Angular 5 years experience interview questions

Here are some interview questions for candidates with around five years of experience in Angular, along with their answers:

1. Can you explain the concept of Angular Ivy and its benefits?

   • Angular Ivy is the new rendering engine introduced in Angular version 9. It provides several benefits, including:
     • Faster compilation times
     • Smaller bundle sizes
     • Improved debugging and error messages
     • Enhanced template type checking
     • Better performance and runtime efficiency
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2. What is the Angular change detection mechanism and how does it work?

   • Angular's change detection mechanism is responsible for detecting changes in the component's data and updating the user interface accordingly. It works by comparing the previous and current values of the component's properties and triggers a re-rendering of the affected parts of the UI. Angular uses Zone.js and the concept of change detection tree to efficiently track and update changes.
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3. What are Angular directives? Explain the difference between structural and attribute directives.

   • Directives are markers on DOM elements that instruct Angular to perform specific behavior or apply transformations. Structural directives modify the structure of the DOM, such as *ngFor and *ngIf, by adding or removing elements based on conditions. Attribute directives change the behavior or appearance of an element, such as ngStyle or ngClass, by manipulating the element's attributes.
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4. How would you optimize the performance of an Angular application?

   • There are several techniques to optimize the performance of an Angular application, such as:
     • Minifying and bundling the application's code
     • Implementing lazy loading to load modules and components on demand
     • Using AOT (Ahead-of-Time) compilation to reduce the bundle size
     • Implementing efficient change detection strategies (OnPush)
     • Using trackBy function with ngFor for better list rendering performance
     • Optimizing API calls by using caching, pagination, or debounce
     • Employing lazy loading and code splitting for optimal loading times
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5. Explain the concept of Angular forms. What are the different types of forms available in Angular?

   • Angular forms provide a way to capture and validate user input. There are two types of forms in Angular:
     • Template-driven forms: They rely on Angular directives and two-way data binding to handle form data and validation. These forms are easier to set up and suitable for simple scenarios.
     • Reactive forms: They are built using ReactiveFormModule and allow for a more reactive and predictable approach. Reactive forms are suitable for complex scenarios and provide better control over form validation and data handling.
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6. How would you handle cross-origin requests (CORS) in Angular?

   • Cross-origin requests can be handled in Angular by configuring the backend server to allow requests from specific domains. Additionally, Angular provides the HttpClientModule, which automatically sends the required CORS headers with every request. You can also configure proxy settings in the Angular CLI to avoid CORS issues during development.
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7. Explain the concept of Angular services and how they can be shared across components.

   • Angular services are singleton instances that provide a way to share data, state, or functionality across multiple components or modules. Services can be injected into components, other services, or directives using Angular's dependency injection mechanism. By providing services at the root level or using hierarchical injectors, they can be shared and accessed by multiple components throughout the application.
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8. How would you handle routing and navigation in Angular?

   • Angular provides a powerful router module for handling routing and navigation. To set up routing, you define routes in the app-routing.module.ts file, specifying the path, component, and any additional configuration. You can navigate between routes programmatically using the Router service or by using the routerLink directive in HTML templates.
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9. What are Angular decorators and how are they used in Angular applications?

   • Decorators are a feature of TypeScript used in Angular to modify the behavior of classes, properties, methods, or parameters. They are defined using the @ symbol followed by the decorator name. Angular decorators, such as @Component, @Injectable, and @Input, are used to annotate and configure Angular components, services, and directives.
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10. How would you handle asynchronous operations in Angular?

    • In Angular, you can handle asynchronous operations using techniques such as Promises, Observables, or async/await with RxJS. Promises can be used for simple asynchronous tasks, while Observables provide more powerful features like handling multiple values over time, cancellation, and error handling. RxJS operators can be used to transform, filter, or combine Observables.