Publish/Subscribe API for JavaScript SDK
PubNub delivers messages worldwide in less than 30 ms. Send a message to one recipient or broadcast to thousands of subscribers.
For higher-level conceptual details on publishing and subscribing, refer to Connection Management and to Publish Messages.
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 status errors, you must use the try...catch
syntax in your code.
Publish
publish()
sends a message to all channel subscribers. PubNub replicates the message across its points of presence and delivers it to all subscribed clients on that channel.
- Prerequisites and limitations
- Security
- Message data
- Size
- Publish rate
- Custom message type
- Best practices
- You must initialize PubNub with the
publishKey
. - You don't have to be subscribed to a channel to publish to it.
- You cannot publish to multiple channels simultaneously.
Secure messages with Transport Layer Security (TLS) or Secure Sockets Layer (SSL) by setting ssl
to true
during initialization. You can also encrypt messages.
The message can contain any JavaScript Object Notation (JSON)-serializable data (objects, arrays, integers, strings). Avoid special classes or functions. Strings can include any UTF‑8 characters.
Don't JSON serialize
You should not JSON serialize the message
and meta
parameters when sending signals, messages, or files as the serialization is automatic. Pass the full object as the message/meta payload and let PubNub handle everything.
The maximum message size is 32 KiB. This includes the escaped character count and the channel name. Aim for under 1,800 bytes for optimal performance.
If your message exceeds the limit, you'll receive a Message Too Large
error. To learn more or calculate payload size, see Message size limits.
You can publish as fast as bandwidth allows. There is a soft throughput limit because messages may drop if subscribers can't keep up.
For example, publishing 200 messages at once may cause the first 100 to drop if a subscriber hasn't received any yet. The in-memory queue stores only 100 messages.
You can optionally provide the customMessageType
parameter to add your business-specific label or category to the message, for example text
, action
, or poll
.
- Publish to a channel serially (not concurrently).
- Verify a success return code (for example,
[1,"Sent","136074940..."]
). - Publish the next message only after a success return code.
- On failure (
[0,"blah","<timetoken>"]
), retry. - Keep the in-memory queue under 100 messages to avoid drops.
- Throttle bursts to meet latency needs (for example, no more than 5 messages per second).
Method(s)
To Publish a message
, you can use the following method(s) in the JavaScript SDK:
pubnub.publish({
message: any,
channel: string,
meta: any,
storeInHistory: boolean,
sendByPost: boolean,
ttl: number,
customMessageType: string
}): Promise<PublishResponse>;
Parameter | Description |
---|---|
message *Type: any Default: n/a | The message may be any valid JSON type including objects, arrays, strings, and numbers. |
channel *Type: string Default: n/a | Specifies the channel ID to publish messages to. |
storeInHistory Type: boolean Default: true | If true the messages are stored in history. If storeInHistory is not specified, then the history configuration on the key is used. |
sendByPost Type: boolean Default: false | When true , the SDK uses HTTP POST to publish the messages. The message is sent in the BODY of the request, instead of the query string when HTTP GET is used. Also the messages are compressed thus reducing the size of the messages. Using HTTP POST to publish messages adheres to RESTful API best practices. |
meta Type: any Default: n/a | Publish extra meta with the request. |
ttl Type: number Default: n/a | Set a per message time to live in Message Persistence.
|
customMessageType Type: string Default: n/a | A case-sensitive, alphanumeric string from 3 to 50 characters describing the business-specific label or category of the message. Dashes - and underscores _ are allowed. The value cannot start with special characters or the string pn_ or pn- . Examples: text , action , poll . |
Sample code
Reference code
Publish a message to a channel
Subscribe to the channel
Before running the above publish example, either using the Debug Console or in a separate script running in a separate terminal window, subscribe to the same channel that is being published to.
Response
type PublishResponse = {
timetoken: number
}
Other examples
Publish a JSON-serialized message
Store the published message for 10 hours
Publish successful
Publish unsuccessful by network down
Publish unsuccessful by initialization without a publish key
Fire
The fire endpoint sends a message to Functions event handlers and Illuminate. The message goes directly to handlers registered on the target channel and triggers their execution. The handler can read the request body. Messages sent via fire()
aren't replicated to subscribers and aren't stored in history.
Method(s)
To Fire a message
, you can use the following method(s) in the JavaScript SDK:
fire({
Object message,
String channel,
Boolean sendByPost,
Object meta
})
Parameter | Description |
---|---|
message *Type: Object Default: n/a | The message may be any valid JSON type including objects, arrays, strings, and numbers. |
channel *Type: String Default: n/a | Specifies channel ID to publish messages to. |
sendByPost Type: Boolean Default: false | If true the messages sent via POST. |
meta Type: Object Default: n/a | Publish extra meta with the request. |
Sample code
Fire a message to a channel
Signal
The signal()
function sends a signal to all subscribers of a channel.
