# Event Handling

The Conversations SDK is event-driven. Objects from the SDK will emit real-time events based on state changes in your Conversations instance. You can use these events to update your application's state and UI.

## Which objects emit events?

The SDK emits events on several objects (i.e. Client, Conversation, User, etc.).

These events are emitted, for example, when:

* A new Message is added to a Conversation that you are participating in
* The connection state of your Client changes
* A Participant leaves a Conversation
* A User comes online
* Your Access Token is about to expire
* The `friendlyName` of a Conversation is updated

A full list of events and objects can be found by referring to our generated SDK documentation:

* [JavaScript](https://media.twiliocdn.com/sdk/js/conversations/latest/docs)
* [Android](https://media.twiliocdn.com/sdk/android/conversations/latest/docs)
* [iOS](https://media.twiliocdn.com/sdk/ios/conversations/latest/docs)

Event Handling

```js
/* event handler examples */

client.on("conversationUpdated", ({conversation, updateReasons}) => {
    // Fired when the attributes or the metadata of a conversation have been updated
});

conversation.on("messageUpdated", ({message, updateReasons}) => {
    // Fired when data of a message has been updated.
});

participant.on("updated", ({participant, updateReasons}) => {
    // Fired when the fields of the participant have been updated.
});
```

```ts
/* event handler examples */

import {
    Conversation,
    ConversationUpdateReason,
    Message,
    MessageUpdateReason,
    Participant,
    ParticipantUpdateReason
} from "@twilio/conversations";

client.on("conversationUpdated", ({conversation, updateReasons}: {
    conversation: Conversation,
    updateReasons: ConversationUpdateReason[]
}) => {
    // Fired when the attributes or the metadata of a conversation have been updated
});

message.on("updated", ({message, updateReasons}: {
    message: Message,
    updateReasons: MessageUpdateReason[]
}) => {
    // Fired when data of a message has been updated.
});

participant.on("updated", ({participant, updateReasons}: {
    participant: Participant,
    updateReasons: ParticipantUpdateReason[]
}) => {
    // Fired when the fields of the participant have been updated.
});
```

## Best practices and tips for listening to events

* For the JavaScript SDK, you can receive most events from the Client object. This is more performant in browsers and recommended over setting up duplicate handlers on each Conversation/User. You can also set up handlers on specific objects (e.g. Conversation, User) as needed.
* For the iOS SDK, all events are emitted at the top level `TwilioConversationsClientDelegate`.
* For the Android SDK, only some events are emitted from the `ConversationsClientListener`. Other events are available from the `ConversationListener` and `MediaUploadListener`.

## What's Next?

As a next step, you can visit the following guides:

* Learn [How to work with Conversations](/docs/conversations/working-with-conversations).
* Check out our [Conversations JavaScript Quickstart](/docs/conversations/javascript/exploring-conversations-javascript-quickstart) to test the code by yourself.