What classes should not be added to declarations?

[hp-singh-53e2639c (Harjas Preet Singh)]

What classes should not be added to declarations?

[anik-acharjee]

The classes that should not be added to declarations are -

1. A class that are declared in an app module, Ng module or even in third-party module.
2. An array of directives, imported mainly from another module.
3. Module classes.
4. Service classes.
5. Non-angular classes and different another objects.