#angular13

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[nareshitprasanna7]

👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar.

🛑 Free Demo 🛑 ✍️Enroll Now: https://bit.ly/3K77Rcb 👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar. 📅Demo On: 11th July @ 06:00 AM (IST)

#Angular13 #webdevelopment #learning #onlinetraining #education #software

[nareshitprasanna7]

👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar.

🛑 Free Demo 🛑 ✍️Enroll Now: https://bit.ly/3K77Rcb 👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar. 📅Demo On: 11th July @ 06:00 AM (IST)

#Angular13 #webdevelopment #learning #onlinetraining #education #software

[nareshitprasanna7]

👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar.

🛑 Free Demo 🛑 ✍️Enroll Now: https://bit.ly/3K77Rcb 👉Attend Free Online Demo On Angular 15 by Mr. Vijay Kumar. 📅Demo On: 11th July @ 06:00 AM (IST)

#Angular13 #webdevelopment #learning #onlinetraining #education #software

[codesolutionsstuff]

Dependency Injection in Angular with example

Angular is incredibly effective because it takes use of the Dependency Injection design pattern. Classes, components, and modules can interact while yet remaining consistent under this programming paradigm. As a result, the class changes less frequently. What is Dependency Injection? Dependency injection, a well-known programming concept, is what separates a class from its dependencies. Through the use of dependency injection, dependent objects can be created independently of classes and provided to classes in a variety of other ways. Think about the classes A and B. Assume class A makes use of class B's objects. A class B instance is typically generated in OOPS so that class A can access the objects. We use DI to remove the dependent objects' construction and binding from the class that depends on them. There are often three different categories of courses, namely: - Client Class - The dependent class on the service class is this one. - Service Class - Class that offers the client class the service. - Injector Class - Injects the object from the service class into the client class. Types of Dependency Injection in Angular In Angular, dependency injections come in three different types, and they are as follows: - Constructor injection: Through a class constructor, it gives the dependencies in this case. - Setter injection: The injector injects the dependence into a setter method that is used by the client. - Interface injection: Any client that is provided to the injector method by the dependence will receive the injection of the dependency. A setter method that accepts the dependence must be exposed through an interface that the clients must implement. Benefits of Dependency Injection - loosely coupled - Our Component is currently just loosely connected to the ProductService. The ProductService cannot be created by AppComponent. In reality, it has no knowledge of the ProductService. It only functions with the ProductService that was provided to it. ProductService, BetterProductService, or MockProductService are all acceptable options. The AppComponent is apathetic. - Easily Testable Testing AppComponent is now simpler. Our AppComponent is no longer reliant on a specific ProductService implementation. Any ProductService implementation that is provided to it will function. To pass during testing, simply create a mockProductService Class. - Reusing the Component: It gets simpler to reuse the component. With every ProductService moving forward, our Component will function as long as the interface is respected. Our AppComponent is now tested, maintainable, etc. thanks to the dependency injection technique. But does it fully resolve all of our issues? No, we simply transferred the Problem from the Component to the Component Creator. How can we make a ProductService object and send it to the AppComponent? Angular Dependency Injection accomplishes that. How DI (Dependency Injection) works Take into account the following service, which is produced by: ng g service test import { Injectable } from '@angular/core'; @Injectable({ providedIn: 'root' }) export class TestService { importantValue: number = 42; constructor() { } returnImportantValue() { return this.importantValue; } } As one can see, by including the @Injectable decorator in a class, we may construct injectable dependencies. We include the aforementioned dependent in the component shown below: import { TestService } from './../test.service'; import { Component, OnInit } from '@angular/core'; @Component({ selector: 'app-test', templateUrl: './test.component.html', styleUrls: }) export class TestComponent implements OnInit { value: number; constructor(private testService: TestService) { } ngOnInit() { this.value = this.testService.returnImportantValue(); } } At the top of the page, one can see that we have imported our TestService. The returnImportantValue function of the service was then implemented when we generated an instance inside the function Object() { } of the component. We can see from the aforementioned example how angular offers a fluid approach to inject dependencies in any component.

Conclusion

An excellent, multipurpose framework that accelerates development is Angular. It provides deep linking and dependency injection and is a reliable platform for software development. Read the full article

[codesolutionsstuff]

What is the difference between constructor and ngOnInit?

The Constructor, a default method of the class, is called when the class is instantiated and makes sure that the fields of the class and its subclasses are properly initialized. Dependency Injector (DI), or Angular, analyses the function constructor  parameters before trying to locate providers that match the types of the function constructor  parameters, resolving them, and passing them to the function constructor when it calls new MyClass() to build a new instance. When Angular is finished building the component, it calls the life cycle hook ngOnInit. Most of the time, we avoid doing anything in the function constructor  by using ngOnInit for all initialization and declaration. The only "work" that the function constructor  should perform is initializing class members. Therefore, you should only use function constructor  to set up Dependency Injection. Better to "start" from ngOnInit(), which is where/when component bindings are determined.

