0

这里只是一个例子，在浏览器中使用 websocket。将 Nodejs 与用于 Websocket 的 ws 库一起使用时也发生了同样的情况。

如果你把所有的东西都写在一个类之外，所有的处理程序都会被调用：EG：

try {
    var host = "ws://localhost:8080";
    var socket = new WebSocket(host); 

    socket.onopen = function(){ 
         // Do something
    } 
    socket.onmessage = function(msg){ // all stuff here will be called upon receiving message
         // Do something
    } 
    socket.onclose = function(){ 
         // Do something
    }            
} catch(exception){ 
     // Do something
}

但是，如果您想在一个类中实例化，则不会调用任何处理程序

var ws = new webSocketModule();

var webSocketModule = function(){
    try {
        var host = "ws://localhost:8080";
        this.socket = new WebSocket(host); 

        this.socket.onopen = function(){ 
             // Do something
        } 
        this.socket.onmessage = function(msg){ // None of these are called upon receiving message, however the server side will have connection message that means the websocket object is functioning just fine.
             // Do something
        } 
        this.socket.onclose = function(){ 
             // Do something
        }            
    } catch(exception){ 
         // Do something
    } 
}

那么，是不是我必须以凌乱的方式将所有东西都放在全球范围内？

添加到问题

var ws = new webSocketModule();

var webSocketModule = function(){
    try {
        var host = "ws://localhost:8080";
        this.socket = new WebSocket(host); 

        this.socket.onopen = function(){ 
             // Do something
        } 
        this.socket.onmessage = function(msg){
             // Do something
        } 
        this.socket.onclose = function(){ 
             // Do something
        }            
    } catch(exception){ 
         // Do something
    } 
}

ws.socket.onmessage = function(msg){
    // This will be called, kinda confusing
}

==================================================== =============== 补充：

var ws = new webSocketModule();  //Explain: This is the instance in the main file

// Down below is in eg: webSocketModule.js
var webSocketModule = function(){
    try {
        var host = "ws://localhost:8080";
        var skt = this.socket = new WebSocket(host); 

        skt.onopen = function(){ 
             // Do something
        } 
        skt.onmessage = function(msg){
             // Using a local variable for socket will not make this respond
             // Another side will successfully show connected and send the message
             // (At least it successfully printed the console log after the socket.send)
             // You have to register it like the above block "ws.socket.onmessage = ..." in the main file to make it respond
             // But this and the object should be the same point of reference right?
             // Seems Javascript handles it differently than JAVA or C++, is there any book that recommended that talks about how browser or NodeJS handles it? thanks.
             // Do something
        } 
        skt.onclose = function(){ 
             // Do something
        }            
    } catch(exception){ 
         // Do something
    } 
}
4

1 回答 1

0

你在实例化你的 webSocketModule 吗？

var webSocketModule = function() { ... }

var instance = new webSocketModule();

因为你赋值webSocketModule给了一个变量，所以必须先赋值才能使用它。如果您使用命名函数，那么没关系

于 2014-08-19T07:27:30.483 回答