Navigation Started
An event indicating that the navigation has been started. This is also fired by same-document navigations, such as fragment navigations or pushState/replaceState, which will not result in a document change. To filter these out, use the isSameDocument method.
Note that more than one navigation can be ongoing in the same frame at the same time (including the main frame). Note that there is no guarantee that the NavigationFinished will be fired for any particular navigation before this event is called on the next.