By default, signals are limited to a message payload size of 64
bytes. This limit applies only to the payload, and not to the URI or headers. If you require a larger payload size, please contact support.
Method(s)
To Signal a message
, you can use the following method(s) in the JavaScript SDK:
pubnub.signal({
message: string,
channel: string,
customMessageType: string,
}): Promise<SignalResponse>;
Parameter | Description |
---|---|
message *Type: string | The message may be any valid JSON type including objects, arrays, strings, and numbers. |
channel *Type: string | Specifies channel ID to send messages to. |
customMessageType Type: string | A case-sensitive, alphanumeric string from 3 to 50 characters describing the business-specific label or category of the message. Dashes - and underscores _ are allowed. The value cannot start with special characters or the string pn_ or pn- . Examples: text , action , poll . |
Sample code
Signal a message to a channel
Response
type SignalResponse = {
timetoken: number
}
Subscribe
The subscribe function creates an open TCP socket to PubNub and begins listening for messages and events on a specified entity or set of entities. To subscribe successfully, configure the appropriate subscribeKey
at initialization.
Conceptual overview
For more general information about subscriptions, refer to Subscriptions.
Entities are first-class citizens that provide access to their encapsulated APIs. You can subscribe using the PubNub client object or directly on a specific entity:
A newly subscribed client receives messages after the subscribe()
call completes. You can configure retryConfiguration
to automatically attempt to reconnect and retrieve any available messages if a client gets disconnected.
Subscribe only opens the connection
Calling subscribe()
opens a connection but doesn't deliver messages to your code. You must also add event listeners to receive messages and access sender information. The message object received through listeners includes the sender's ID in the publisher
field.
Subscription scope
Subscriptions let you attach listeners for specific real-time update types. Your app receives messages and events through those listeners. There are two types:
subscription
: created from an entity and scoped to that entity (for example, a particular channel)subscriptionSet
: created from the PubNub client and scoped to the client (for example, all subscriptions created on a singlepubnub
object). A set can include one or more subscriptions.
The event listener is a single point through which your app receives all the messages, signals, and events in the entities you subscribed to. For information on adding event listeners, refer to Event listeners.
Add subscriptions to an existing set
If you subscribe to a subscription set and then add more subscriptions to it, they are automatically subscribed to.
Create a subscription
An entity-level subscription
allows you to receive messages and events for only that entity for which it was created. Using multiple entity-level subscription
s is useful for handling various message/event types differently in each channel.
// entity-based, local-scoped
const channel = pubnub.channel('channel_1');
channel.subscription(subscriptionOptions)
Parameter | Description |
---|---|
subscriptionOptions Type: subscriptionOptions | Subscription behavior configuration. |
Create a subscription set
A client-level subscriptionSet
allows you to receive messages and events for all entities in the set. A single subscriptionSet
is useful for similarly handling various message/event types in each channel.
// client-based, general-scoped
pubnub.subscriptionSet({
channels: string[],
channelGroups: string[],
subscriptionOptions: subscriptionOptions
}))
Parameter | Description |
---|---|
→ channels Type: string[] | Channels to subscribe to. Either channels or channelGroups is mandatory. |
→ channelGroups Type: string[] | Channel groups to subscribe to. Either channels or channelGroups is mandatory. |
→ subscriptionOptions Type: subscriptionOptions | Subscription behavior configuration. |
subscriptionOptions
subscriptionOptions
is a class. Available properties include:
Option | Type | Description |
---|---|---|
receivePresenceEvents | boolean | Whether presence updates for userId s should be delivered through the listener streams. For information on how to receive presence events and what those events are, refer to Presence Events. |
cursor | object | Cursor from which to return any available cached messages. Message retrieval with cursor is not guaranteed and should only be considered a best-effort service. A cursor consists of a timetoken and region: cursor?: { timetoken?: string; region?: number } If you pass any primitive type, the SDK converts them into SubscriptionCursor but if their value is not a 17-digit number or a string with numeric characters, the provided value will be ignored. |
Modify a subscription set
You can add and remove subscriptions to and from an existing set to create new sets. If you subscribe to a subscription set and then add more subscriptions to it, they are automatically subscribed to.
Refer to the Other examples section for more information on adding and removing subscriptions.
Method(s)
subscription
and subscriptionSet
use the same subscribe()
method.
