---title: PubSub.Clientsidebar_label: Clientsidebar_position: 0---import MethodOff from ../../_common/_method_off.mdx;import MethodOn from ../../_common/_method_on.mdx;import MethodOnce from ../../_common/_method_once.mdx;import MethodRemoveAllListeners from ../../_common/_method_removealllisteners.mdx;You can use the Client object to build a messaging system into the browser.Example usage:jsimport { PubSub } from @signalwire/js;const pubSubClient = new PubSub.Client({ token: , // get this from the REST APIs});await pubSubClient.subscribe([mychannel1, mychannel2]);pubSubClient.on(message, (message) => { // prettier-ignore console.log(Received, message.content, on, message.channel, at, message.publishedAt);});await pubSubClient.publish({ channel: mychannel1, content: hello world,});## Constructors### constructor• **new Client**(pubSubOptions)Creates a new PubSub client.#### Parameters| Name | Type | Description || :-------------------- | :------- | :----------------------------------------------------------------------------------------------------------- || pubSubOptions | Object | - || pubSubOptions.token | string | SignalWire Chat token that can be obtained from the [REST APIs](pathname:///rest/generate-a-new-chat-token). |#### Examplejsimport { PubSub } from @signalwire/js;const pubSubClient = new PubSub.Client({ token: ,});## Methods### disconnect▸ **disconnect**(): voidDisconnects this client. The client will stop receiving events and you will need to create a new instance if you want to use it again.#### Returnsvoid#### Examplejsclient.disconnect();---### getAllowedChannels▸ **getAllowedChannels**(): PromiseReturns the channels that the current token allows you to subscribe to.#### ReturnsPromiseAn object whose keys are the channel names, and whose values are thepermissions. For example:js{ my-channel-1: { read: true, write: false }, my-channel-2: { read: true, write: true },}#### Examplesjsconst pubSubClient = new PubSub.Client({ token: ,});const channels = await pubSubClient.getAllowedChannels();console.log(channels);---### off---### on---### once---### publish▸ **publish**(params): PromisePublish a message into the specified channel.#### Parameters| Name | Type | Description || :--------------- | :---------------------- | :------------------------------------------------------------------------------------------ || params | Object | - || params.channel | string | Channel in which to send the message. || params.content | any | The message to send. This can be any JSON-serializable object. || params.meta? | Record | Metadata associated with the message. There are no requirements on the content of metadata. |#### ReturnsPromise#### ExamplesPublishing a message as a string:jsawait pubSub.publish({ channel: my-channel, content: Hello, world.,});Publishing a message as an object:jsawait pubSub.publish({ channel: my-channel, content: { field_one: value_one, field_two: value_two, },});---### removeAllListeners---### subscribe▸ **subscribe**(channels): PromiseList of channels for which you want to receive messages. You can only subscribe to those channels for which your token has read permission.Note that the subscribe function is idempotent, and calling it again with a different set of channels _will not_ unsubscribe you from the old ones. To unsubscribe, use [unsubscribe](./pubsub-client.mdx#unsubscribe).#### Parameters| Name | Type | Description || :--------- | :--------------------- | :----------------------------------------------------------------------------------------------------- || channels | string \| string[] | The channels to subscribe to, either in the form of a string (for one channel) or an array of strings. |#### ReturnsPromise#### Examplejsconst pubSub = new PubSub.Client({ token: ,});pubSub.on(message, (m) => console.log(m));await pubSub.subscribe(my-channel);await pubSub.subscribe([chan-2, chan-3]);---### unsubscribe▸ **unsubscribe**(channels): PromiseList of channels from which you want to unsubscribe.#### Parameters| Name | Type | Description || :--------- | :--------------------- | :--------------------------------------------------------------------------------------------------------- || channels | string \| string[] | The channels to unsubscribe from, either in the form of a string (for one channel) or an array of strings. |#### ReturnsPromise#### Examplejsawait pubSub.unsubscribe(my-channel);await pubSub.unsubscribe([chan-2, chan-3]);---### updateToken▸ **updateToken**(token): PromiseReplaces the token used by the client with a new one. You can use this method to replace the token when, for example, it is expiring, in order to keep the session alive.The new token can contain different channels from the previous one. In that case, you will need to subscribe to the new channels if you want to receive messages for those. Channels that were in the previous token but are not in the new one will get unsubscribed automatically.#### Parameters| Name | Type | Description || :------ | :------- | :------------- || token | string | The new token. |#### ReturnsPromise#### Examplejsconst pubSubClient = new PubSub.Client({ token: })pubSubClient.on(session.expiring, async () => { const newToken = await fetchNewToken(..) await pubSubClient.updateToken(newToken)})## Events### message• **message**(message)A new message has been received.#### Parameters| Name | Type || :-------- | :--------------------------------------------------------------------- || message | [PubSubMessage](./pubsub-pubsubmessage.md) |---### session.expiring• **session.expiring**()The session is going to expire. Use the [updateToken](#updatetoken) method to refresh your token.
