JavaScript变量作用域

Question

下面的代码将创建一个新的new客户端套接字连接。我遇到的问题是如何获得socket对象的作用域。

如何在init()函数中引用套接字对象？

在下面的示例中，当在init()函数中执行this.socket时，它看起来像是在创建一个位于init函数本地的新的socket对象。

    return webClient = {
        clientConnection: null,
        ioClient: null,
        socket: null,
        ready: false,
        init: function(callback){
            this.ioClient = require('socket.io-client');
            console.log('Web Config :');
            console.log(webClientConfig);
            this.socket = this.ioClient.connect(webClientConfig.connectionString, {'forceNew':true });
            this.socket.on('connect', function(){
                console.log('Web Client Connected');
        });
    };

Answer 1

在此上下文中，该标识符指的是te webClient。

Answer 2

全局声明一个变量以获取websocket连接，如下所示

var webSocket = require('socket.io-client');

然后你可以在任何地方使用webSocket变量。喜欢

return webClient = {
        clientConnection: null,
        ioClient: null,
        socket: null,
        ready: false,
        init: function(callback){
            this.ioClient = webSocket;
            console.log('Web Config :');
            console.log(webClientConfig);
            this.socket = this.ioClient.connect(webClientConfig.connectionString, {'forceNew':true });
            this.socket.on('connect', function(){
                console.log('Web Client Connected');
        });
    };

Answer 3

如果您期望(并且没有看到) this作为webClient.init中的webClient -您可以简单地这样做

var webClient = {
    clientConnection: null,
    ioClient: null,
    socket: null,
    ready: false,
    init: function(callback){
        webClient.ioClient = require('socket.io-client');
        console.log('Web Config :');
        console.log(webClientConfig);
        webClient.socket = this.ioClient.connect(webClientConfig.connectionString, {'forceNew':true });
        webClient.socket.on('connect', function(){
            console.log('Web Client Connected');
    });
};
return webClient;

不过，我会把require('socket.io-client');作为一个全局

const ioClient = require('socket.io-client');
//
// 
//
var webClient = {
    clientConnection: null,
    ioClient: null,
    socket: null,
    ready: false,
    init: function(callback){
        webClient.ioClient = ioClient;
        console.log('Web Config :');
        console.log(webClientConfig);
        webClient.socket = this.ioClient.connect(webClientConfig.connectionString, {'forceNew':true });
        webClient.socket.on('connect', function(){
            console.log('Web Client Connected');
    });
};
return webClient;