Question

我是编程的初学者，我正在尝试javascript类，我想从覆盖函数 onConnMessage 中调用 boardCastinit 函数，但是我收到此错误消息，请帮助解决这个问题。

boReferenceError：boardCastInit未定义

websocket.js

class websocket extends webSocketModel {

constructor() {
    let server = new Server();
    let mongodb = new mongoDB();
    super(server.server);
}




onConnMessage(message) {

    let clients = this.clients;
    boardCastInit(1);
}


 boardCastInit(data){
       console.log(data)
   }


}

module.exports = websocket;

websocketModel.js

const ws = require('websocket').server;

class webSocketModel {

constructor(httpServer) {
    if(!httpServer) throw 'Null Http Server';
    this.websocket = new ws({ httpServer: httpServer, autoAcceptConnections: false });
    this.websocket.on('request', this.onConnOpen.bind(this));
}


onConnOpen(request) {
    var connection = request.accept('echo-protocol', request.origin);
    console.log('Connection Accepted');

    connection.on('message', this.onConnMessage);
    connection.on('close', this.onConnClose);
}

onConnMessage(message) {
    if (message.type === 'utf8') {
        console.log(message.utf8Data);
    } else if (message.type == 'binary') {
        console.log(message.binaryData.length + 'bytes');
    }
}

onConnClose(reasonCode, description) {
    console.log('Connection Closed');
}
}

module.exports = webSocketModel;

Answer 1

只需将boardCastInit(1)更改为this.boardCastInit(1)

即可

onConnMessage(message) {

    let clients = this.clients;
    this.boardCastInit(1);
}

Answer 2

您应该从课程this引用中调用它：

class websocket extends webSocketModel {

   constructor() {
      let server = new Server();
      let mongodb = new mongoDB();
      super(server.server);
   }

   onConnMessage(message) {
      let clients = this.clients;
      this.boardCastInit(1);
   }


   boardCastInit(data){
      console.log(data)
   }

}

module.exports = websocket;

Answer 3

你错过了这个（应该是this.boardCastInit（1））。

Answer 4

这可能是一个具有约束力的问题。也许您想在onConnMessage方法上使用箭头功能：

onConnMessage = (message) => {
    let clients = this.clients;
    this.boardCastInit(1);
}

这将确保this引用定义了websocket方法的boardCastInit类。

Answer 5

尝试在构造函数中绑定boardCastInit()函数，如下所示。

constructor() {
    let server = new Server();
    let mongodb = new mongoDB();
    super(server.server);
    this.boardCastInit = this.boardCastInit.bind(this);
}

然后从this引用中调用它。

onConnMessage(message) {
    let clients = this.clients;
    this.boardCastInit(1);
}

javascript类调用函数

5 个答案: