react项目中聊天界面新增对话自动滚动到底部

class组件写法1

class Messages extends React.Component {

  const messagesEndRef = React.createRef()

  componentDidMount () {
    this.scrollToBottom()
  }
  componentDidUpdate () {
    this.scrollToBottom()
  }
  scrollToBottom = () => {
    this.messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
  }
  render () {
    const { messages } = this.props
    return (
      <div>
        {messages.map(message => <Message key={message.id} {...message} />)}
        <div ref={this.messagesEndRef} />
      </div>
    )
  }
}

class组件写法2

class Messages extends React.Component {
  scrollToBottom = () => {
    this.messagesEnd.scrollIntoView({ behavior: "smooth" });
  }

  componentDidMount() {
    this.scrollToBottom();
  }

  componentDidUpdate() {
    this.scrollToBottom();
  }

  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>
    );
  }
}

函数组件写法

import React, { useEffect, useRef } from 'react'

const Messages = ({ messages }) => {

  const messagesEndRef = useRef(null)

  const scrollToBottom = () => {
    messagesEndRef.current?.scrollIntoView({ behavior: "smooth" })
  }

  useEffect(() => {
    scrollToBottom()
  }, [messages]);

  return (
    <div>
      {messages.map(message => <Message key={message.id} {...message} />)}
      <div ref={messagesEndRef} />
    </div>
  )
}