Skip to main content

What Are Angular Decorators?

What Are decorators?
The Decorators are functions that modify JavaScript classes and it also used for attaching metadata to classes.

Directive decorator and metadata Properties -
@Directive({
    selector?: string
    inputs?: string[]
    outputs?: string[]
    host?: {...}
    providers?: Provider[]
    exportAs?: string
    queries?: {...}
})

Selector – It is a CSS selector that tells Angular to create an instance of this component wherever it finds the corresponding tag in template HTML.

For example, it is – <app-login></app-login>

CSS selector also triggers the instantiation of a directive.
The selector may be declared by element name, class name, attribute name, and attribute name & value.

Suppose we have a directive with an <input type="checkbox"> selector and the HTML looks like this.
<form>
 <label>Name -</label> <input type="text">
 <label>Are you agree? </label> <input type="checkbox">
<form>

The directive will only be instantiated on the <input type="checkbox"> element.

Inputs– The list of class property names to data-bind as component inputs

Outputs - The list of class property names that expose output events that others can subscribe too

Host– These properties use to map the class property to host element bindings for properties, events, actions, and attributes.

The host looks like this.
@Directive({
  selector: 'button',
  host: {'(click)': 'onClick($event.target)'}
})

Providers - list of providers available to this component and its children
Queries– To configure queries that can be injected into the component

For more detail kindly refer the link.... 
By Anil Singh | Rating of this article (*****)

Popular posts from this blog

nullinjectorerror no provider for httpclient angular 17

In Angular 17 where the standalone true option is set by default, the app.config.ts file is generated in src/app/ and provideHttpClient(). We can be added to the list of providers in app.config.ts Step 1:   To provide HttpClient in a standalone app we could do this in the app.config.ts file, app.config.ts: import { ApplicationConfig } from '@angular/core'; import { provideRouter } from '@angular/router'; import { routes } from './app.routes'; import { provideClientHydration } from '@angular/platform-browser'; //This (provideHttpClient) will help us to resolve the issue  import {provideHttpClient} from '@angular/common/http'; export const appConfig: ApplicationConfig = {   providers: [ provideRouter(routes),  provideClientHydration(), provideHttpClient ()      ] }; The appConfig const is used in the main.ts file, see the code, main.ts : import { bootstrapApplication } from '@angular/platform-browser'; import { appConfig } from ...

Top 15+ Angular 17 Interview Questions Answers | For Experienced Professionals as well

G Google team released the latest version of Angular – Angular 17 on November 6, 2023, creating a significant milestone for the super fast front-end development. What Are the New Features in Angular 17? 1.       Angular 17 is the highly anticipated release for the community, bringing many new exciting features, updates, and improvements. 2.       New Syntax for Control Flow in Templates - new @if, @switch, @for, @case, @empty @end control flow syntax 3.       Deferred Loading - @defer partial template 4.       The Angular signals API 5.       Angular SSR and client hydration 6.       Automatic Migration to Build-in Control Flow 7.       Build Performance with ESBuild 8.       By default, set this newly generated component as a standalone, and now we don't have an app module file. To use (ng...

SOLID-Liskov Substitution Principle (LSP) Real-Time Example in C#

The SOLID Principles are the design principles that enable us to manage several software design problems. These principles provide us with ways to move from tightly coupled code to loosely coupled and encapsulated real business needs properly. Also readable, adaptable, and scalable code. The SOLID Principles  guide developers as they write readable, adaptable, and scalable code or design an application. The SOLID Principles can be applied to any OOP program. The SOLID Principles were developed by computer science instructor and author Robert C. Martin. Now, SOLID principles have also been adopted in both agile development and adaptive software development. The 5 principles of SOLID are: 1.       Single Responsibility Principle (SRP) 2.       Open-Closed Principle (OCP) 3.       Liskov Substitution Principle (LSP) 4.       Interface Segregation Principle (ISP) 5. ...

List of Countries, Nationalities and their Code In Excel File

Download JSON file for this List - Click on JSON file    Countries List, Nationalities and Code Excel ID Country Country Code Nationality Person 1 UNITED KINGDOM GB British a Briton 2 ARGENTINA AR Argentinian an Argentinian 3 AUSTRALIA AU Australian an Australian 4 BAHAMAS BS Bahamian a Bahamian 5 BELGIUM BE Belgian a Belgian 6 BRAZIL BR Brazilian a Brazilian 7 CANADA CA Canadian a Canadian 8 CHINA CN Chinese a Chinese 9 COLOMBIA CO Colombian a Colombian 10 CUBA CU Cuban a Cuban 11 DOMINICAN REPUBLIC DO Dominican a Dominican 12 ECUADOR EC Ecuadorean an Ecuadorean 13 EL SALVA...

39 Best Object Oriented JavaScript Interview Questions and Answers

Most Popular 37 Key Questions for JavaScript Interviews. What is Object in JavaScript? What is the Prototype object in JavaScript and how it is used? What is "this"? What is its value? Explain why "self" is needed instead of "this". What is a Closure and why are they so useful to us? Explain how to write class methods vs. instance methods. Can you explain the difference between == and ===? Can you explain the difference between call and apply? Explain why Asynchronous code is important in JavaScript? Can you please tell me a story about JavaScript performance problems? Tell me your JavaScript Naming Convention? How do you define a class and its constructor? What is Hoisted in JavaScript? What is function overloadin...