How to pass an event to another unrelated component (Angular 2)?

Question

Angular

On all pages of the site there will be left navigation , like a toaster:
And also on all pages there will be a button on the right , which should toggle left navigation
I made a left navigation component, this is how I connect it to all pages in the root html:

<left-aside></left-aside>
<router-outlet></router-outlet>

Answer 1

RxJS

Answer 2

According to the description of the task, I do not see why this should be done in each component. Enough only in left-aside.
In general, through any service, you can do this in the usual way. And here rxjs is not clear.