How Access Between Angular

• From Parent to access child component
• @ViewChild()
• Pass Data between child and parent component
• @Input() 
• data from parent to child
• @Input() item = ''; // decorate the property with @Input()
• Directive From Parent Component
• <app-item-detail [item]="currentItem"></app-item-detail>
• @Output()
• data from child to parent with the help of the event.
• to raise event must have EventEmitter

Angular Question

• Type of Data Binding
• One Way Binding
• Interpolation Bnding
• data move in one direction from components (typescript) to HTML
• <p>{{ message }}</p> 
• Property Binding
• set properites to HTML elements.
• [value]="user.email" or <img [src]="imageUrl"> 
• Two Way Binding 
• component and view are always in sync
• Changes in user interface to model state.
• Changes in model state reflect to user interface
• <input [(ngModel)]="name">
• Event Binding
  
• One Way Binding
• for event trigger
• <button (click)="doSomething()">Click me</button> 
  
  
  
• How does one share data between components in Angular? 
• Parent to child using @Input decorator 
• 
  
• Child to parent using @ViewChild decorator 
• Child to parent using @Output and EventEmitter 

• Decorators
• Design Pattern & function
• modification to a class, service or filter
• 4 Types
• Class Decorators
• Property Decorators
• Method Decorators
• Parameter Decorators
• Advantages
• MVC architecture
• Modules
• componentes
• directives
• pipe
• services
• Dependency Injection
• component dependent on other components can easily worked around
• Others
• clean and maintainable code
• reusable components
• data binding
• unit testing
• Directives
• attributes allow user write new HTML syntax
• 3 Types
• Component Directives
• Structural Directives
• Attribute Directives
• 
  
• 
  myHighlist is Directives
• Template
• HTML View
• seperate template file such **.html
• Template Statements
• properties or methods
• (click)='addUser()"
• addUser is template
• Promises and Observables
• Promises
• emit single value at a time
• Execute immediately after creation and not cancellable
• Push Errors to child Promises
• Observables
• execute when subscribe()
• emit Mutiple value over a period of time
• perform forEach, filter and retry
• Deliver errors to subscribers.
• When unsubsribe() is called, listener stop receive further values.

• Observable	Promise
  Declarative: Computation does not start until subscription so that they can be run whenever you need the result	Execute immediately on creation
  Provide multiple values over time	Provide only one
  Subscribe method is used for error handling which makes centralized and predictable error handling	Push errors to the child promises
  Provides chaining and subscription to handle complex applications	Uses only .then() clause

• Difference AngularJS and Angular

• AngularJS	Angular
  It is based on MVC architecture	This is based on Service/Controller
  It uses JavaScript to build the application	Uses TypeScript to build the application
  Based on controllers concept	This is a component based UI approach
  No support for mobile platforms	Fully supports mobile platforms
  Difficult to build SEO friendly application	Ease to build SEO friendly

• 
  

Dependency Injection 2

What is Dependency Injection

• Produce a loosely coupled code
• Any change in the class without affecting other object.
• Type of DI
• Constructor Injection
• parameter to inject dependencies in a class
• One parameterized constructor but no default constructor and you need to pass specified values to the constructor
• 
  
  
  
  
• Setter Injection
• through properties of a class
• 
  
  
  
  
• Interface-based injection
• through method
• 
  
  
  
• Advantage
• Maintainability
• maintain code structure, single principle
• Flexibility
• loosely coupled code, flexible to use different ways.
• Testability
• easy to do unit testing
• Readability
• Logic in constructor.