为什么不是'；这个EventEmitter pubsub singleton接口是否在node.js中工作？

我试图在node.js中分离发布者和订阅者，以便能够通过共享的EventEmitter实例作为总线相互发送数据

我的总线遵循[此处][1]讨论的单例方法

bus.js文件

// https://derickbailey.com/2016/03/09/creating-a-true-singleton-in-node-js-with-es6-symbols/
// create a unique, global symbol name
// -----------------------------------

const FOO_KEY = Symbol.for("test.exchanges.bus");
const EventEmitter = require("events");

// check if the global object has this symbol
// add it if it does not have the symbol, yet
// ------------------------------------------

var globalSymbols = Object.getOwnPropertySymbols(global);
var hasFoo = (globalSymbols.indexOf(FOO_KEY) > -1);

if (!hasFoo){
  global[FOO_KEY] = {
    foo: new EventEmitter()
  };
}

// define the singleton API
// ------------------------

var singleton = {};

Object.defineProperty(singleton, "instance", {
  get: function(){
    return global[FOO_KEY];
  }
});

// ensure the API is never changed
// -------------------------------

Object.freeze(singleton);

// export the singleton API only
// -----------------------------

module.exports = singleton;

const bus = require("./bus");

class Publisher {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);
        this.test();
    }

    test() {
        setInterval(() => {
            this.emitter.emit("test", Date.now());
        }, 1000);
    }

}

module.exports = Publisher;

console.log(bus.instance.foo);

const bus = require("./bus");

class Subscriber {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);

        this.emitter.on("test", this.handleTest);
    }

    handleTest(data) {
        console.log("handling test", data);
    }
}

module.exports = Subscriber;

console.log(bus.instance.foo);

我的理解是，当我在不同的模块中需要这个文件时，应该提供相同的foo对象。这不是单身的目的吗

pub.js文件

// https://derickbailey.com/2016/03/09/creating-a-true-singleton-in-node-js-with-es6-symbols/
// create a unique, global symbol name
// -----------------------------------

const FOO_KEY = Symbol.for("test.exchanges.bus");
const EventEmitter = require("events");

// check if the global object has this symbol
// add it if it does not have the symbol, yet
// ------------------------------------------

var globalSymbols = Object.getOwnPropertySymbols(global);
var hasFoo = (globalSymbols.indexOf(FOO_KEY) > -1);

if (!hasFoo){
  global[FOO_KEY] = {
    foo: new EventEmitter()
  };
}

// define the singleton API
// ------------------------

var singleton = {};

Object.defineProperty(singleton, "instance", {
  get: function(){
    return global[FOO_KEY];
  }
});

// ensure the API is never changed
// -------------------------------

Object.freeze(singleton);

// export the singleton API only
// -----------------------------

module.exports = singleton;

const bus = require("./bus");

class Publisher {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);
        this.test();
    }

    test() {
        setInterval(() => {
            this.emitter.emit("test", Date.now());
        }, 1000);
    }

}

module.exports = Publisher;

console.log(bus.instance.foo);

const bus = require("./bus");

class Subscriber {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);

        this.emitter.on("test", this.handleTest);
    }

    handleTest(data) {
        console.log("handling test", data);
    }
}

module.exports = Subscriber;

console.log(bus.instance.foo);

sub.js文件

// https://derickbailey.com/2016/03/09/creating-a-true-singleton-in-node-js-with-es6-symbols/
// create a unique, global symbol name
// -----------------------------------

const FOO_KEY = Symbol.for("test.exchanges.bus");
const EventEmitter = require("events");

// check if the global object has this symbol
// add it if it does not have the symbol, yet
// ------------------------------------------

var globalSymbols = Object.getOwnPropertySymbols(global);
var hasFoo = (globalSymbols.indexOf(FOO_KEY) > -1);

if (!hasFoo){
  global[FOO_KEY] = {
    foo: new EventEmitter()
  };
}

// define the singleton API
// ------------------------

var singleton = {};

Object.defineProperty(singleton, "instance", {
  get: function(){
    return global[FOO_KEY];
  }
});

// ensure the API is never changed
// -------------------------------

Object.freeze(singleton);

// export the singleton API only
// -----------------------------

module.exports = singleton;

const bus = require("./bus");

class Publisher {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);
        this.test();
    }

    test() {
        setInterval(() => {
            this.emitter.emit("test", Date.now());
        }, 1000);
    }

}

module.exports = Publisher;

console.log(bus.instance.foo);

const bus = require("./bus");

class Subscriber {
    constructor(emitter) {
        this.emitter = emitter;
        console.log(this.emitter);

        this.emitter.on("test", this.handleTest);
    }

    handleTest(data) {
        console.log("handling test", data);
    }
}

module.exports = Subscriber;

console.log(bus.instance.foo);

---

当我在两个单独的终端窗口上运行pub.js和sub.js时，sub.js立即执行完毕，就好像publisher没有将消息推送到它一样。有谁能指出如何将发行商和订阅者分离到同一个事件总线上工作？

< P>你可以考虑重新设计你的总线模块。我建议将其创建为扩展

EventEmitter

的类，然后返回该类的实例化实例

现在，当第一次加载此文件时，将运行类代码，并实例化一个对象，然后将其导出回

require

将缓存此实例，下次加载此文件时，它将返回相同的对象。这使它成为一个单例，您现在可以将其用作公共总线

下面是一些代码来演示这一点：

bus.js bus.spec.js