Salesforce CRT-450: Firing Aura Application Events

Learn the correct method for firing Aura application events in Salesforce CRT-450 certification exam. Discover the key differences between emit(), fireEvent(), fire(), and registerEvent() methods.

Question

Since Aura application events follow the traditional publish-subscribe model, which method is used to fire an event?

A. emit()
B. fireEvent()
C. fire()
D. registerEvent()

Answer

B. fireEvent()

Explanation

In Aura, application events follow the publish-subscribe model. To fire an event, the correct method to use is fireEvent(). This method is called on the component that is firing the event, passing the event object as a parameter.

Here’s an example of firing an Aura application event:

<!-- MyComponent.cmp -->
<aura:component>
<aura:registerEvent name="myEvent" type="c:MyEvent"/>

<lightning:button label="Fire Event" onclick="{!c.handleClick}"/>
</aura:component>

// MyComponentController.js
({
handleClick: function(component, event, helper) {
var myEvent = $A.get("e.c:MyEvent");
myEvent.setParams({ "message": "Hello, event!" });
myEvent.fire();
}
})

In this example, the component registers an event using <aura:registerEvent> and specifies the event name and type. The handleClick function in the controller retrieves the event using $A.get(), sets the event parameters using setParams(), and then fires the event using the fire() method.

The other options mentioned are incorrect:

• emit() is not a valid method in Aura for firing events.
• fire() is used to fire the event after it has been created and configured, but it is not the method for firing the event directly.
• registerEvent() is used to register an event in the component, but it does not fire the event.

Salesforce Certified Platform Developer I CRT-450 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Salesforce Certified Platform Developer I CRT-450 exam and earn Salesforce Certified Platform Developer I CRT-450 certification.