Presence API for PubNub 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 add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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>
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| Operation Arguments | Hash | Yes | A hash of arguments. | |
channels | array<string> | Optional | Specifies the channel name to return occupancy results. You must specify either channels or channelGroups. | |
channelGroups | array<string> | Optional | The channel group for which here now information should be received. You must specify either channels or channelGroups. | |
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
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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": [
{
Return Occupancy Only
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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",
Channel Group Usage
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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": [
{
Basic usage with Promises
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.hereNow({
channels: ["ch1"],
channelGroups : ["cg1"],
includeUUIDs: true,
includeState: true
}).then((response) => {
console.log(response)
}).catch((error) => {
console.log(error)
});
Where Now
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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>
| 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
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
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)
});