Presence API for JavaScript SDK

Presence enables you to track the online and offline status of users and devices in real-time and store custom state information. Presence provides authoritative information on:

• When a user has joined or left a channel
• Who, and how many, users are subscribed to a particular channel
• Which channel(s) an individual user is subscribed to
• Associated state information for these users

To learn more about Presence as a feature, visit Presence Overview.

Supported and recommended asynchronous patterns

PubNub supports Callbacks, Promises, and Async/Await for asynchronous JS operations. The recommended pattern is Async/Await and all sample requests in this document are based on it. This pattern returns a status only on detecting an error. To receive the error status, you must add the try...catch syntax to your code.

Here now

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

You can obtain information about the current state of a channel including a list of unique user-ids currently subscribed to the channel and the total occupancy count of the channel by calling the hereNow() function in your application.

Cache

This method has a 3 second response cache time.

Method(s)

To call Here Now, you can use the following method(s) in the JavaScript SDK:

pubnub.hereNow({
    channels: Array<string> ,
    channelGroups: Array<string> ,
    includeUUIDs: boolean ,
    includeState: boolean 
}); Promise<HereNowResponse>

* required

Parameter	Description
channels Type: array<string> Default: n/a	Specifies the channel name to return occupancy results. You must specify either channels or channelGroups.
channelGroups Type: array<string> Default: n/a	The channel group for which here now information should be received. You must specify either channels or channelGroups.
includeUUIDs Type: boolean Default: true	Setting uuid to false disables the return of uuids.
includeState Type: boolean Default: false	Setting state to true enables the return of subscriber state information.

Sample code

Reference code

This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document.

Get a list of UUIDs subscribed to channel

Response

type hereNowResponse = {
    totalChannels: number, // totalChannels = get total of channels
    totalOccupancy: number, // totalOccupancy = get total of occupancies
    channels: object // channels = get a map with values for each channel with uuids and states for each occupant of the channel
}

Other examples

Returning state

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

Example response

// Example of Status
{
    "error": false,
    "operation": "PNHereNowOperation",
    "statusCode": 200
}

// Example of Response
{
    "totalChannels": 1,
    "totalOccupancy": 3,
    "channels": {
        "my_channel": {
            "occupants": [
                {

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Return occupancy only

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

You can return only the occupancy information for a single channel by specifying the channel and setting UUIDs to false:

Example response

// Example of Status
{
    "error": false,
    "operation": "PNHereNowOperation",
    "statusCode": 200
}

// Example of Response
{
    "totalChannels": 1,
    "totalOccupancy": 3,
    "channels": {
        "my_channel": {
            "occupants": [],
            "name": "my_channel",

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Channel group usage

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

Example response

// Example of Status
{
    "error": false,
    "operation": "PNHereNowOperation",
    "statusCode": 200
}

// Example of Response
{
    "totalChannels": 2,
    "totalOccupancy": 3,
    "channels": {
        "my_channel_1": {
            "occupants": [
                {

show all 38 lines

Sample code with promises

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

Where now

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

You can obtain information about the current list of channels to which a UUID is subscribed to by calling the whereNow function in your application.

Timeout events

If the app is killed/crashes and restarted (or the page containing the PubNub instance is refreshed on the browser) within the heartbeat window no timeout event is generated.

Method(s)

To call whereNow, you can use the following method(s) in the JavaScript SDK:

pubnub.whereNow({
    uuid: string
}): Promise<WhereNowResponse>

* required

Parameter	Description
uuid Type: string Default: current uuid	Specifies the uuid to return channel list for.

Sample code

You simply need to define the uuid to be used to send the data to as in the example below.

Get a list of channels a UUID is subscribed to

Response

// Example of Status
{
    error: false,
    operation: "PNWhereNowOperation",
    statusCode: 200
}

// Example of Response
{
    "channels": ["ch1", "ch2"]
}

User state

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

Clients can set a dynamic custom state (score, game state, location) for their users on one or more channels and store it on a channel as long as the user stays subscribed.

The state is not persisted, and when the client disconnects, the state data is lost. For more information, refer to Presence State.

Method(s)

Set state

pubnub.setState({
    channels: Array<string> ,
    channelGroups: Array<string> ,
    state: any
}): Promise<SetStateResponse>;

* required

Parameter	Description
channels Type: Array	Either channels or channelGroups should be provided, Specifies the channels to set the state.
channelGroups Type: Array	Either channels or channelGroups should be provided, Specifies the Channel Group to set the state
state Type: any	JSON object of key/value pairs with supported data-types of int, float and string. Nesting of key/values is not permitted and key names beginning with prefix pn are reserved. If the state parameter is undefined, the current state for the specified uuid will be returned. If a specified key already exists for the uuid it will be over-written with the new value. Key values can be deleted by setting the particular value to null.

Get state

pubnub.getState({
    uuid: string,
    channels: Array<string>, 
    channelGroups: Array<string>
}): Promise<GetStateResponse>; 

* required

Parameter	Description
uuid Type: String Default: current uuid	The subscriber uuid to get the current state.
channels Type: Array Default: n/a	Either channels or channelGroups should be provided, Specifies the channels to get the state.
channelGroups Type: Array Default: n/a	Either channels or channelGroups should be provided, Specifies the Channel Group to get the state.

Sample code

Set state

Get state

Response

Set state

// Example of Status
{
    error: false,
    operation: "PNSetStateOperation",
    statusCode: 200
}

// Example of Response
{
    state: {
        me: 'typing'
    }
}

Get state

// Example of Status
{
    error: false,
    operation: "PNGetStateOperation",
    statusCode: 200
}

// Example of Response
{
    channels: {
        ch1: {
            me: 'typing'
        }
    }
}