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Angular 4

Building Blocks of Angular 4

There are 5 section cover in this blog ..

  1. module 
  2. component 
  3. template
  4. metadata
  5. data-binding

Module

module is a class with ng-module metadata, every angular app has at least one root module encapsulation of different similar functionalities 

how to declare :


@ngmodule({ //decorator
    declareation :[AppComponent,TaskComponent],         //declare Component
    imports :[BrowserModule,FormsModule,HttpModule], //import Module
    providers:[],
bootstrap:[AppComponent] //providing services to all modules component
})

Component

Angular 4 components are simply classes that are designated as a component with the help of a component decorator. 

Every component has a defined template which can communicate with the code defined in the component class. So, let's take a close look at how components are structured.


Metadata

metadata describes how to process the class ,decorator is used to attach metadata

example :  myclass + @Component({---}) /// decorator ==> Component{}
appclass + @NgModule({....}) ===>Module



Templates

used to define view of a component 
looks like HTML, expect for a few differences .
describes how the component is rendered on the page.



Data-Binding

data-binding plays an important role in communication between a template and its component
{{value}}
1.interpolation     DOM <======================= component
[property]="value"
2.property binding   DOM <======================= component 
(event)="event handler"
3.event binding   DOM ========================> component
[{ngModel}]
4. 2 way data binding   DOM <=======================> component



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