AngularJS

AngularJS is built around the belief that declarative programming should be used for building user interfaces and connecting software components, while imperative programming is better suited to defining an application's business logic.

Directives 

AngularJS directives are extended HTML attributes with the prefix ng-.

The ng-app directive initializes an AngularJS application.
The ng-init directive initializes application data.
The ng-model directive binds the value of HTML controls (input, select, textarea) to application data.

Data Binding

Data-binding: This is one of the core features in Angular. When the page loads, Angular binds the name of the input box to a variable of the same name in the data model and keeps the two in sync.

The {{ firstName }} expression, in the example above, is an AngularJS data binding expression.
Data binding in AngularJS, synchronizes AngularJS expressions with AngularJS data.
{{ firstName }} is synchronized with ng-model="firstName".

Filters

A filter can be added to an expression with a pipe character (|) and a filter.