NG Interview Set I - NgModules Questions

Question 1

What is the purpose of NgModule?

Answer 1

• It’s to give Angular information on a particular module’s contents, through decorator properties like: declarations, imports, exports, providers, etc.

Question 2

How do you decide to create a new NgModule?

Answer 2

• Typically for a nontrivial feature in an application, that will involve a collection of related components and services

Question 3

What are the attributes that you can define in an NgModule annotation?

Answer 3

• Declarations, imports, exports, providers, bootstrap

Question 4

What is the difference between a module’s forRoot() and forChild() methods and why do you need it?

Answer 4

• forRoot and forChild are conventional names for methods that deliver different import values to root and feature modules

Question 5

What would you have in a shared module?

Answer 5

• Common components, directives, and pipes used in other modules in your application

Question 6

What would you not put shared module?

Answer 6

• Services that should not have multiple instances created for the application

Question 7

What module would you put a singleton service whose instance will be shared throughout the application (e.g. ExceptionService andLoggerService)?

Answer 7

• Root Module

Question 8

What is the purpose of exports in an NgModule?

Answer 8

• Provide components, directives, pipes to other modules for their usage

Question 9

Why is it (potentially) bad if SharedModule provides a service to a lazy loaded module?

Answer 9

• You will have two instances of the service in your application, which is often not what you want

Question 10

Can we import a module twice?

Answer 10

• Yes, and the latest import will be what is used

Question 11

Can you re-export classes and modules?

Answer 11

• Yes

Question 12

What kind of classes can you import in an angular module?

Answer 12

• Components, pipes, directives

Question 13

What is the providers property used for in a module’s NgModule metadata?

Answer 13

• To provide a list of service cerators that this module contributes to the global collection of services

Question 14

What is bootstrapping in Angular?

Answer 14

• The mechanism that launches the application in Angular, loading the root module (typically called AppModule) which loads one or more bootstrapped components into the application’s DOM