If and else to share dialog function to use from another component

Currently I have 2 working components assuming the name is component A and B. Component B has a dialog attach to it from a button and Component A has no dialog attach to their button but that button has a routerlink that goes to component B page. I'm not sure if it will work. How do I write a if and else statement to trigger the modal from component B function to use on component A.

Do I still need get route from component B?

Appreciate some help with thanks.