1: hack to avoid cut at the bottom of image
            placeholder='blur'
            blurDataURL={props.coverPlaceholder}
            onLoadingComplete={handleLoadingComplete}  
        />
        </div>)}
      </Transition>

      <ItemHoverContainer>
        <Transition in={isHovering} timeout={0} nodeRef={nodeRef} mountOnEnter unmountOnExit>
          {(state) => (
          <div>
            <ItemHoverImage 
              src={props.coverType == "wide" ? props.wideLoopVideo : props.posterLoopVideo }
              layout={'responsive'} 
              width={props.coverType == "wide" ? coverSizes.wide.width : coverSizes.poster.width} 
              height={props.coverType == "wide" ? coverSizes.wide.height : coverSizes.poster.height+1} //+1: hack to avoid a "phantom line" at the bottom of image
              state={state}
            />
            <IconContainer>
              <Icon preserveAspectRatio="xMinYMin meet" name="coverPlay"/>
              </IconContainer>
          </div>
          )}  
        </Transition>
      </ItemHoverContainer>


      <Transition in={props.isDetailed} timeout={100} nodeRef={nodeRef}>
        {(state) => (
          <DetailsContainer state={state} isDetailed={props.isDetailed}>{props.content.details}</DetailsContainer>
        )}
      </Transition>
      

    </ContentItemContainer>

  );
  }

  export default ContentItem

  const ContentItemContainer = styled.li`
  margin-bottom: 16px;
  text-decoration: none;
  transition: all 0.2s;
  position: relative;
  border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  overflow: hidden;
  height: auto;

  &:hover {
    cursor: pointer;
    transform: ${props => (props.isClicking ? "scale(0.98)" : "scale(1.04)")};
  }
`;
const ItemCover = styled(Image)`
  
  border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  border: 1px solid #504F4E;
  overflow: visible;
  position: relative;

  transition: 0.2s;
  opacity: ${({ state }) => (state === "entering" ? 0 : 1)};
`;

const ItemHoverContainer = styled.div`
  position: absolute;
  z-index: 10;
  top: 0;
  left: 0;
  right: 0;
  padding: 0px;
  margin: 0px;
  height: auto;

  &:hover{
    border: 0.8px solid ${props => (props.theme.alias.image.border.value)};
    border-radius: ${(props => props.theme.radius.lg.value)}${gridUnit};
  }
  
`;

const ItemHoverImage = styled(Image)`
  border-radius: 15px; //15px not 16px: hack to avoid a "phantom line" at the bottom of image

  transition: 0.4s;
  display: ${({ state }) => (state === "exited" ? "none" : "block")};
  opacity: ${({ state }) => (state === "entered" ? 1 : 0)};
 
`;

const IconContainer = styled.div`
  position: absolute;
  left: 41.84%;
  right: 41.13%;
  top: 42.58%;
  bottom: 42.11%;
`;
const DetailsContainer = styled(Paragraph)`

  padding-top: ${({ state }) => (state === "entered" ? props => props.theme.spacing[1].value+gridUnit : 0)};
  transition: 0.4s;
  opacity: ${({ state }) => (state === "entered" ? 1 : 0)};
  height: ${({ state }) => (state === "entered" ? 1 : 0)};
  display: ${({ state }) => (state === "exited" ? "none" : "block")};
  
`;

Answer 1

使用EventListeners

时需要useEffect

// (1)
import React, { useState, useRef, useEffect } from 'react';
import Image from 'next/image';
import { Transition } from 'react-transition-group';
import styled from 'styled-components';
import { Paragraph } from '../../styles/Typography';
import { gridUnit } from '../../styles/GlobalStyle';

import Icon from '../Icon';

export default function ContentItem(props) {                 // (2)
  const [isHovering, setIsHovering] = useState(false);
  const [isClicking, setIsClicking] = useState(false);
  const [isLoaded, setIsLoaded] = useState(false);

  const nodeRef = useRef(null);
  const mouseRef = useRef(null);               // create another ref for mouse listener


  useEffect(() => {
    if (mouseRef.current) {
      mouseRef.current.addEventListener('mouseover', handleMouseOver);
      mouseRef.current.addEventListener('mouseout', handleMouseOut);

      return () => {
        mouseRef.current.removeEventListener('mouseover', handleMouseOver);
        mouseRef.current.removeEventListener('mouseout', handleMouseOut);
      };
    }
  }, [mouseRef.current]);


  const handleMouseOver = () => setIsHovering(true);
  const handleMouseOut = () => setIsHovering(false);
  const toggleClick = () => setIsClicking(!isClicking);
  const handleLoadingComplete = () => !isLoaded && setIsLoaded(true);


  const coverSizes = {
    wide: {
      width: 236,
      height: 139,
    },
    poster: {
      width: 144,
      height: 192,
    },
  };

  return (
    <ContentItemContainer ref={mouseRef} onClick={toggleClick}>     // ref + onClick
      <Transition in={isLoaded} timeout={0} nodeRef={nodeRef}>
        {(state) => (                                               // state ?
          <div>
            <ItemCover
              src={
                props.coverType == 'wide' ? props.wideCover : props.posterCover
              }
              alt={props.alt}
              layout={'responsive'}
              width={
                props.coverType == 'wide'
                  ? coverSizes.wide.width
                  : coverSizes.poster.width
              }
              height={
                props.coverType == 'wide'
                  ? coverSizes.wide.height + 1
                  : coverSizes.poster.height
              } //+1: hack to avoid cut at the bottom of image
              placeholder="blur"
              blurDataURL={props.coverPlaceholder}
              onLoadingComplete={handleLoadingComplete}
            />
          </div>
        )}
      </Transition>

