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

完整版(Typescript):

import * as React from React 导出类DivWithScrollHere扩展React。组件<any, any> { loading:any = React.createRef(); componentDidMount () { this.loading.scrollIntoView(假); } 呈现(){ 回报( <div ref={e =>{这个。装载= e;}}> <LoadingTile /> </div> . txt ) } }

其他回答

完整版(Typescript):

import * as React from React 导出类DivWithScrollHere扩展React。组件<any, any> { loading:any = React.createRef(); componentDidMount () { this.loading.scrollIntoView(假); } 呈现(){ 回报( <div ref={e =>{这个。装载= e;}}> <LoadingTile /> </div> . txt ) } }

您可以使用引用来跟踪组件。

如果你知道如何设置单个组件的引用(最后一个),请发布!

以下是我发现对我有用的方法:

class ChatContainer extends React.Component {
  render() {
    const {
      messages
    } = this.props;

    var messageBubbles = messages.map((message, idx) => (
      <MessageBubble
        key={message.id}
        message={message.body}
        ref={(ref) => this['_div' + idx] = ref}
      />
    ));

    return (
      <div>
        {messageBubbles}
      </div>
    );
  }

  componentDidMount() {
    this.handleResize();

    // Scroll to the bottom on initialization
    var len = this.props.messages.length - 1;
    const node = ReactDOM.findDOMNode(this['_div' + len]);
    if (node) {
      node.scrollIntoView();
    }
  }

  componentDidUpdate() {
    // Scroll as new elements come along
    var len = this.props.messages.length - 1;
    const node = ReactDOM.findDOMNode(this['_div' + len]);
    if (node) {
      node.scrollIntoView();
    }
  }
}

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>
   )
}

另一个值得考虑的选择是react scroll组件。

工作的例子:

您可以使用DOM scrollIntoView方法使组件在视图中可见。

为此,在呈现组件时,只需使用ref属性为DOM元素提供一个引用ID。然后在componentDidMount生命周期上使用scrollIntoView方法。我只是把这个解决方案的工作示例代码。以下是每次接收到消息时的组件呈现。您应该编写代码/方法来呈现该组件。

class ChatMessage extends Component {
    scrollToBottom = (ref) => {
        this.refs[ref].scrollIntoView({ behavior: "smooth" });
    }

    componentDidMount() {
        this.scrollToBottom(this.props.message.MessageId);
    }

    render() {
        return(
            <div ref={this.props.message.MessageId}>
                <div>Message content here...</div>
            </div>
        );
    }
}

这里this.props.message.MessageId是作为道具传递的特定聊天消息的唯一ID