如何滚动到底部的反应?

我想建立一个聊天系统，并自动滚动到底部时，进入窗口，当新的消息进来。如何在React中自动滚动到容器底部?

当前回答

这是你在TypeScript中解决这个问题的方法(使用你滚动到的目标元素的ref):

class Chat extends Component <TextChatPropsType, TextChatStateType> {
  private scrollTarget = React.createRef<HTMLDivElement>();
  componentDidMount() {
    this.scrollToBottom();//scroll to bottom on mount
  }

  componentDidUpdate() {
    this.scrollToBottom();//scroll to bottom when new message was added
  }

  scrollToBottom = () => {
    const node: HTMLDivElement | null = this.scrollTarget.current; //get the element via ref

    if (node) { //current ref can be null, so we have to check
        node.scrollIntoView({behavior: 'smooth'}); //scroll to the targeted element
    }
  };

  render <div>
    {message.map((m: Message) => <ChatMessage key={`chat--${m.id}`} message={m}/>}
     <div ref={this.scrollTarget} data-explanation="This is where we scroll to"></div>
   </div>
}

有关React和Typescript中使用ref的更多信息，你可以在这里找到一篇很棒的文章。

2020-05-18 13:27:07

其他回答

感谢@enlitement

我们应该避免使用findDOMNode，我们可以使用引用来跟踪组件

render() {
  ...

  return (
    <div>
      <div
        className="MessageList"
        ref={(div) => {
          this.messageList = div;
        }}
      >
        { messageListContent }
      </div>
    </div>
  );
}



scrollToBottom() {
  const scrollHeight = this.messageList.scrollHeight;
  const height = this.messageList.clientHeight;
  const maxScrollTop = scrollHeight - height;
  this.messageList.scrollTop = maxScrollTop > 0 ? maxScrollTop : 0;
}

componentDidUpdate() {
  this.scrollToBottom();
}

参考:

https://facebook.github.io/react/docs/react-dom.html#finddomnode https://www.pubnub.com/blog/2016-06-28-reactjs-chat-app-infinite-scroll-history-using-redux/

2017-01-23 14:50:38

在上面的答案中，scrollIntoView(…)方法有两个主要问题:

it's semantically incorrect, as it causes the entire page to scroll if your parent element is scrolled outside the window boundaries. The browser literally scrolls anything it needs to in getting the element visible. in a functional component using useEffect(), you get unreliable results, at least in Chrome 96.0.4665.45. useEffect() gets called too soon on page reload and the scroll doesn't happen. Delaying scrollIntoView with setTimeout(..., 0) fixes it for page reload, but not first load in a fresh tab, at least for me. shrugs

这是我一直在使用的解决方案，它很可靠，而且更兼容旧的浏览器:

function Chat() {
   const chatParent = useRef<HTMLDivElement(null);

   useEffect(() => {
      const domNode = chatParent.current;
      if (domNode) {
         domNode.scrollTop = domNode.scrollHeight;
      }
   })
   return (
      <div ref={chatParent}>
         ...
      </div>
   )
}

2021-11-23 20:55:32

我推荐的最简单和最好的方法是。

我的ReactJS版本:16.12.0

对于类组件

render()函数内的HTML结构

    render()
        return(
            <body>
                <div ref="messageList">
                    <div>Message 1</div>
                    <div>Message 2</div>
                    <div>Message 3</div>
                </div>
            </body>
        )
    )

scrollToBottom()函数，该函数将获取元素的引用。并根据scrollIntoView()函数滚动。

  scrollToBottom = () => {
    const { messageList } = this.refs;
    messageList.scrollIntoView({behavior: "smooth", block: "end", inline: "nearest"});
  }

并在componentDidMount()和componentDidUpdate()中调用上述函数

对于功能组件(挂钩)

导入useRef()和useEffect()

import { useEffect, useRef } from 'react'

在导出函数中，(与调用useState()相同)

const messageRef = useRef();

让我们假设页面加载时你必须滚动，

useEffect(() => {
    if (messageRef.current) {
      messageRef.current.scrollIntoView(
        {
          behavior: 'smooth',
          block: 'end',
          inline: 'nearest'
        })
    }
  })

或者，如果你想让它在执行动作时触发，

useEffect(() => {
  if (messageRef.current) {
    messageRef.current.scrollIntoView(
      {
        behavior: 'smooth',
        block: 'end',
        inline: 'nearest'
      })
  }
},
[stateVariable])

最后是HTML结构

return(
    <body>
        <div ref={messageRef}> // <= The only different is we are calling a variable here
            <div>Message 1</div>
            <div>Message 2</div>
            <div>Message 3</div>
        </div>
    </body>
)

有关Element.scrollIntoView()的更多解释，请访问developer.mozilla.org

更详细的解释在回调参考访问reactjs.org

2020-02-29 22:31:41

正如Tushar提到的，你可以在聊天的底部保留一个虚拟div:

render () {
  return (
    <div>
      <div className="MessageContainer" >
        <div className="MessagesList">
          {this.renderMessages()}
        </div>
        <div style={{ float:"left", clear: "both" }}
             ref={(el) => { this.messagesEnd = el; }}>
        </div>
      </div>
    </div>
  );
}

然后当你的组件更新时(即随着新消息的添加而更新状态)滚动到它:

scrollToBottom = () => {
  this.messagesEnd.scrollIntoView({ behavior: "smooth" });
}

componentDidMount() {
  this.scrollToBottom();
}

componentDidUpdate() {
  this.scrollToBottom();
}

我使用的是标准元素。scrollIntoView方法。

2017-01-17 15:20:28

另一个值得考虑的选择是react scroll组件。

2017-04-05 14:08:23

如何滚动到底部的反应?

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