If your controller has any of these methods, they will be called during specific moments during the lifecycle of your controller.
onInit() is called after the custom element is
connected to a DOM. It's a good place to set up your initial
properties. Child elements are not yet attached to the DOM,
templates are not parsed, and most other things are not yet set
up.
onParse() is fired when all child nodes are parsed
for light DOM elements and is fired immediately after
onInit() for shadow DOM elements. If you are doing
your own light DOM
content projection, this
would be an important method to use. With lengthy HTML, there
might be multiple chunks of child nodes added as children to the
custom element. This method is called after all of them are
added, using a technique of watching for the document's content
to be loaded and using a mutation observer to see if any parents
have next siblings.
onViewInit() will be executed at the very end after
the custom element is connected to the DOM and the template has
also been attached and processed. At this point, all children
are in the DOM, #ref directives are set up, and
your element is basically live.
onChange(propertyName, oldValue, newValue) will be
triggered whenever a monitored property is updated. Monitored
properties are the ones that are referenced in a template, plus
any attribute or property listed in the config. Differences are
detected by using === (strict equals), so changes
to immutable objects trigger change detection more easily.
Calling update() (see
Utilities) will also call
onChange() for all attributes and properties that
are copied into the controller.
onDestroy() is when the controller is being
detached from the custom element and the custom element is being
disconnected from the DOM.