Question

我通常在python中编程，我正在尝试通常在python中运行的东西。我在课堂上有一个功能。它是mqtt库的回调函数。我想要的是将我收到的消息（在函数onMessageArrived中）保存到名为（this。）buffer的类变量中。

class sub{
    constructor(hostname,port,clientid,topic){
        this.buffer = [];
        this.hostname=hostname;
        this.port=port;
        this.clientid = clientid;
        this.topic = topic;
        this.client = new Paho.MQTT.Client(hostname,port, clientid);
        // set callback handlers
        this.client.onConnectionLost = this.onConnectionLost;
        this.client.onMessageArrived = this.onMessageArrived; <----Problem
        // connect the client
        this.client.connect({onSuccess:this.onConnect});

                                      }
    onConnect(){
          console.log('OnConnect');
    }

    onConnectionLost(responseObject) {
          if (responseObject.errorCode !== 0) {
            console.log("onConnectionLost:"+responseObject.errorMessage);
        }
        }

    onMessageArrived(message) {
          console.log("onMessageArrived:"+message.payloadString);
          this.buffer.push(message.payloadString)   <-------------Problem

    }


    subs(){
        this.client.subscribe(this.topic)
    }
    publ(message){
        var mg = new Paho.MQTT.Message(message);
        mg.destinationName = this.topic;
        this.client.send(mg);
    }

    }

问题是onMessageArrived函数不会将消息推送到this.buffer变量中 - 看起来函数不知道它的内部类，因此我无法通过＆＃39;这来访问类变量。＆＃39;。在python中它以这种方式工作。我非常绝望，因为我看起来像是这个功能被完全隔离，除了打印信息之外别无他法。

the error: 
onConnectionLost:AMQJS0005E Internal error. Error Message: Cannot read 
property 'push' of undefined, Stack trace: TypeError: Cannot read property 
'push' of undefined

提前致谢

Javascript - 无法将类的函数返回到类的变量中

0 个答案: