AngularJS Interview Questions
1 .
What is AngularJS ?
Angular JS is an JavaScript-based open-source front-end web application framework mainly maintained by Google. AngularJS is based on the MVC pattern (Model View Control), it's mainly used in Single Page Application (SPA) projects.
2 .
Name the key features of AngularJS ?
The key features of AngularJS are:

MVC
Validations
Modules
Directives
Templates
Scope
Expressions
Data Binding
Filters
Services
Routing
Dependency Injection
Testing
and more...
3 .
What are directives in AngularJS ?
A core feature of AngularJS, directives are attributes that allow you to invent new HTML syntax, specific to your application.

The different types of directives are :

Element directives
Attribute directives
CSS class directives
Comment directives
4 .
What are the controllers in AngularJS ?
Controllers are JavaScript functions that are bound to a particular scope. They are the prime actors in AngularJS framework and carry functions to operate on data and 

decide which view is to be updated to show the updated model based data.
5 .
What are the services in AngularJS ?
AngularJS come with several built-in services. For example $https: service is used to make XMLHttpRequests (Ajax calls). Services are singleton objects which are instantiated only once in app.
6 .
What are the filters in AngularJS ?
Filters select a subset of items from an array and return a new array. Filters are used to show filtered items from a list of items based on defined criteria.
7 .
Explain directives in AngularJS.
Directives are markers on DOM elements (such as elements, attributes, css, and more). These can be used to create custom HTML tags that serve as new, custom widgets. 

AngularJS has built-in directives (ng-bind, ng-model, etc)
8 .
What is MVC ?
In the MVC pattern, the different aspects of the application are broken into components to separate responsibilities. The Model contains the data and logic, the View contains the visual layout and presentation is following :

Model : It is the lowest level of the pattern responsible for maintaining data.

View : It is responsible for displaying all or a portion of the data to the user.

Controller : It is a software Code that controls the interactions between the Model and View.

Ajax Interview Questions
9 .
Explain ng-app directive.
ng-app directive defines and links an AngularJS application to HTML. It also indicate the start of the application.

<body ng-app ="app_name">
  //some content.....
</body>

10 .
What are expressions in AngularJS ?
Expressions are the code snippets that resolves to a value. AngularJS expressions are placed inside {{expression}}. 

For example :
{{9+18}}  

AngularJS supports one-time binding expressions.