Example

// import OnInit import {Component, OnInit} from '@angular/core'; ... @Component({ ... }) // implementing OnInit export class AppComponent implements OnInit { constructor() { // constructor called first time before the ngOnInit() } ngOnInit() { // called after the constructor and called after the first ngOnChanges() } }

Difference between ngOnInit() and constructor()

- All initialization and declaration operations are performed using function constructor(). - Writing actual work in the function constructor() should be avoided. - The function constructor() should not perform any actual "work," merely initialize class members. - Therefore, to set up Dependency Injection, initialize class fields, etc., we should utilize the function constructor() method. - The "real work code" that must be run as soon as the class is instantiated should be put in ngOnInit(). - similar to loading database data to display to the user in your HTML template view. Such programming should be done in ngOnInit ().

Conclusion

- Initialize class members in the Constructor. - The functionality that has to run right away when the class is created should go in the ngOnInit() function. Read the full article

[codesolutionsstuff]

Angular Component Lifecycle Hooks Example

Angular's lifecycle hooks are a unique feature that lets us "hook into" and execute code at a particular component or directive lifecycle event. Angular applications go through a whole range of procedures or have a lifecycle from the moment they are created until they are terminated. When it adds, modifies, or deletes components and directives, Angular maintains them for us. With the help of lifecycle hooks, we may have more control over our application. To achieve this, we add a few certain hook methods to our component or directive that are prefixed with ng. Hooks for components or directives and hooks for child components are the two categories into which these hooks fall. The following will be covered in this article: - The many lifecycle hooks for Angular directives and components - How to run our code by hooking into component lifecycles - What activates lifecycle hooks, and how are they called in sequence? The following, in call sequence, are the hooks for components or directives: - constructor() - OnChanges - OnInit - DoCheck - OnDestroy The hooks for a component's child components are as follows: - AfterContentInit - AfterContentChecked - AfterViewInit - AfterViewChecked The table below provides a summary of the Angular lifecycle hooks: OnChangesThis method is invoked whenever the value of a data-bound property changes.OnInitThis is called each time the directive or component is initialized after Angular has shown the data-bound properties.DoCheckThis is to detect changes that Angular can't or won't notice on its own and to take appropriate action.OnDestroyJust before Angular kills the directive or component, this is the cleanup stage.AfterContentInitAfter Angular projects external material into the component's view, this is invoked in response.AfterContentCheckedAfter Angular has examined the content projected into the component, this is called as a response.AfterViewInitAfter Angular initializes the component's views and child views, this is invoked in response.AfterViewCheckedAfter Angular has checked the component's views and child views, this is invoked in response.Table - Angular Component Lifecycle Hooks OnChanges: Any time a data-bound property of an angular directive changes, this lifecycle hook is called. The Simple Changes object, which contains the current and historical data properties, is returned by this method. Because it continually triggers, make sure to restrict the quantity of processing. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements OnChanges { ngOnChanges(changes: SimpleChanges) { // code goes here... } } OnInit: During component initialization, this Angular lifecycle hook is immediately called. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements OnInit { ngOnInit() { // code goes here... } } DoCheck: In cases where Angular is unable to recognize the changes, this lifecycle hook is used in place of ngOnChanges. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements DoCheck { ngDoCheck() { // code goes here... } } OnDestroy : It is an important lifecycle hook that stops memory leak in Angular. When the component is destroyed, it starts to work. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements OnDestroy { ngOnDestroy() { // code goes here... } } AfterContentInit : After all of the content in a directive has been initialized by Angular, the callback function is initialized. And only one time, when the directive is called, is it called. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements AfterContentInit { ngAfterContentInit() { // code goes here... } } AfterContentChecked - Immediately following the directive content check, this lifecycle procedure is invoked. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements AfterContentChecked { ngAfterContentChecked() { // code goes here... } } AfterViewInit : The moment the component's view is created, this lifecycle method is called. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements AfterViewInit { ngAfterViewInit() { // code goes here... } } AfterViewChecked : Following the component's content check, this lifecycle function is invoked. @Component({ selector: 'ng-app', template: `...` }) class AppComponent implements AfterViewChecked { ngAfterViewChecked() { // code goes here... } }

Conclusion

Keep in mind that each hook has requirements that must be satisfied. Regardless, they will always carry out their actions one after the other. As a result, hooks are predictable enough to be used even when some of them do not work. Timing the execution of a class is simple with lifecycle hooks. They enable developers to monitor the location of change detection and the appropriate responses for the application. Code that needs load-based dependencies that become available only gradually causes them to stall. Modern front end frameworks are characterized by the component lifecycle. By offering the aforementioned hooks, Angular outlines its lifecycle. Read the full article

[codesolutionsstuff]

What is a template?

By connecting controls to Angular component properties, you may display data in a template, which is an HTML view. The template for your component can be kept in one of two locations. The @Component decorator's templateUrl property allows you to declare the template either inline using the template property or in a separate HTML file and link to it in the component metadata. Using inline template with template syntax, import { Component } from '@angular/core'; @Component ({ selector: 'my-app', template: '

{{title}}

Learn Angular ' }) export class AppComponent { title: string = 'Hello World'; } Using separate template file such as app.component.html import { Component } from '@angular/core'; @Component ({ selector: 'my-app', templateUrl: 'app/app.component.html' }) export class AppComponent { title: string = 'Hello World'; } I hope you will like the content and that it will help you to learn What is template? If you like this content, do share it. Read the full article