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
我在消息的末尾创建了一个空元素,并滚动到该元素。不需要跟踪裁判。
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/
我在消息的末尾创建了一个空元素,并滚动到该元素。不需要跟踪裁判。
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>
)
}
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 ) } }
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。
推荐文章
- 如何配置历史记录?
- React钩子:从回调中访问最新状态
- React-Native:应用程序未注册错误
- ReactJS和公共文件夹中的图像
- React: 'Redirect'没有从' React -router-dom'中导出
- 如何在React中使用钩子强制组件重新渲染?
- React组件中使用TypeScript的默认属性值
- 反应钩子-正确的方式清除超时和间隔
- 在React.js中正确的img路径
- 在React.js中更新组件onScroll的样式
- onClick ReactJS调用多个函数
- 为什么React 16中的Fragments比容器div更好?
- 如何在ReactJS中验证嵌套对象的PropTypes ?
- 如何在ReactJS中从“外部”访问组件方法?
- 'React'指的是一个UMD全局,但当前文件是一个模块