Subscribe
To subscribe, you can use the following method in the JavaScript SDK:
subscription.subscribe()
subscriptionSet.subscribe()
Sample code
Wildcard subscribe and message objects
Wildcard subscribe (e.g., sports.*
) works the same as regular subscribe - you still need to add event listeners to receive messages. The message objects received include the sender's ID in the publisher
field, the actual channel name in the channel
field, and the wildcard match in the subscription
field.
Other examples
Create a subscription set from 2 individual subscriptions
Create a subscription set from 2 sets
Add subscriptions to an existing set
Returns
The subscribe()
method doesn't have a return value.
Entities
Entities are subscribable objects for which you can receive real-time updates (messages, events, etc).
Create channels
This method returns a local channel
entity.
pubnub.channel(string)
Parameter | Description |
---|---|
channel *Type: string | The ID of the channel to create a subscription of. |
Sample code
Create channel groups
This method returns a local channelGroup
entity.
pubnub.channelGroup(string)
Parameter | Description |
---|---|
channel_group *Type: string | The name of the channel group to create a subscription of. |
Sample code
Create channel metadata
This method returns a local channelMetadata
entity.
pubnub.channelMetadata(string)
Parameter | Description |
---|---|
channelMetadata *Type: string | The String identifier of the channel metadata object to create a subscription of. |
Sample code
Create user metadata
This method returns a local userMetadata
entity.
pubnub.userMetadata(string)
Parameter | Description |
---|---|
userMetadata *Type: string | The String identifier of the user metadata object to create a subscription of. |
Sample code
Event listeners
Messages and events are received in your app using a listener. This listener allows a single point to receive all messages, signals, and events.
You can attach listeners to the instances of subscription
, subscriptionSet
, and, in the case of the connection status, the PubNub client.
Add listeners
You can implement multiple listeners with the addListener()
method or register an event-specific listener that receives only a selected type, like message
or file
.
Method(s)
Sample code
Message object contains sender information
When you receive messages through listeners, the message object includes the sender's ID in the publisher
field, along with the message content, channel name, timetoken, and other metadata.
Add connection status listener
The PubNub client has a listener dedicated to handling connection status updates.
Client scope
This listener is only available on the PubNub object.
Method(s)
Sample code
Returns
The subscription status. For information about available statuses, refer to SDK statuses.
Unsubscribe
Stop receiving real-time updates from a subscription
or a subscriptionSet
.
Method(s)
subscription.unsubscribe()
subscriptionSet.unsubscribe()
Sample code
Returns
None
Unsubscribe all
Stop receiving real-time updates from all data streams and remove the entities associated with them.
Client scope
This method is only available on the PubNub object.
Method(s)
pubnub.unsubscribeAll()
Sample code
Returns
None
Subscribe (old)
Not recommended
The use of this method is discouraged. Use Subscribe instead.
Receive messages
Your app receives messages and events via event listeners. The event listener is a single point through which your app receives all the messages, signals, and events that are sent in any channel you are subscribed to.
For more information about adding a listener, refer to the Event Listeners section.
Description
This function causes the client to create an open TCP socket to the PubNub Real-Time Network and begin listening for messages on a specified channel
. To subscribe to a channel
ID the client must send the appropriate subscribeKey
at initialization.
By default a newly subscribed client will only receive messages published to the channel after the subscribe()
call completes.
Connectivity notification
You can be notified of connectivity via the listener, on establishing connection the statusEvent.category
returns PNConnectedCategory
.
By waiting for the connect event to return before attempting to publish, you can avoid a potential race condition on clients that subscribe and immediately publish messages before the subscribe
has completed.
Unsubscribing from all channels
Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken
and thus, there could be some gaps in the subscription that may lead to message loss.
Method(s)
To Subscribe to a channel
, you can use the following method(s) in the JavaScript SDK:
pubnub.subscribe({
channels: Array<string>,
channelGroups: Array<string>,
withPresence: boolean,
timetoken: number
}): Promise<SubscribeResponse>;
Parameter | Description |
---|---|
channels *Type: Array <string> Default: n/a | Specifies the channels to subscribe to. It is possible to specify multiple channels as a list or as an array. |
channelGroups Type: Array <string> Default: n/a | Specifies the channelGroups to subscribe to. |
withPresence Type: boolean Default: false | If true it also subscribes to presence instances. |
timetoken Type: number Default: n/a | Specifies timetoken from which to start returning any available cached messages. Message retrieval with timetoken is not guaranteed and should only be considered a best-effort service. |
Sample code
Subscribe to a channel:
Event listeners
The response of the call is handled by adding a Listener. Please see the Event Listeners section for more details. Listeners should be added before calling the method.
