title: Socket.io events triggering multiple times on Angular.js view change
body: <p>Warning: I am pretty new to coding and web development.</p>
  
  <p>I am making an angular application that uses socket.io to communicate realtime events on a node (express) server to other clients. The problem I am having is that when I am in the application and switch routes from "/pb" to "/" then back again, the "init" socket event is being fired twice on the client side. From what I can tell, the client is emitting the "requestInit" event only once, and the server is responding by emitting the "init" event only once. However, the client is running the code in the socketio.on('init') function multiple times when I switch views.</p>
  
  <p>For example: I will open the application and navigate to /pb, the console will log</p>
  
  <pre><code>connected to socket
  recieved socket event from server: Init
  initCount: 1 
  </code></pre>
  
  <p>Now when I navigate to "/" then back to "/pb", the console will log</p>
  
  <pre><code>recieved socket event from server: Init
  initCount: 2
  recieved socket event from server: Init
  initCount: 1
  </code></pre>
  
  <p>For each time I switch views, the initCount gets higher, so if I switch back and forth 5 times, the initCount will log 5 times, starting at 5 and ending with 1.</p>
  
  <p>So the socketio.on('init') function on the client side is being fired multiple times when I enter the view, and in backwards order. My original guess is that is has something to do with the socket not closing when I switch views, so when I come back, it receives an "init" event for each open socket. However, the socketio.on('connect') function only fires on the initial navigation to "/pb". I've been googling for hours and I am still not able to find out whats going on. Any help would be appreciated. Here is the cod that is giving me trouble.</p>
  
  <p>Client:</p>
  
  <pre><code>var app = angular.module('MainApp', ['ngRoute']);
  
  app.config(['$routeProvider', '$locationProvider', function ($routeProvider, $locationProvider){
  
      $routeProvider
          .when('/', {
              templateUrl: 'views/home.html',
              controller: 'HomeController',
              activeTab: 'home'
          })
          .when('/pb', {
              templateUrl: 'views/pb.html',
              controller: 'PbController',
              activeTab: 'pb'
          })
          .otherwise({
              redirectTo: '/'
          });
  
      $locationProvider.html5Mode(true);
  }]);
  
  // SocketIO factory
  app.factory('socketio', ['$rootScope', function($rootScope){
      var socket = io.connect('http://localhost:3000');
      return {
          on: function(eventName, callback){
              socket.on(eventName, function() {
                  var args = arguments;
                  $rootScope.$apply(function(){
                      callback.apply(socket, args);
                  });
              });
          },
          emit: function(eventName, data, callback){
              socket.emit(eventName, data, function() {
                  var args = arguments;
                  $rootScope.$apply(function(){
                      if(callback){
                          callback.apply(socket, args);
                      }
                  });
              });
          }
      };
  }]);
  
  app.controller('PbController', ['$scope', 'socketio', function ($scope, socketio){
  
       $scope.initCount = 0;
  /*
      ~~~~~~~~~~ Socket events ~~~~~~~~~~~~~~~~
  */
      socketio.emit('requestInit');
  
      socketio.on('connect', function(){
          console.log('connected to socket');
      });
  
      socketio.on('init', function (){
          console.log("recieved socket event from server: Init");
          $scope.initCount += 1;
          console.log("init count: " + $scope.initCount);
      });
  }]);
  </code></pre>
  
  <p>Server:</p>
  
  <pre><code>var pbServerController = function (io){
  
  io.on('connection', function (socket){
      console.log("Client connected, new socket issued: "+socket.id);
  
      socket.on('requestInit', function(){
          console.log("sending Init socketio event");
          socket.emit('init');
      });
  };
  
  module.exports = pbServerController;
  </code></pre>