Presence API for PubNub JavaScript SDK

Presence enables you to track the online and offline status of users and devices in real time, as well as 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

Learn more about our Presence feature here.

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 add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

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 V4 SDK:

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

Parameter	Type	Required	Default	Description
Operation Arguments	Hash	Yes		A hash of arguments.
`channels`	array	Optional		Specifies the `channel` name to return occupancy results. If `channel` is not provided, `hereNow()` will return data for all `channels`.
`channelGroups`	array	Optional		The `channel group` for which here now information should be received.
`includeUUIDs`	boolean	Optional	`true`	Setting `uuid` to `false` disables the return of uuids.
`includeState`	boolean	Optional	`false`	Setting state to `true` enables the return of subscriber state information.

Basic Usage

Get a list of UUIDs subscribed to channel:

try {
    const result = await pubnub.hereNow({
        channels: ["ch1"],
        channelGroups: ["cg1"],
        includeUUIDs: true,
        includeState: true,
    });
} catch (status) {
    console.log(status);
}

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:

try {
    const result = await pubnub.hereNow({
        channels: ["my_channel"],
        includeState: true,
    });
} catch (status) {
    console.log(status);
}

Example Response:

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

// Example of Response
{
    "totalChannels": 1,
    "totalOccupancy": 3,
    "channels": {
        "my_channel": {
            "occupants": [
                {
                    "uuid": "User 1"
                },
                {
                    "state": {
                        "age": 18
                    },
                    "uuid": "User 2"
                },
                {
                    "state": {
                        "age": 24
                    },
                    "uuid": "User 3"
                }
            ],
            "name": "my_channel",
            "occupancy": 3
        }
    }
}

Return Occupancy Only:

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

try {
    const result = await pubnub.hereNow({
        channels: ["my_channel"],
        includeUUIDs: false,
    });
} catch (status) {
    console.log(status);
}

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",
            "occupancy": 3
        }
    }
}

Channel Group Usage :

try {
    const result = await pubnub.hereNow({
        channelGroups: ["my_channel_group"],
    });
} catch (status) {
    console.log(status);
}

Example Response:

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

// Example of Response
{
    "totalChannels": 2,
    "totalOccupancy": 3,
    "channels": {
        "my_channel_1": {
            "occupants": [
                {
                    "state": null,
                    "uuid": "User1"
                },
                {
                    "state": null,
                    "uuid": "User3"
                }
            ],
            "name": "my_channel_1",
            "occupancy": 2
        },
        "my_channel_2": {
            "occupants": [
                {
                    "state": null,
                    "uuid": "User2"
                }
            ],
            "name": "my_channel_2",
            "occupancy": 1
        }
    }
}

Basic usage with Promises Requires Presence add-onRequires that the Presence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-
```
pubnub.hereNow({
    channels: ["ch1"],
    channelGroups : ["cg1"],
    includeUUIDs: true,
    includeState: true
}).then((response) => {
    console.log(response)
}).catch((error) => {
    console.log(error)
});
```

Where Now

Description

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.

Note

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 V4 SDK:

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

Parameter	Type	Required	Default	Description
Operation Arguments	Hash	Yes		A hash of arguments.
`uuid`	string	Optional	`current uuid`	Specifies the `uuid` to return channel list for.

Basic Usage

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:

try {
    const result = await pubnub.whereNow({
        uuid: "uuid",
    });
} catch (status) {
    console.log(status);
}

Response

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

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

Other Examples

Basic usage with Promises

pubnub.whereNow({
    uuid: "uuid"
}).then((response) => {
    console.log(response);
}).catch((error) => {
    console.log(error);
});

User State

Description

The state API is used to set/get key/value pairs specific to a subscriber uuid.

State information is supplied as a JSON object of key/value pairs.

Method(s)

Set State :

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

Parameter	Type	Required	Description
Operation Arguments	Hash	Yes	A hash of arguments.
`channels`	Array	Optional	Either `channels` or `channelGroups` should be provided, Specifies the `channels` to set the state.
`channelGroups`	Array	Optional	Either `channels` or `channelGroups` should be provided, Specifies the Channel Group to set the state
`state`	any	Optional	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>;

Parameter	Type	Required	Default	Description
Operation Arguments	Hash	Yes		A hash of arguments.
`uuid`	String	Optional	`current uuid`	The subscriber `uuid` to get the current state.
`channels`	Array	Optional		Either `channels` or `channelGroups` should be provided, Specifies the `channels` to get the state.
`channelGroups`	Array	Optional		Either `channels` or `channelGroups` should be provided, Specifies the Channel Group to get the state.

Basic Usage

Set State :

try {
    const result = await pubnub.setState({
        state: newState,
        channels: ["ch1"],
        channelGroups: ["cg1"],
    });
} catch (status) {
    console.log(status);
}

Get State :

try {
    const result = await pubnub.getState({
        uuid: "uuid",
        channels: ["ch1"],
        channelGroups: ["cg1"],
    });
} catch (status) {
    console.log(status);
}

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'
        }
    }
}

Other Examples

Set State Basic usage with Promises

pubnub.setState({
    state: newState,
    channels: ['ch1'],
    channelGroups: ['cg1']
}).then((response) => {
    console.log(response)
}).catch((error) => {
    console.log(error)
});

Get State Basic usage with Promises

pubnub.getState({
    uuid: "uuid",
    channels: ['ch1'],
    channelGroups: ['cg1']
}).then((response) => {
    console.log(response)
}).catch((error) => {
    console.log(error)
});