At which point is the OnReady event triggered?

The OnReady event is triggered when the Document Object Model (DOM) is fully loaded. This means that all the HTML elements on the page are fully constructed and can be manipulated using JavaScript. Timing is crucial in web development; hence, this event is essential because it ensures that any code you want to execute after the page is loaded runs at the appropriate time, ensuring that all elements are accessible and ready for interaction.

This event allows developers to set up any initial states, bindings, or interactivity immediately after the page content is available for user interaction, making it a critical event in the lifecycle of a web application. In contrast, the other scenarios described involve different triggers that do not relate to the complete loading of the DOM. For instance, button clicks, data fetching, or closing screens happen at different lifecycle stages and do not determine the readiness of the DOM for further scripting activities.