100+ Angular Developer Interview Questions and Answers

Services are used to share data or functionality across components in Angular.

• Services are singleton objects that can be injected into components.

• They can be used to share data between components.

• They can also be used to encapsulate and share functionality.

• Examples include HTTP service for making API calls and logging service for tracking user actions.

Enhancing Angular app performance involves optimization techniques like lazy loading, change detection strategies, and efficient data handling.

• Use Lazy Loading: Load feature modules only when needed to reduce initial load time. Example: Implementing lazy loading in the routing module.

• Optimize Change Detection: Use OnPush strategy to limit checks to only when inputs change. Example: Using ChangeDetectionStrategy.OnPush in components.

• Track By in ngFor: Improve rendering perform...read more

Different looping constructs in programming serve unique purposes for iterating over collections.

• for: A traditional loop that iterates over a range of numbers. Example: for (let i = 0; i < 5; i++) { console.log(i); }

• for each: A method to iterate over elements in an array or collection. Example: array.forEach(item => console.log(item));

• for of: A modern loop for iterating over iterable objects like arrays, strings, etc. Example: for (const item of array) { console.log(item); }

Switched to Angular for its robustness and scalability.

• Angular offers better performance and scalability compared to other frameworks.

• Angular's modular architecture allows for easy maintenance and updates.

• Angular's extensive documentation and community support make it a reliable choice.

• Switching to Angular also allowed for better integration with other technologies.

• Overall, the decision to switch to Angular was based on its ability to meet our project's needs and future growt...read more

Follow best practices in Angular to enhance code quality, maintainability, and performance.

• Use Angular CLI for project setup and management to ensure consistency.

• Organize code into modules for better separation of concerns.

• Implement lazy loading for feature modules to improve application performance.

• Utilize services for data management and business logic, keeping components lean.

• Follow the Angular style guide for naming conventions and file structure.

• Use reactive programming ...read more

A palindrome is a string that reads the same forwards and backwards. Here's how to check for it in JavaScript.

• Convert the string to lowercase to ensure case insensitivity. Example: 'Racecar' becomes 'racecar'.

• Remove non-alphanumeric characters to focus only on letters and numbers. Example: 'A man, a plan, a canal: Panama!' becomes 'amanaplanacanalpanama'.

• Reverse the cleaned string and compare it to the original cleaned string. If they match, it's a palindrome.

• Example function...read more

call, apply, and bind are methods to set the context of 'this' in JavaScript functions.

• call: Invokes a function with a specified 'this' value and arguments provided individually. Example: func.call(obj, arg1, arg2);

• apply: Similar to call, but arguments are provided as an array. Example: func.apply(obj, [arg1, arg2]);

• bind: Returns a new function with a specified 'this' value, allowing for later invocation. Example: const boundFunc = func.bind(obj);

Different ways to pass data from one component to other components in Angular.

• Input bindings

• Output bindings

• ViewChild

• Services

• Event emitters

Components and directives are key building blocks of Angular applications.

• Components are reusable UI elements that encapsulate logic and data.

• Directives are instructions in the DOM that modify its behavior.

• Types of directives include structural, attribute, and component.

• Structural directives modify the DOM layout, attribute directives modify element behavior, and component directives create new components.

• Examples of built-in directives include ngIf, ngFor, and ngStyle.

Web workers are JavaScript scripts that run in the background, separate from the main browser thread.

• Web workers allow for parallel execution of tasks, improving performance and responsiveness.

• They can perform computationally intensive tasks without blocking the user interface.

• Web workers communicate with the main thread using message passing.

• Examples of tasks suitable for web workers include data processing, image manipulation, and complex calculations.

ActivatedRoute is used to access the current route's information.

• It provides access to route parameters, query parameters, and fragment parameters.

• It can be used to subscribe to route parameter changes.

• It can be injected into a component or service.

• Example: accessing a route parameter in a component using snapshot: this.route.snapshot.params['id']

• Example: subscribing to route parameter changes in a component: this.route.params.subscribe(params => console.log(params))

Code for sorting an array in ascending order without any sort functions.

• Use nested loops to compare each element with every other element in the array.

• Swap the elements if they are not in the correct order.

• Repeat the process until the array is sorted in ascending order.

Components are building blocks of Angular applications. Data can be shared between components using input/output properties, services, or state management. Pipes are used for data transformation in templates.

• Components are reusable, self-contained units of code that define the view and behavior of a part of the application.

• Data can be shared between components using @Input and @Output properties for parent-child communication, services for cross-component communication, or st...read more

Using a shared service to communicate data between unrelated components in Angular.

• Create a shared service with a BehaviorSubject to store and emit data

• Inject the shared service into both components that need to share data

• Subscribe to the BehaviorSubject in each component to receive updates

NodeJS is a runtime environment that allows you to run JavaScript on the server side.

