Adds an event handler that runs when an application page's URL changes.
The event handler set by the onChange() function runs when the location is changed
but the change doesn't trigger navigation. This situation occurs when navigating between
subitems on a page that is managed by a full-page application.
For example, a store product page is a full-page application. When a product page's path
changes because it is switching between items, no actual navigation is taking place. You
can use the onChange() event handler to determine when a new product is displayed and
perform any necessary partial updates on the current page.
The onChange() function can only be used when browser
rendering happens,
meaning you can only use it in frontend code after the page is ready.
To determine if a page is managed by a full-page application, use the wix-site-frontend
currentPage property or getSiteStructure()
function to retrieve a StructurePage object that
corresponds to the page. If the object contains an applicationId value, then the
page is managed by a full-page application.
handler(event: Location): void The name of the function or
the function expression to run when the location changes.