Ionic 4 Vanilla Router Parameters

Hello. I need a router with parameters but i do not use Angular or AngularJS. I’ve heard of stencil, but I dont know how to install. How can I use routers with parameters. I’ve made that:

<ion-route url="/test/:testId" component="page-test"></ion-route>

but how can I get the parameter testId?
Thank you…

Have you tried declaring it as a property of the page test component?