New: First implementation

index.js

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+'use strict';
+
+var EventEmitter = require('events').EventEmitter;
+
+var namespace = '__sparklesEventEmitter';
+
+var ee = new EventEmitter();
+
+ee.setMaxListeners(0);
+
+function attach(type, listener){
+  // node will never fire the newListener on itself,
+  // so only check for remove/detach combo
+  if(type === 'removeListener' && listener === detach){
+    return;
+  }
+
+  if(!global[namespace]){
+    global[namespace] = ee;
+  }
+}
+
+function detach(){
+  var events = Object.keys(ee._events);
+  var removeListeners = ee.listeners('removeListener');
+  var newListeners = ee.listeners('newListener');
+
+  if(events.length > 2){
+    return;
+  }
+
+  if(removeListeners.length !== 1){
+    return;
+  }
+
+  if(newListeners.length !== 1 && events.length !== 1){
+    return;
+  }
+
+  delete global[namespace];
+
+  process.nextTick(rewire);
+}
+
+function rewire(){
+  var removeListeners = ee.listeners('removeListener');
+  var newListeners = ee.listeners('newListener');
+
+  if(!removeListeners.length){
+    ee.on('removeListener', detach);
+  }
+
+  if(!newListeners.length){
+    ee.on('newListener', attach);
+  }
+}
+
+rewire();
+
+module.exports = ee;

package.json

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+{
+  "name": "sparkles",
+  "version": "1.0.0",
+  "description": "Namespaced global event emitter",
+  "main": "index.js",
+  "scripts": {
+    "test": "lab -cv"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/phated/sparkles"
+  },
+  "keywords": [
+    "global",
+    "ee",
+    "events",
+    "emitter",
+    "namespaced"
+  ],
+  "author": "Blaine Bublitz <blaine@iceddev.com> (http://iceddev.com/)",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/phated/sparkles/issues"
+  },
+  "homepage": "https://github.com/phated/sparkles",
+  "dependencies": {
+    "code": "^1.2.1",
+    "lab": "^5.1.0"
+  }
+}

test/index.js

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+'use strict';
+
+var lab = exports.lab = require('lab').script();
+var describe = lab.describe;
+var it = lab.it;
+var before = lab.before;
+var beforeEach = lab.beforeEach;
+var after = lab.after;
+var afterEach = lab.afterEach;
+var expect = require('code').expect;
+
+var sparkles = require('../');
+
+function noop(){}
+
+function noop2(){}
+
+describe('sparkles', function(){
+
+  it('will attach an event emitter to global upon the first `on` call', function(done){
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    sparkles.on('test', noop);
+    expect(global.__sparklesEventEmitter).to.exist();
+    done();
+  });
+
+  it('removes the event emitter from global if no more listeners exist it', function(done){
+    expect(global.__sparklesEventEmitter).to.exist();
+    sparkles.removeListener('test', noop);
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    done();
+  });
+
+  it('even works with removeAllListeners', function(done){
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    sparkles.on('test1', noop);
+    sparkles.on('test2', noop2);
+    expect(global.__sparklesEventEmitter).to.exist();
+    sparkles.removeAllListeners();
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    done();
+  });
+
+  it('gracefully handles newListeners being added', function(done){
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    sparkles.on('newListener', noop);
+    expect(global.__sparklesEventEmitter).to.exist();
+    sparkles.removeAllListeners('newListener');
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    done();
+  });
+
+  it('gracefully handles removeListeners being added', function(done){
+    expect(global.__sparklesEventEmitter).to.not.exist();
+    sparkles.on('removeListener', noop);
+    sparkles.on('removeListener', noop2);
+    expect(global.__sparklesEventEmitter).to.exist();
+    sparkles.removeListener('removeListener', noop);
+    expect(global.__sparklesEventEmitter).to.exist();
+    done();
+  });
+
+  it('recovers from removeAllListeners on removeListener', function(done){
+    sparkles.removeAllListeners('removeListener');
+    process.nextTick(function(){
+      expect(sparkles.listeners('removeListener')).to.have.length(1);
+      done();
+    });
+  });
+});