Returns
The following objects will be returned in the status response
Object | Description |
---|---|
category | PNConnectedCategory |
operation | PNSubscribeOperation |
affectedChannels | The channels affected in the operation, of type array. |
subscribedChannels | All the current subscribed channels, of type array. |
affectedChannelGroups | The channel groups affected in the operation, of type array. |
lastTimetoken | The last timetoken used in the subscribe request, of type long. |
currentTimetoken | The current timetoken fetched in the subscribe response, which is going to be used in the next request, of type long. |
{
category: 'PNConnectedCategory',
operation: 'PNSubscribeOperation',
affectedChannels: ['my_channel_1'],
subscribedChannels: ['my_channel_1'],
affectedChannelGroups: [],
lastTimetoken: '14974492380756600',
currentTimetoken: '14974492384874375'
}
The following objects will be returned in the subscribe message response
Object | Description |
---|---|
channel | The channel ID for which the message belongs. |
subscription | The channel group or wildcard subscription match (if exists). |
timetoken | Publish timetoken . |
message | The payload . |
actualChannel | Deprecated. Use property channel . |
subscribedChannel | Deprecated. Use property subscription . |
{
actualChannel: null,
channel: "my_channel_1",
message: "Hello World!",
publisher: "pn-58e1a647-3e8a-4c7f-bfa4-e007ea4b2073",
subscribedChannel: "my_channel_1",
subscription: null,
timetoken: "14966804541029440"
}
The following objects will be returned in the Presence response
Object | Description |
---|---|
action | Can be join , leave , state-change or timeout . |
channel | The channel ID for which the message belongs. |
occupancy | No. of users connected with the channel ID. |
state | User State. |
subscription | The channel group or wildcard subscription match (if exists) |
timestamp | Current timetoken . |
timetoken | Publish timetoken . |
uuid | UUIDs of users who are connected with the channel ID. |
{
category: 'PNConnectedCategory',
operation: 'PNSubscribeOperation',
affectedChannels: ['my_channel_1'],
subscribedChannels: ['my_channel_1'],
affectedChannelGroups: [],
lastTimetoken: '14974492380756600',
currentTimetoken: '14974492384874375'
}
Other examples
Subscribing to multiple channels
It's possible to subscribe to more than one channel using the Multiplexing feature. The example shows how to do that using an array to specify the channel names.
Alternative subscription methods
You can also use Wildcard Subscribe and Channel Groups to subscribe to multiple channels at a time. To use these features, the Stream Controller add-on must be enabled on your keyset in the Admin Portal.
Subscribing to a Presence channel
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.
For any given channel there is an associated Presence channel. You can subscribe directly to the channel by appending -pnpres
to the channel name. For example the channel named my_channel
would have the presence channel named my_channel-pnpres
.
Wildcard subscribe to channels
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal (with Enable Wildcard Subscribe checked). Read the support page on enabling add-on features on your keys.
Wildcard subscribes allow the client to subscribe to multiple channels using wildcard. For example, if you subscribe to a.*
you will get all messages for a.b
, a.c
, a.x
. The wildcarded *
portion refers to any portion of the channel string name after the dot (.)
.
Wildcard grants and revokes
Only one level (a.*
) of wildcarding is supported. If you grant on *
or a.b.*
, the grant will treat *
or a.b.*
as a single channel named either *
or a.b.*
. You can also revoke permissions from multiple channels using wildcards but only if you previously granted permissions using the same wildcards. Wildcard revokes, similarly to grants, only work one level deep, like a.*
.
Subscribing with 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.
Required UUID
Always set the UUID
to uniquely identify the user or device that connects to PubNub. This UUID
should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the UUID
, you won't be able to connect to PubNub.
Subscribe to a channel group
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Subscribe to the presence channel of a channel group
Requires Stream Controller and Presence add-ons
This method requires that both the Stream Controller and Presence add-ons are enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Subscribing to multiple channel groups
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Subscribing to a channel and channel group simultaneously
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Sample Responses
Join event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "join",
"timetoken": "15119466699655811",
"occupancy": 2,
"uuid": "User1",
"timestamp": 1511946669
}
Leave event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "leave",
"timetoken": "15119446002445794",
"occupancy": 1,
"uuid": "User1",
"timestamp": 1511944600
}
Timeout event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "timeout",
"timetoken": "15119519897494311",
"occupancy": 3,
"uuid": "User2",
"timestamp": 1511951989
}
State change event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "state-change",
"state": {
"isTyping": true
},
"timetoken": "15119477895378127",
"occupancy": 5,
"uuid": "User4",
"timestamp": 1511947789
}
Interval event
{
"action": "interval",
"occupancy": 2,
"timestamp": 1511947739
}
When a channel is in interval mode with presence_deltas
pnconfig
flag enabled, the interval message may also include the following fields which contain an array of changed UUIDs since the last interval message.
