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.
Method(s)
To call Here Now
, you can use the following method(s) in the JavaScript V4 SDK:
hereNow({Array channels, Array channelGroups, Boolean includeUUIDs, Boolean includeState})
Parameter | Type | Required | Defaults | 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: 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-try { const result = await pubnub.hereNow({ channels: ["my_channel"], includeState: true, }); } catch (status) { console.log(status); }
// 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: 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-You can return only the
occupancy
information for a single channel by specifying the channel and settingUUIDs
to false:try { const result = await pubnub.hereNow({ channels: ["my_channel"], includeUUIDs: false, }); } catch (status) { console.log(status); }
// 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 : 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-try { const result = await pubnub.hereNow({ channelGroups: ["my_channel_group"], }); } catch (status) { console.log(status); }
// 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
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 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:
whereNow({String uuid})
Parameter | Type | Required | Defaults | 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
pubnub.whereNow({
uuid: "uuid"
}).then((response) => {
console.log(response);
}).catch((error) => {
console.log(error);
});
User State
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
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)
setState({Array channels, Array channelGroups, Object state})
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 | Object | 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 . |
getState({String uuid, Arraychannels, ArraychannelGroups})
Parameter | Type | Required | Defaults | 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
try {
const result = await pubnub.setState({
state: newState,
channels: ["ch1"],
channelGroups: ["cg1"],
});
} catch (status) {
console.log(status);
}
try {
const result = await pubnub.getState({
uuid: "uuid",
channels: ["ch1"],
channelGroups: ["cg1"],
});
} catch (status) {
console.log(status);
}
Response
// Example of Status
{
error: false,
operation: "PNSetStateOperation",
statusCode: 200
}
// Example of Response
{
state: {
me: 'typing'
}
}
// 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) });