Angular Ngclass/ngif Not Rerendering On Changes

I'm working on an Angular project where I need to have one class or another depending on a variable (and they have to change live, without refreshing). I tried using *ngIf/else and

Solution 1:

In your component, favSongs never gets updated: it gets value assigned in the ngOnInit (so, once in the lifetime of the component), and that's it. setToFav only manipulates local storage (favSongs doesn't automatically get updated, you have to to it explicitly).