npm install mqtt --save
------
yarn add mqtt

connection: {
  protocol: "ws",
  host: "broker.emqx.io",
  port: 8083,
  endpoint: "/mqtt",
  clean: true,
  connectTimeout: 30 * 1000, // ms
  reconnectPeriod: 4000, // ms
  clientId: "emqx_vue_" + Math.random().toString(16).substring(2, 8),
  // 隨機(jī)數(shù) 每次不能重復(fù)
  username: "emqx_test",
  password: "emqx_test",
},

import mqtt from "mqtt";
let client = {}
client = mqtt.connect(url, options)

client.on('connect', (e) => {
  // 訂閱主題
  
})

client.subscribe(topic, { qos: 1 }, (err) => {
  if (!err) {
    console.log('訂閱成功')
  } else {
    console.log('消息訂閱失??！')
  }
})

client.publish(publishTopic, `{"messageType":1,"messageContent":""}`, { qos: 0 }, (err) => {
  if (!err) {
    console.log('發(fā)送成功')
    client.subscribe(topic, { qos: 1 }, (err) => {
      if (!err) {
        console.log('訂閱成功')
      } else {
        console.log('消息訂閱失??！')
      }
    })
  } else {
    console.log('消息發(fā)送失?。?)
  }
})

client.unsubscribe(topicList, (error) => {
  console.log('主題為' + topicList + '取消訂閱成功', error)
})

export function unconnect() {
  client.end()
  client = null
  // Message.warning('服務(wù)器已斷開連接！')
  console.log('服務(wù)器已斷開連接！')
}

import type { IClientOptions, MqttClient } from 'mqtt';
import mqtt from 'mqtt';

interface ClientOptions extends IClientOptions {
  clientId: string;
}

interface SubscribeOptions {
  topic: string;
  callback: (topic: string, message: string) => void;
  subscribeOption?: mqtt.IClientSubscribeOptions;
}

interface PublishOptions {
  topic: string;
  message: string;
}

class Mqtt {
  private static instance: Mqtt;
  private client: MqttClient | undefined;
  private subscribeMembers: Record<string, ((topic: string, message: string) => void) | undefined> = {};
  private pendingSubscriptions: SubscribeOptions[] = [];
  private pendingPublications: PublishOptions[] = [];
  private isConnected: boolean = false;

  private constructor(url?: string) {
    if (url) {
      this.connect(url);
    }
  }

  public static getInstance(url?: string): Mqtt {
    if (!Mqtt.instance) {
      Mqtt.instance = new Mqtt(url);
    } else if (url && !Mqtt.instance.client) {
      Mqtt.instance.connect(url);
    }
    return Mqtt.instance;
  }

  private connect(url: string): void {
    console.log(url, clientOptions);
    if (!this.client) {
      this.client = mqtt.connect(url, clientOptions);
      this.client.on('connect', this.onConnect);
      this.client.on('reconnect', this.onReconnect);
      this.client.on('error', this.onError);
      this.client.on('message', this.onMessage);
    }
  }

  public disconnect(): void {
    if (this.client) {
      this.client.end();
      this.client = undefined;
      this.subscribeMembers = {};
      this.isConnected = false;
      console.log(`服務(wù)器已斷開連接！`);
    }
  }

  public subscribe({ topic, callback }: SubscribeOptions): void {
    if (this.isConnected) {
      this.client?.subscribe(topic, { qos: 1 }, error => {
        if (error) {
          console.log(`客戶端: ${clientOptions.clientId}, 訂閱主題: ${topic}失敗: `, error);
        } else {
          console.log(`客戶端: ${clientOptions.clientId}, 訂閱主題: ${topic}成功`);
        }
      });
      this.subscribeMembers[topic] = callback;
    } else {
      this.pendingSubscriptions.push({ topic, callback });
    }
  }

  public unsubscribe(topic: string): void {
    if (!this.client) {
      return;
    }
    this.client.unsubscribe(topic, error => {
      if (error) {
        console.log(`客戶端: ${clientOptions.clientId}, 取消訂閱主題: ${topic}失敗: `, error);
      } else {
        console.log(`客戶端: ${clientOptions.clientId}, 取消訂閱主題: ${topic}成功`);
      }
    });
    this.subscribeMembers[topic] = undefined;
  }

  public publish({ topic, message }: PublishOptions): void {
    if (this.isConnected) {
      this.client?.publish(topic, message, { qos: 1 }, e => {
        if (e) {
          console.log(`客戶端: ${clientOptions.clientId}, 發(fā)送主題為: ${topic} 的消息, 發(fā)送失敗: `, e);
        }
      });
    } else {
      this.pendingPublications.push({ topic, message });
    }
  }

  private onConnect = (e: any): void => {
    console.log(`客戶端: ${clientOptions.clientId}, 連接服務(wù)器成功:`, e);
    this.isConnected = true;
    this.processPendingSubscriptions();
    this.processPendingPublications();
  };

  private onReconnect = (): void => {
    console.log(`客戶端: ${clientOptions.clientId}, 正在重連:`);
    this.isConnected = false;
  };

  private onError = (error: Error): void => {
    console.log(`客戶端: ${clientOptions.clientId}, 連接失敗:`, error);
    this.isConnected = false;
  };

  private onMessage = (topic: string, message: Buffer): void => {
    // console.log(
    //   `客戶端: ${clientOptions.clientId}, 接收到來自主題: ${topic} 的消息: `,
    //   message.toString(),
    // );
    const callback = this.subscribeMembers?.[topic];
    callback?.(topic, message.toString());
  };

  private processPendingSubscriptions(): void {
    while (this.pendingSubscriptions.length > 0) {
      const { topic, callback, subscribeOption } = this.pendingSubscriptions.shift()!;
      this.subscribe({ topic, callback, subscribeOption });
    }
  }

  private processPendingPublications(): void {
    while (this.pendingPublications.length > 0) {
      const { topic, message } = this.pendingPublications.shift()!;
      this.publish({ topic, message });
    }
  }
}

const clientOptions: ClientOptions = {
  clean: true,
  connectTimeout: 500,
  protocolVersion: 5,
  rejectUnauthorized: false,
  username: 'admin',
  password: 'Anjian-emqx',
  clientId: `client-${Date.now()}`
};

// export default Mqtt.getInstance("ws://192.168.11.14:8083/mqtt");
// export default Mqtt.getInstance("ws://192.168.11.14:8083/mqtt");
// export default Mqtt.getInstance(JSON.parse(import.meta.env.VITE_OTHER_SERVICE_BASE_URL).mqtt);
const { protocol, host } = window.location;
export default Mqtt.getInstance(`${protocol.replace('http', 'ws')}//${host.replace('localhost', '127.0.0.1')}/mqtt/`);

.env.test
VITE_OTHER_SERVICE_BASE_URL= `{
  "mqtt": "ws://192.168.11.14:8083/mqtt"
}`