问题
why ActivatedRoute in @angular\router params is observable ?
I'm wondering why do I need to subscribe for Params ? and why params are async is there a case the componenet of the route will be created but the params still not populated ?
and is there a way to just get the value without an observable ?
回答1:
You can use
route.routerState.params
You can subscribe because when your application navigates to the same route with just another parameter value, the component is not recreated and you have no way of knowing when the parameters have changes.
With subscribing to parameters you get notified, that a route action has happened where only the parameter value changed.
回答2:
The matrix parameters scoped to this route. The observable will emit a new value when the set of the parameters changes.
The reason that the params property on ActivatedRoute is an Observable is that the router may not recreate the component when navigating to the same component. In this case the parameter may change without the component being recreated.
来源：https://stackoverflow.com/questions/40577118/why-activatedroute-in-angular-router-params-is-observable