NG Interview Set I - Component/Directive Questions

Question 1

What is the minimum definition of a component?

Answer 1

• A class with a Component decorator specifying a template

Question 2

What is the difference between a component and a template?

Answer 2

• A component is a directive with a template (representing a view)

Question 3

What are different kinds of directives supported in Angular 2?

Answer 3

• Structural, component, and attribute directives

Question 4

How do components communicate with each other?

Answer 4

• Various ways - for example: Input/Output properties, services, ViewChild/ViewContent

Question 5

How do you create two way data binding in Angular 2.0?

Answer 5

• By using the two-way binding syntax [()] (along with ngModel, if you’re doing this in the context of a form control element)

Question 6

How would you create a component to display error messages throughout your application?

Answer 6

• Implement your own ErrorHandler and configure it in the list of providers for the modules you want it used in

Question 7

How would you support logging in your Angular app?

Answer 7

• One way would be to use angular2-logger, which is a package inspired by log4j

Question 8

How would you use the ngClass directive?

Answer 8

For example:

< div [ngClass]= " {firstCondition: ' class1' , secondCondition: ' class2' } " > ... < /div >

Question 9

What are dynamic components?

Answer 9

• Components that are added at runtime (i.e. not fixed). For example, an ad banner component that is determined at runtime