Components

What is the difference between directive and the component?
Difference between ngOnChanges and ngDoCheck?
How to send data from child to parent?
What is Change detection and type of change detection?
What is view encapsulation?
What is Shadow dom?
What is EventEmitter? Can we use it in service if yes then how to tell the use case?
Difference between ngOnint and Constructor?

Templates

Can we put maths expressions in interpolation?
What is event binding?
What is the difference between impure and pure pipe?
Can we apply pipe in ngFor ? How to get the length of the filtered result?
Make a groupby pipe?
What is property binding?
What is attribute binding?
What is a template reference variable? What are all the use cases?

Directives

What are types of directives available ?
Why * (start) asterisk before ngFor ?
Can we use ngFor and ngIf on the same element?
Write syntax for custom directive ?
Difference between Attribute and structure directive?
What is ng template , ng container, ng-content, ng template outlet?
Where to use ngSwitch ? Write the syntax codewise ?

Dependency Injection

What is Injectable?
What is provided in types (root etc)?
Difference between public and private service injection?
What is a provider?
How to create multiple instances of a service (sandboxing)?

Routing & Navigation

What is codespliting?
What is lazy loading ?
How to get current route information?
What is a wildcard route?
How set display a 404 page?
How to do nesting routing?
What is the relative path?
Difference between query param and param?
What is a route guard? Use of canactivate?
Difference location strategies ?
What activate route and snapshot route?
Difference between for root and for child ?

Forms

Difference between Reactive form and template driven form?
What is a control value accessor?
What is the use of a formArray ?
What is the use of formGroup?
In which form reactive or template driven form model is implicit?
How does data flow in both forms?
What is mutability of data model?
What is form validation? How to define custom validation on both forms?
How to put validation error in template driven form?
Difference between sync and async validator function?
What is abstract control?
How to put a validation class on the form element?
Difference between set and patch value?

HTTP Client

What is an http interceptor?
What are different options in request ?
What are different response type?
How to cancel any request?
How to handle multiple request hit one after another any once can come first or second etc?
What is JSONP?
How to read non json data?
How to handle errors?
How to retry a failed request?
How to handle timeout ?

Testing

What is code coverage? How to check it?
How to test services with multiple dependencies ?
What is spy object?
What is testbed ?
What is a component fixture?
How to do query in html dom in testing?
What is the use of detectChanges?
How to test async service?
How to test input and output ?
How to test routing?
How to test pipes?

Internationalization (i18n)

How to provide the translation files?
How to localize currency ?
How to localize time?

Animation

What is multiple transition state?
How to animate entering and leaving view?
What is complex animation sequence ?
What is stagger group and sequence?

Schematics

How to generate module with routing using cli
How to create component without spec file?

PWA and Service worker

What is PWA Progressive web app ?
What is service work?
Is Server Side render support service worker?
How make app aware new version is available?

RxJS

Explain the operator catchError,retry?
What is Of and from operator?
Explain switchmap?
Define Subject and its types with difference?
Difference between hot and cold observable?
Define unicasting and multicasting?
After an observable error will it get new value?

Security

How to keep your app secure?
How to bypass angular security?

Performance and optimization

How you optimize your app?
Difference between defer and async?
What is CDN?
How to make components lighter?
How many ngmodel can we put in single page?
What is tree shaking?