Angular 2 Shared Data Service is not working

Question

I have built a shared data service that\'s designed to hold the users login details which can then be used to display the username on the header, but I cant get it to work.

Answer 1

Add it in @NgModule.providers array of your AppModule:

if you add it in @Component.providers array then you are limiting the scope of SharedDataService instance to that component and its children.

in other words each component has its own injector which means that headerComponentwill make its own instance of SharedDataServiceand loginComponent will make its own instance.