- joined
- left
- timedout
For example, this interval message indicates there were 2 new UUIDs that joined and 1 timed out UUID since the last interval:
{
"action":"interval",
"timestamp":1548340678,
"occupancy":2,
"join":["pn-94bea6d1-2a9e-48d8-9758-f1b7162631ed","pn-cecbfbe3-312f-4928-93a2-5a79c91b10e0"]},
"timedout":["pn-cecbfbe3-312f-4928-93a2-5a79c91b10e0"],
"b":"my-channel-pnpres"
}
If the full interval message is greater than 30KB
(since the max publish payload is ∼32KB
), none of the extra fields will be present. Instead there will be a here_now_refresh
boolean field set to true
. This indicates to the user that they should do a hereNow
request to get the complete list of users present in the channel.
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "interval",
"timetoken": "15119477396210903",
"occupancy": 4,
"timestamp": 1511947739,
"here_now_refresh" : true
}
You can be notified of connectivity status, message, and presence notifications via the listeners.
Listeners should be added before calling the method.
Add listeners
pubnub.addListener({
// Messages
message: function (m) {
const channelName = m.channel; // Channel on which the message was published
const channelGroup = m.subscription; // Channel group or wildcard subscription match (if exists)
const pubTT = m.timetoken; // Publish timetoken
const msg = m.message; // Message payload
const publisher = m.publisher; // Message publisher
},
// Presence
// requires a subscription with presence
presence: function (p) {
const action = p.action; // Can be join, leave, timeout, state-change, or interval
const channelName = p.channel; // Channel to which the message belongs
const occupancy = p.occupancy; // Number of users subscribed to the channel
show all 72 linesRemove listeners
var existingListener = {
message: function () {
},
};
pubnub.removeListener(existingListener);
Listener status events
Category | Description |
---|---|
PNNetworkUpCategory | The SDK detected that the network is online. |
PNNetworkDownCategory | The SDK announces this when a connection isn't available, or when the SDK isn't able to reach PubNub servers. |
PNNetworkIssuesCategory | A subscribe event experienced an exception when running. The SDK isn't able to reach PubNub servers. This may be due to many reasons, such as the machine or device isn't connected to the internet; the internet connection has been lost; your internet service provider is having trouble; or, perhaps the SDK is behind a proxy. |
PNReconnectedCategory | The SDK was able to reconnect to PubNub. |
PNConnectedCategory | SDK subscribed with a new mix of channels. This is fired every time the channel or channel group mix changes. |
PNAccessDeniedCategory | Access Manager permission failure. |
PNMalformedResponseCategory | JSON parsing crashed. |
PNBadRequestCategory | The server responded with a bad response error because the request is malformed. |
PNDecryptionErrorCategory | If using decryption strategies and the decryption fails. |
PNTimeoutCategory | Failure to establish a connection to PubNub due to a timeout. |
PNRequestMessageCountExceedCategory | The SDK announces this error if requestMessageCountThreshold is set, and the number of messages received from PubNub (in-memory cache messages) exceeds the threshold. |
PNUnknownCategory | Returned when the subscriber gets a non-200 HTTP response code from the server. |
Unsubscribe (old)
Not recommended
The use of this method is discouraged. Use Unsubscribe instead.
When subscribed to a single channel, this function causes the client to issue a leave
from the channel
and close any open socket to the PubNub Network. For multiplexed channels, the specified channel
(s) will be removed and the socket remains open until there are no more channels remaining in the list.
Unsubscribing from all channels
Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken
and thus, there could be some gaps in the subscription that may lead to message loss.
Method(s)
To Unsubscribe from a channel
, you can use the following method(s) in the JavaScript SDK:
pubnub.unsubscribe({
channels: Array<string>,
channelGroups: Array<string>
}): Promise<UnsubscribeResponse>;
Parameter | Description |
---|---|
channels *Type: Array <string> | Specifies the channel ID to unsubscribe from. |
channelGroups Type: Array <string> | Specifies the channelGroups to unsubscribe from. |
Sample code
Unsubscribe from a channel:
Response
The output below demonstrates the response to a successful call:
{
"action" : "leave"
}
Other examples
Unsubscribing from multiple channels
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Example response
{
"action" : "leave"
}
Unsubscribing from multiple channel groups
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Unsubscribe all (old)
Not recommended
The use of this method is discouraged. Use Unsubscribe all instead.
Unsubscribe from all channels and all channel groups
Method(s)
unsubscribeAll()
Sample code
Returns
None