Overview

Events serve as a mechanism for initiating specific actions, often employed to trigger particular behaviors. They collaborate with various actions to establish dynamic interactions within an application.

For instance, when a user interacts with a webpage by clicking a button, you have the flexibility to determine the response, whether it involves invoking a function or opening another webpage. Furthermore, events can be activated in response to updates in a Qodly Source.

Within Qodly Studio, events play a pivotal role in executing code on the Qodly web server, without requiring any supplementary JavaScript.

Types of Events

Events can be set to trigger either when end-users perform specific actions or when qodlysources are updated.

User events

You can configure events to activate in response to specific actions performed by end-users, such as clicking buttons, moving the mouse cursor, and more.

Typical user events include On Click, On DblClick, On MouseEnter, On Keyup, and others. The available events may vary depending on the selected component, and detailed documentation can be found in the Triggers and Events section on each component's page.

Qodly Source events

Besides events triggered by end-user actions, events can also be automated to respond when qodlysources undergo changes. The primary event for qodlysources is the On Change event.

When the On Change event is linked to a qodlysource, it will trigger in the following scenarios:

Trigger	Description
Qodly Source	The reference pointed to by the qodlysource changes in the web browser (not on the server) The entity is touched
Entity Qodly Source	The contents of the entity attribute change
Entity Selection Qodly Source	The reference pointed by the qodlysource changes in the web browser (not on the server) An entity is added to the entity selection
Scalar Qodly Source	The contents of the scalar qodlysource change

Circular Dependency Risk

Using the Reload standard action within an On Change event can create a circular dependency. This causes Qodly Studio to enter an infinite loop of reloading, which results in the application freezing.

When you set an On Change event to reload the qodly source, the following happens:

• A change in the qodly source triggers the On Change event.

• The On Change event contains a Reload standard action.

• The Reload standard action causes the qodly source to reload, which is considered a change.

• This change triggers the On Change event again.

This creates a loop:

Change → On Change Event → Reload Standard Action → Change → On Change Event → Reload Standard Action → ...

This loop continues indefinitely until Qodly Studio runs out of resources or crashes, leading to the application freezing.