Socket IO - how do I get a list of connected sockets clients

Question

I m trying to get a list of all the sockets clients that are currently connected    io sockets does not return an array  unfortunately    I know I could keep my own list using an array  but don t think this is an optimal solution for 2 reasons    Redundancy  Socket IO already keeps a copy of this list  Socket IO provides method to set arbitrary field values for clients  i e  socket set  nickname    superman    so I d need to keep up with these changes if I were to maintain my own list    Help

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on socket io 1 3 i ve accomplished this in 2 lines  var usersSocketIds   Object keys chat adapter rooms  room name     var usersAttending     map usersSocketIds  function socketClientId   return chat connected socketClientId

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This is the best way to access it in socket io 1 3  Object keys socket adapter rooms room id

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Using Socket IO 1 x   Get array of the connected clients   io engine     io eio      gt  true Object keys io engine clients       gt     US8AxrUrrDF G7ZUAAAA    Ov2Ca24Olkhf2NHbAAAB    Object keys io eio clients          gt     US8AxrUrrDF G7ZUAAAA    Ov2Ca24Olkhf2NHbAAAB      Get the number of connected clients   io engine clientsCount      gt  2 io eio clientsCount         gt  2

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For version 2 3 this works and it will get you the socket too  it seems to me that socketIo is changing too fast and to much with to little readable documentation after using it for a while    ioSite of      in roomId  clients  error  clients    gt        if  error  throw error      for  var i 0 i lt clients length i              clientId clients i           console log clientId               load the socket of your namespace         var socket ioSite of      in roomId  connected clientId          console log socket constructor name           console log socket id               still this does not feel right  as I have always this feeling with socket Io somehow

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I think we can access the socket object from the server  and you can assign the nickname  and point its socket id   io sockets on  connection  function socket        io sockets sockets  nickname     socket id      client on  chat   function data                  var sock id   io sockets sockets  nickname           io sockets sockets sock id  emit  private    message                      On disconnect please remove the nickname from io sockets sockets

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I see a lot of good answers here and many where quite useful but not quite what I needed  I am using sockets for a pubsub feature in which an interested client can listen to any changes in a given record   My specific issue was that the same socket was joining the same room several times  The solution to this was to check if the socket had the room inside its rooms property already   var room   myObj id toString    if  socket rooms indexOf room      -1        socket join room       socket emit  subscribed    to   room      else       console log  Already in room        Hope this helps someone

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After socket io 1 0 we cannot use   io sockets clients     or io sockets clients  room       anymore  Instead you can use the following   var clients in the room   io sockets adapter rooms roomId    for  var clientId in clients in the room       console log  client   s   clientId     Seeing is believing    var client socket   io sockets connected clientId    Do whatever you want with this

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Version  2 0 In version  2 0 you specify the namespace room node you are querying against  As with broadcasting  the default is all clients from the default namespace        const io   require  socket io        io clients  error  clients    gt          if  error  throw error        console log clients        gt   6em3d4TJP8Et9EMNAAAA  G5p55dHhGgUnLUctAAAB       Gets a list of client IDs connected to specific namespace  across all nodes if applicable   const io   require  socket io      io of   chat   clients  error  clients    gt         if  error  throw error       console log clients        gt   PZDoMHjiu8PYfRiKAAAF  Anw2LatarvGVVXEIAAAD       An example to get all clients in namespace s room  const io   require  socket io      io of   chat   in  general   clients  error  clients    gt          if  error  throw error        console log clients        gt   Anw2LatarvGVVXEIAAAD        This is from the official documentation  Socket IO Server-API

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As of version 1 5 1  I m able to access all the sockets in a namespace with   var socket ids   Object keys io of   namespace   sockets   socket ids forEach function socket id        var socket   io of   namespace   sockets socket id       if  socket connected               Do something                For some reason  they re using a plain object instead of an array to store the socket IDs

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Socket io 1 4  Object keys io sockets sockets   gives you all the connected sockets   Socket io 1 0 As of socket io 1 0  the actual accepted answer isn t valid anymore  So I made a small function that I use as a temporary fix    function findClientsSocket roomId  namespace        var res             the default namespace is           ns   io of namespace              if  ns            for  var id in ns connected                if roomId                    var index   ns connected id  rooms indexOf roomId                   if index     -1                        res push ns connected id                                    else                   res push ns connected id                                      return res      Api for No namespace becomes      var clients   io sockets clients       becomes    var clients   findClientsSocket        var clients   io sockets clients  room       all users from room  room     becomes var clients   findClientsSocket  room      Api for a namespace becomes       var clients   io of   chat   clients       becomes var clients   findClientsSocket null    chat        var clients   io of   chat   clients  room       all users from room  room     becomes var clients   findClientsSocket  room     chat      Also see this related question  in which I give a function that returns the sockets for a given room   function findClientsSocketByRoomId roomId    var res        room   io sockets adapter rooms roomId   if  room        for  var id in room        res push io sockets adapter nsp connected id            return res      Socket io 0 7  API for no namespace   var clients   io sockets clients    var clients   io sockets clients  room       all users from room  room    For a namespace  var clients   io of   chat   clients    var clients   io of   chat   clients  room       all users from room  room    Note  Since it seems the socket io API is prone to breaking  and some solution rely on implementation details  it could be a matter of tracking the clients yourself   var clients        io sockets on  connect   function client        clients push client         client on  disconnect   function             clients splice clients indexOf client   1

