Angular is a Platform and Framework for Building single-page Client Applications using HTML and TypeScript
It is written in TypeScript therefore it uses all high-level Concepts of typeScript like Decorators
It is a component-based Framework for Building scalable Web Applications
Features
Angular includes Routing, Form Management and Client-Server Communication
It contains Developer Tools to help the Development, Building, Testing and Updating of Code
Architecture
Every Module is decorated with the Decorator NgModule
A Module references a Component which is decorated with the Decorator Component
Each Module has a Root Module that contains all Declarations of its Components
Interpolation
Interpolation refers to embedding Expressions into marked up Text
Property Binding
Property Binding sets Values for Properties of HTML Elements or Directives
From Parent to Child Component Properties are passed via Props and @Input()
From Child to Parent Component Properties are passed via Events and @Output()
Event Binding
Event Binding listens for and responds to User Actions
Two-Way Binding
Two-Way Binding allows Components to share simultaneously Data between each other
Directives
Directives are Classes that add additional Behavior to Elements
Different Types of Directives are:
Components that are used with a Template (like NgClass, NgStyle, NgModel)
Attribute Directives that change the Appearance or Behavior of an Element, Component or another Directive
Structural Directives that change the DOM Layout by Adding and Removing DOM Elements (like NgIf, NgSwitch, NgFor)
Pipes
Pipes are Functions to use in Template Expressions that accept an Input Value and return a transformed Value
Lifecycle
A Component Instance has a Lifecycle that start when Angular instantiates the Component Class and renders the Component View along with its Child Views
The Lifecycle continues with Change Detection, as Angular checks to see when data-bound Properties change, and updates both the View and the Component Instance as needed
The Lifecycle ends when Angular destroys the Component Instance and removes its rendered Template from the DOM
Directives have a similar Lifecycle, as Angular creates and destroys Instance in the Course of Execution
Service
Service is a Category that comprehensive any Value, Function or Feature that an Application needs
A Service is a Class with a narrow, well-defined Purpose
It should do something specific and do it well
A Component should be clean and lean therefore a Service will carry the heavy Loading of Computation
It should present Properties and Methods for Data Binding and the Application Logic therefore a Component can delegate certain Tasks to Services
@Injectable registers a Service in the service Container from which a Component can inject it
Dependency Injection
Dependency Injection is wired into the Angular Framework and used everywhere to provide new Components with the Services they need
It allows Components to consume Services
A Component can inject a Service and having Access to that Service Class
