在ReactJS中添加onChange后无法在输入字段中键入

Question

我正在创建一个ReactJS聊天应用程序。 如果用户开始输入消息，那么我希望另一个用户应该收到一条消息，提示正在输入用户名 。 因此，为此，我使用了onChange，但是用户输入的内容都不会出现在输入文本框中。

Message.js文件

const socket = io('localhost:9000');

class Message extends Component {
  constructor(props) {
    super(props);
    this.state = {
      data: "",
      messages: "",
      typing: "",
    }
    this.sendMessage = this.sendMessage.bind(this);
    this.onTyping = this.onTyping.bind(this);
  }

  sendMessage(message) {
    console.log(this.state.data, "=============>state dataa")
    const data = {
      message,
      senderId: this.props.userId,
      roomId: this.state.data.roomId
    };
    console.log('Inside New message', data);
    socket.emit('new message', data );
  }

  onTyping(typing) {
    console.log(this.state.typing, "=====Typing Message====");
  }

  render() {
    const { messages, userId, chatDetails } = this.props;
    console.log('Chat in container : ', messages.toJS());

    return (
      <div className="message">
        { !chatDetails && <h1 style={{ textAlign: 'center' }}>Initiate a New Chat.</h1> }
        { chatDetails && <MessageList messages={this.state.message} user={userId} /> }
        { chatDetails && <MessageBar send={this.sendMessage} typingMessage={this.onTyping}/> }
      </div>
    );
  }
}

const mapStateToProps = state => ({
  messages: state.get('messages'),
  userId: state.getIn(['profile', 'id']),
  chatDetails: state.getIn(['videocall', 'callerDetails'])
});

const mapDispatchToProps = dispatch => ({
  saveMessage: payload => dispatch(saveMessage(payload)),
});

export default connect(mapStateToProps, mapDispatchToProps)(Message);

MessageBar.js

class MessageBar extends Component {
  constructor(props) {
    super(props);
    this.state = { message: '' };
    this.sendMessage = this.sendMessage.bind(this);
    this.onTyping = this.onTyping.bind(this);
  }

  onTyping(e) {
    this.setState({typing: e.target.value});
    this.props.typingMessage(this.state.typing);
  }

  sendMessage(e) {
    this.setState({message: ''});
    this.props.send(this.state.message);
  }


  render() {
    return (
      <div className="message-bar">
        <input
          value={this.state.message}
          type="text"
          onChange={this.onTyping}
          placeholder="Type your message ..."
        />
        <button onClick={this.sendMessage}>
          <i className="fa fa-paper-plane" />
        </button>
      </div>
    );
  }
}

export default MessageBar;

我正在为该聊天应用程序使用socket.io和reactjs。有人可以帮我吗？

Answer 1

我认为您必须更新消息的状态，而不是在onTyping函数中进行键入 。

onTyping(e) {
 this.setState({message: e.target.value});
 this.props.typingMessage(this.state.typing);
}

Answer 2

setState是异步的，因此您需要等待状态设置后才能将其发送到prop。

class MessageBar extends Component {
  constructor(props) {
    super(props);
    this.state = { message: '' };
    this.sendMessage = this.sendMessage.bind(this);
    this.onTyping = this.onTyping.bind(this);
  }

  onTyping(e) {
    // here wait for state to set
    this.setState({typing: e.target.value}, () => {
        this.props.typingMessage(this.state.typing);
    });
  }

  sendMessage(e) {
    this.setState({message: ''});
    this.props.send(this.state.message);
  }


  render() {
    return (
      <div className="message-bar">
        <input
          value={this.state.message}
          type="text"
          onChange={this.onTyping}
          placeholder="Type your message ..."
        />
        <button onClick={this.sendMessage}>
          <i className="fa fa-paper-plane" />
        </button>
      </div>
    );
  }
}

export default MessageBar;