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I ve gone through this pain today  Socket io will be much better if they could make a proper documentation for their API   Anyway  I tried to look into io sockets and found a number of options we can use   io sockets connected   Return  socket 1 id      socket 2 id        This is the most convenient one  since you can just refer to io sockets connected id  then do common things like emit   io sockets sockets   Returns   socket 1    socket 2          Can refer to socket i id to distinguish io sockets adapter sids   Return  socket 1 id      socket 2 id        Looks similar to the first one but the object is not actually the socket  just the information      Not directly helps but still relevant io sockets adapter rooms   Returns  room 1 id      room 2 id      io sockets server eio clients   Return client sockets io sockets server eio clientsCount   Return number of connected clients   Also  do note that when using socket io with namespace  the above methods will break since io sockets becomes an array instead of an object  To resolve  just replace io sockets by io  i e io sockets connected becomes io connected  io sockets adapter rooms becomes io adapter rooms       Tested on socket io 1 3 5

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Socket io 1 4 4  Sample code for you   function get clients by room roomId  namespace            io of namespace         in roomId  clients function  error  clients                if  error    throw error                console log clients 0         gt   Anw2LatarvGVVXEIAAAD              console log io sockets sockets clients 0       socket detail             return clients                      I think will help someone this code block

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For cluster mode  using redis-adaptor   io in  lt room gt   clients function err  clients           As each socket is itself a room  so one can find whether a socket exist using the same

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If the project has a socket io cluster this means socket io-redis adapter is being used   If the case like the above  getting the all connected sockets id process must be applied via socket io-redis adapter  The examples below might be used for this   io of      adapter clients function  err  clients      console log  clients     clients      an array containing all connected socket ids       io of      adapter allRooms function  err  rooms      console log  all rooms     rooms         Please visit socket io-redis github page for more details

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v 10  var clients   io nsps      adapter rooms  vse         clients  will return something like  Room   sockets     3kiMNO8xwKMOtj3zAAAC   true  FUgvilj2VoJWB196AAAD  true    length  2      var count   clients length      2 var sockets   clients map  item   gt       all sockets room  vse         return io sockets sockets item             sample  gt  gt  gt  var handshake    sockets i  handshake   handshake address   time  issued     etc

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socket io 1 7 3  I used Object Keys to get the array of socket connected  Then in the same array iterate with map function to build a new array of objects   var connectedUsers   Object keys io sockets connected  map function socketId        return   socket id   socketId  socket username  io sockets connected socketId  username            test console log connectedUsers     Perhaps this answer can help to get socket id username array

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socket io 3 0  io in  room1   sockets sockets forEach  socket key   gt           console log socket           all socket instance in room1

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In Socket IO 1 4   To get the array of All connected Users    var allConnectedClients   Object keys io sockets connected     This will return the array of SockeId of all the connected clients   To get the Count of all clients    var clientsCount   io engine clientsCount      This will return the count of connected clients

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In Socket IO 0 7 you have a clients method on the namespaces  this returns a array of all connected sockets   API for no namespace   var clients   io sockets clients    var clients   io sockets clients  room       all users from room  room    For a namespace  var clients   io of   chat   clients    var clients   io of   chat   clients  room       all users from room  room    Hopes this helps someone in the future     NOTE  This Solution ONLY works with version prior to 1 0     UPDATED 2020 Mar 06  From 1 x and above  please refer to this link  getting how many people are in a chat room in socket io

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This is the simplest way in Socket IO 1 0   if you are not using namespaces or rooms   io nsps      sockets length   This looks at the default namespace and determines the length of the sockets array  without needing to use Object keys

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I believe you can access this from the socket s manager property   var handshaken   io manager handshaken  var connected   io manager connected  var open   io manager open  var closed   io manager closed

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Socket io 1 7 3       function getConnectedList          let list               for   let client in io sockets connected                 list push client                 return list    console log  getConnectedList         returns    yIfhb2tw7mxgrnF6AAAA    qABFaNDSYknCysbgAAAB

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Here is a quick way to convert the hash of connected sockets from a namespace into an array using ES6 generators  applies to socket io    v1 0 0    io on  connection   function socket      var hash   io of      connected   var list   null    hash Symbol iterator    function             for  of loop to invoke Object keys   default iterator        to get the array values instead of the keys     for var id of Object keys hash   yield hash id         list       hash    console log Array isArray list      true

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As of socket io 1 5  note the change from indexOf which appears to de depreciated  and replaced by valueOf  function findClientsSocket roomId  namespace        var res           var ns   io of namespace               the default namespace is          if  ns            for  var id in ns connected                if  roomId                      var index   ns connected id  rooms indexOf roomId                    var index   ns connected id  rooms valueOf roomId      Problem was here                  if index     -1                        res push ns connected id                                    else                   res push ns connected id                                      return res length      For socket io version 2 0 3  the following code works   function findClientsSocket io  roomId  namespace        var res               ns   io of namespace               the default namespace is          if  ns            for  var id in ns connected                if roomId                       ns connected id  rooms is an object                  var rooms   Object values ns connected id  rooms                     var index   rooms indexOf roomId                   if index     -1                        res push ns connected id                                                else                   res push ns connected id                                      return res

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For anyone that just wants a COUNT of the connected clients I believe this will do it   io sockets manager server connections

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Very simple in socket io 1 3   io sockets sockets - is an array containing the connected socket objects  If you stored the username in each socket  you can do   io sockets sockets map function e        return e username       Boom  You have the names of all connected users

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I don t know if this is still going  But something like this is what I ended up using  I keep a session object on each connected socket  which in turn contains the username and other info   var connectedUsers   Object keys io sockets connected  map function socketId        return io sockets connected socketId  session username

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