Why queryParams are empty

I'm using javascript, it's working very nice :

var action = new URLSearchParams(window.location.search).get('action');

Because component is loaded before the actual routing applied. Add { enableTracing: true } to the RouterModule to see what is happening behind the scene.

RouterModule.forRoot([], { enableTracing: true })

https://stackblitz.com/edit/angular-boghpy?file=src/app/app.module.ts