Lightning Aura Components Developer Guide

What Is the Lightning Component Framework?
Quick Start
Creating Components
Using Components
Communicating with Events
Actions and Events
Handling Events with Client-Side Controllers
Component Events
Application Events
Application Event Propagation
Create Custom Application Events
Fire Application Events
Handling Application Events
Application Event Example
Event Handler Behavior for Active Components
Event Handling Lifecycle
Advanced Events Example
Firing Events from Non-Aura Code
Events Best Practices
Events Fired During the Rendering Lifecycle
Events Handled in the Salesforce Mobile App and Lightning Experience
System Events
Communicating Across the DOM with Lightning Message Service
Creating Apps
Styling Apps
Developing Secure Code
Using JavaScript
Working with Salesforce Data
Testing Components with Lightning Testing Service
Debugging
Performance
Reference
PDF

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Create Custom Application Events

Create a custom application event using the <aura:event> tag in a .evt resource. Events can contain attributes that can be set before the event is fired and read when the event is handled.

Use type="APPLICATION" in the <aura:event> tag for an application event. For example, this c:appEvent application event has one attribute with a name of message.

1<!--c:appEvent-->
2<aura:event type="APPLICATION">
3    <!-- Add aura:attribute tags to define event shape.
4         One sample attribute here. -->
5    <aura:attribute name="message" type="String"/>
6</aura:event>

The component that fires an event can set the event’s data. To set the attribute values, call event.setParam() or event.setParams(). A parameter name set in the event must match the name attribute of an <aura:attribute> in the event. For example, if you fire c:appEvent, you could use:

1event.setParam("message", "event message here");

The component that handles an event can retrieve the event data. To retrieve the attribute in this event, call event.getParam("message") in the handler’s client-side controller.