• NodeJS is built on Chrome's V8 JavaScript engine.

• It uses an event-driven, non-blocking I/O model.

• NodeJS is commonly used for building server-side applications and APIs.

• npm (Node Package Manager) is used for managing dependencies in NodeJS projects.

Map, filter, and reduce are array methods in JavaScript for transforming and processing data.

• Map: Creates a new array by applying a function to each element. Example: [1, 2, 3].map(x => x * 2) results in [2, 4, 6].

• Filter: Creates a new array with elements that pass a test. Example: [1, 2, 3].filter(x => x > 1) results in [2, 3].

• Reduce: Reduces an array to a single value by applying a function. Example: [1, 2, 3].reduce((acc, x) => acc + x, 0) results in 6.

API to send data to a specific endpoint using any language

• Choose a programming language that supports HTTP requests

• Create a function to send data to the endpoint using HTTP POST method

• Include necessary headers and parameters in the request

• Handle any errors or exceptions that may occur

Services in Angular are singleton objects that can be injected into components, directives, and other services.

• Services are used to encapsulate reusable functionality, such as data fetching, logging, or authentication.

• They are defined using the @Injectable decorator and can be injected into components using dependency injection.

• Services help in keeping the code modular, maintainable, and testable.

• Example: A UserService that handles user authentication and data fetching.

• Direct...read more

Components are used to create reusable UI elements with a template, while directives are used to add behavior to existing elements.

• Components have a template, while directives do not.

• Components are used to create reusable UI elements, while directives are used to add behavior to existing elements.

• Components have their own view encapsulation, while directives do not.

• Components can have their own styles, while directives do not.

• Components can have their own lifecycle hooks, whi...read more

Services, modules, decorators, and directives are key concepts in Angular development.

• Services: Reusable code that can be injected into components to provide specific functionality.

• Modules: Containers for different parts of an Angular application, including components, services, and directives.

• Decorators: Functions that modify classes or properties in Angular, used for adding metadata or behavior to components.

• Directives: Extend HTML with custom attributes and elements, allow...read more

Manage security in Angular by using built-in features, best practices, and regular updates to mitigate vulnerabilities.

• Use Angular's built-in security features like DomSanitizer to prevent XSS attacks.

• Implement Content Security Policy (CSP) to restrict resources that can be loaded.

• Regularly update Angular and its dependencies to patch known vulnerabilities.

• Validate and sanitize user inputs to prevent injection attacks.

• Use Angular's HttpClient with proper headers to prevent CS...read more

ngShow toggles visibility with CSS, while ngIf adds/removes elements from the DOM based on a condition.

• ngShow: Uses CSS display property to show/hide elements without removing them from the DOM.

• Example: <div ng-show='isVisible'>Content</div> - Content remains in DOM but hidden if isVisible is false.

• ngIf: Conditionally includes or excludes elements from the DOM based on the expression's truthiness.

• Example: <div ng-if='isVisible'>Content</div> - Content is added to the DOM only...read more

Angular is a complete framework while React is a library for building UI components.

• Angular is a complete framework with built-in features like routing, forms, and animations.

• React is a library for building UI components and requires additional libraries for features like routing and forms.

• Angular uses two-way data binding while React uses one-way data flow.

• Angular has a steeper learning curve while React is easier to learn.

• Angular is maintained by Google while React is maint...read more

Angular application bootstraps by loading the root module and then creating the component tree.

• Angular application bootstraps by loading the root module, which is defined in the 'AppModule' class.

• The 'AppModule' class contains metadata such as the list of components, directives, and services used in the application.

• After loading the root module, Angular creates the component tree by instantiating the root component specified in the 'AppModule' class.

• The root component then bo...read more

Software development life cycle (SDLC) is a process used to design, develop, and maintain software.

• SDLC consists of several phases: requirements gathering, design, development, testing, deployment, and maintenance.

• Each phase has specific activities and deliverables.

• SDLC models include Waterfall, Agile, and DevOps.

• Waterfall follows a sequential approach, while Agile and DevOps are iterative and involve continuous feedback and improvement.

• SDLC ensures efficient and quality soft...read more

Javascript subjects are observables that can multicast to many observers, while BehaviorSubject is a type of subject that stores the latest value and emits it to new subscribers.

• Subjects in Javascript are observables that can multicast to many observers

• BehaviorSubject is a type of subject that stores the latest value and emits it to new subscribers

• Example: const subject = new Subject(); const behaviorSubject = new BehaviorSubject('initial value');

Data binding is a way to connect data between the component and the view in Angular.

• Data binding allows for automatic synchronization of data between the component and the view.

• There are three types of data binding in Angular: Interpolation, Property binding, and Event binding.

• Interpolation is used to display component data in the view using double curly braces {{}}.

• Property binding is used to set the value of an element property to a component property using square brackets ...read more