      <ItemHoverContainer>
        <Transition
          in={isHovering}
          timeout={0}
          nodeRef={nodeRef}
          mountOnEnter
          unmountOnExit
        >
          {(state) => (
            <div>
              <ItemHoverImage
                src={
                  props.coverType == 'wide'
                    ? props.wideLoopVideo
                    : props.posterLoopVideo
                }
                layout={'responsive'}
                width={
                  props.coverType == 'wide'
                    ? coverSizes.wide.width
                    : coverSizes.poster.width
                }
                height={
                  props.coverType == 'wide'
                    ? coverSizes.wide.height
                    : coverSizes.poster.height + 1
                } //+1: hack to avoid a "phantom line" at the bottom of image
                state={state}
              />
              <IconContainer>
                <Icon preserveAspectRatio="xMinYMin meet" name="coverPlay" />
              </IconContainer>
            </div>
          )}
        </Transition>
      </ItemHoverContainer>

      <Transition in={props.isDetailed} timeout={100} nodeRef={nodeRef}>
        {(state) => (
          <DetailsContainer state={state} isDetailed={props.isDetailed}>
            {props.content.details}
          </DetailsContainer>
        )}
      </Transition>
    </ContentItemContainer>
  );
}

// styled components
const ContentItemContainer = styled.li`
  margin-bottom: 16px;
  text-decoration: none;
  transition: all 0.2s;
  position: relative;
  border-radius: ${(props) => props.theme.radius.lg.value} ${gridUnit};
  overflow: hidden;
  height: auto;
  &:hover {
    cursor: pointer;
    transform: ${(props) => (props.isClicking ? 'scale(0.98)' : 'scale(1.04)')};
  }
`;

const ItemCover = styled(Image)`
  border-radius: ${(props) => props.theme.radius.lg.value} ${gridUnit};
  border: 1px solid #504f4e;
  overflow: visible;
  position: relative;
  transition: 0.2s;
  opacity: ${({ state }) => (state === 'entering' ? 0 : 1)};
`;

const ItemHoverContainer = styled.div`
  position: absolute;
  z-index: 10;
  top: 0;
  left: 0;
  right: 0;
  padding: 0px;
  margin: 0px;
  height: auto;
  &:hover {
    border: 0.8px solid ${(props) => props.theme.alias.image.border.value};
    border-radius: ${(props) => props.theme.radius.lg.value} ${gridUnit};
  }
`;

const ItemHoverImage = styled(Image)`
  border-radius: 15px; //15px not 16px: hack to avoid a "phantom line" at the bottom of image
  transition: 0.4s;
  display: ${({ state }) => (state === 'exited' ? 'none' : 'block')};
  opacity: ${({ state }) => (state === 'entered' ? 1 : 0)};
`;

const IconContainer = styled.div`
  position: absolute;
  left: 41.84%;
  right: 41.13%;
  top: 42.58%;
  bottom: 42.11%;
`;

const DetailsContainer = styled(Paragraph)`
  padding-top: ${({ state }) =>
    state === 'entered'
      ? (props) => props.theme.spacing[1].value + gridUnit
      : 0};
  transition: 0.4s;
  opacity: ${({ state }) => (state === 'entered' ? 1 : 0)};
  height: ${({ state }) => (state === 'entered' ? 1 : 0)};
  display: ${({ state }) => (state === 'exited' ? 'none' : 'block')};
`;

(1) 你必须组织你的代码

导入顺序：

反应+钩子
包
样式表
组件

页面底部的样式化组件

(2) 在网上查看 destructuring props

带有 useEffect 演示的鼠标事件监听器： Stacblitz

Answer 2

基于@MB_ 逻辑，我在 useEffect 中添加了 setIsLoaded(false) 并且有效:)

useEffect(() => {

    const currentMouseRef = mouseRef.current;
    
    if (currentMouseRef) {
      currentMouseRef.addEventListener('mouseover', handleMouseOver);
      currentMouseRef.addEventListener('mouseout', handleMouseOut);
      currentMouseRef.addEventListener('mousedown', handleMouseDown);
      currentMouseRef.addEventListener('mouseup', handleMouseUp);

      return () => {
        currentMouseRef.removeEventListener('mouseover', handleMouseOver);
        currentMouseRef.removeEventListener('mouseout', handleMouseOut);
        currentMouseRef.removeEventListener('mousedown', handleMouseDown);
        currentMouseRef.removeEventListener('mouseup', handleMouseUp);
        setIsLoaded(false); //Added this here
      };
    }
  }, []);

反应："Can't perform a React state update on an unmounted component" 没有 useEffect 函数

React: "Can't perform a React state update on an unmounted component" without useEffect function

javascript

reactjs

memory-leaks

next.js

styled-components

更新