> For the complete documentation index, see [llms.txt](https://docs.pixiebrix.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pixiebrix.com/developing-mods/developer-concepts/types-of-mods/trigger/working-with-custom-events.md).

# Working with Custom Events

{% hint style="info" %}
[Release 1.7.0](/release-notes/release-notes-archive/release-1.7.0.md) in June 2022 introduced support for Custom Events.
{% endhint %}

Custom Events can be used to define your own custom Triggers, and control when a Sidebar Panel mod refreshes.

PixieBrix uses the [DOM Event API](https://developer.mozilla.org/en-US/docs/Web/Events/Creating_and_triggering_events) standard. Therefore, custom events can be used to communicate bi-directionally with the host page.

### Emitting/Dispatching a Custom Event

To emit a custom event, use the [Emit a Custom Event](https://www.pixiebrix.com/marketplace/fcd0a884-fb83-4d82-a1c4-932287ae79f4/emit-a-custom-event/) brick. The brick takes two inputs:

* `eventName`: a unique name for the event. The name should be globally unique
* `data`: an optional data payload

PixieBrix dispatches the event on the root document of the frame.

### Running a Trigger on a Custom Event

To run a trigger on a Custom Event, choose “Custom Event” from the Trigger dropdown and configure the trigger:

* Custom Event: the name of the event. Should match the `eventName` in your use of Emit a Custom Event (see Emitting/Dispatching a Custom Event above)
* Element: an *optional* selector controlling the elements on which to listen for the event. Use when running triggers for events from the host page. The Emit a Custom Event brick emits events on the document itself.

<figure><img src="/files/ARdN7sp8DClF2Chrktne" alt=""><figcaption></figcaption></figure>

If the event includes data, that data will be available to the Trigger mod bricks as `@input.event`

If the event includes data, that data will be available to the Trigger mod bricks as `@input.event`

<figure><img src="/files/pQDTdzw4zILVm6rDf9vG" alt=""><figcaption></figcaption></figure>

### Refreshing a Sidebar Panel on Custom Event

Custom Events can also be used to control Sidebar Panel updates. To configure a Sidebar Panel to update on a custom event, choose “Custom Event” from the Panel Refresh > Trigger dropdown.

Then, configure the event to listen for:

* Custom Event: the name of the event. Should match the `eventName` in your use of Emit a Custom Event (see Emitting/Dispatching a Custom Event above)

<figure><img src="/files/e3qsna7s4grK5h8NkNCc" alt=""><figcaption></figcaption></figure>


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