Question

这里只是一个例子，在浏览器中使用websocket。将Nodejs与ws Library for Websocket一起使用时也是如此。

如果你把一切都写在一个类的旁边，那么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，如果要在类中实例化，则不会调用非处理程序

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
    } 
}

因此，我必须采用凌乱的方式将所有内容全局化吗？

添加问题

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
}

=============================================== ================== 添加了：

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
    } 
}

Answer 1

你是否在实例化你的webSocketModule？

var webSocketModule = function() { ... }

var instance = new webSocketModule();

因为您已将webSocketModule分配给变量，所以必须先将其分配才能使用它。如果您使用了named function，则无关紧要

在Javascript中使用Library的EventHandler和“this”修饰符

1 个答案: