AngularJS Interview Questions and Answers

AngularJS, the self-described “superheroic JavaScript MVW framework,” has been around since 2009 and is still one of the most widely used web development frameworks. One of the most interesting languages is AngularJS. This technology, with its extensive feature set, is well worth the effort.

AngularJS is a demanding technology, with salaries ranging from $60 per hour for a freelancer to $70,000 per year for a Front End Developer/Engineer in a company. You can anticipate that there will never be a shortage of qualified people because this certification is required for a high percentage of web-developer job advertising. To be able to crack the AngularJS interview questions, one needs to have in-depth knowledge about AngularJS. The important AngularJS interview questions and answers, along with detailed information on the preparation, have been listed below.

 ANGULARJS INTERVIEW QUESTIONS AND ANSWERS

The following is a comprehensive list of AngularJS interview questions and answers. Beginner, intermediate, and advanced questions have been grouped into three tiers.

BEGINNERS

A junior developer is someone who is new to the industry and has less than two years of experience. Because junior AngularJS engineers require tight supervision from more experienced AngularJS developers, they are frequently employed as part of a team. Their primary responsibility is to do assignments that are then double-checked.

• Junior AngularJS Developers’ Skill Requirements
• Basic HTML, CSS, and Javascript skills
• Foundational AngularJS knowledge
• Learning on the job
• Following instructions and receiving feedback
• Thinking like a programmer

BASIC AngularJS INTERVIEW QUESTIONS AND ANSWERS

1. What is the ForEach loop’s syntax? Which of the following loops would you use to parse a JSON file, and why?

This is a commonly asked AngularJS interview question. The syntax for each loop is as follows:

angular.ForEach(students,function(value,key)

We can use any loop to parse JSON, but I use it for each because it reduces my code by eliminating the requirement to keep the length of a JSON in a variable.

2. Can you explain MVC in terms of Angular?

This is an important AngularJS interview question. The model for a controller contains data, the controller for a view has the logic to manipulate that data, and the view is the that shows the data in AngularJS.

A $scope can be thought of as a model, with angular controller functions changing the $scope and HTML displaying the value of the scope variable.

3. What is the definition of two-way binding?

When data in the view is changed, the underlying model is automatically updated, and when a model from the controller is modified, the view is automatically updated.

4. Can a single angular application have two ng-apps?

This is a commonly asked AngularJS interview question. No, a single AngularJS application cannot have more than one ng-app.

The ng-app directive indicates that the AngularJS application is the root element. You can only have one ng-app directive in your HTML content. If there are several ng-app directives, the first one will be used.

5.What exactly is $scope?

$scope is a controller model that aids the controller’s interaction with the view.

This is a very brief response to this question, but it is comprehensive in every way. Attempt to avoid using any additional angular words.

6. What are a few examples of built-in angular filters?

A few inbuilt angular filters are currency, lowercase, uppercase, number, and date.

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INTERMEDIATE AngularJS QUESTIONS AND ANSWERS

Let’s have a look at some AngularJS interview questions for mid-level developers.

7. What are custom filters, and how can I use them?

We can construct our filters with AngularJS. This is accomplished by linking the filter to our module. Custom filters are the name for these types of filters.

8. What is the difference between ng-if and ng-show?

This is a commonly asked AngularJS interview question. If the stated condition is not met, ng-if does not render the piece of the DOM element with which it is related, whereas ng-show renders the DOM element. However, it places its CSS property of display to none if the particular condition is not met.

9. What is the $watch’s purpose?

The objective of $watch is to keep track of the monitored expression’s old and new values.

10. What is $rootScope’s purpose?

This is an important AngularJS interview question. $rootScope facilitates communication between an application’s many controllers. An app can only have one rootScope in AngularJS.

11. In AngularJS, what are expressions?

In AngularJS, expressions are code snippets that translate to a value. AngularJS expressions are contained within the expression tag. HTML elements have expressions built-in.AngularJS expressions, like JavaScript expressions, can contain a variety of valid expressions.

12. When visiting a server method, where should form action be used instead of $http?

Form action should be used when the server-side method redirects the user to another view, whereas HTTP requests should be used when the server method returns data.

13. What do you mean by Data binding in AngularJS?

This is a commonly asked AngularJS interview question. The synchronizations of data between view components and the model is known as data binding. Hence there are 2 different types of Data binding;

• Binding of Data in Angular templates.
• Mining of data in a classical template system.

14. What is the purpose of ng-init?

Ng-init is used in situations where we wish to do an action before the initialization of a DOM element.

15. Is it possible to set an angular variable from a PHP session variable without having to make an HTTP request?

Yes, we may do so by injecting PHP in the appropriate location.

16. What is the purpose of the pipe operator in AngularJS?

In AngularJS, the pipe operator represents filters that are applied to the expression. The order of preference is from left to right. SOMEVALUE would be the outcome of the above expression.

17. Is JQuery required for AngularJS?

This is an important AngularJS interview question. Models, directives, two-way binding, routing, unit tests, dependency injections, and other features distinguish AngularJS from other JavaScript frameworks. JQuery, on the other hand, is a JavaScript library for DOM manipulation that does not support two-way binding.

18. What is the purpose of the service in AngularJS?

In AngularJS, services are also objects that are used to interact between different parts of an application.

19. What exactly is dependency injection, and what are the advantages?

This is an important AngularJS interview question. Dependency injection is a strong design pattern that separates the concerns of distinct components in an application and allows the dependent component to be injected into the client component.

20. In AngularJS, what are controllers?

Controllers are JavaScript functions that provide data and logic to HTML user interfaces. It serves as a link between the server and the HTML user interface. $scope is a parameter that each controller accepts, and it refers to the application/module that the controller will govern.

21. Is it possible for the parent controller to access the methods of the child controller and vice versa?

No, the parent controller cannot access the child controller’s methods, but the child controller can access the parent controller’s methods.

22. Is it possible to utilize the ternary operator in an angular expression?

This is a commonly asked AngularJS interview question. In an angular expression, ternary operators or no flow operators can be employed.

23. When does $location come into play? Explain with an example.

$location is an Angular service that stores the application’s URL and makes it available to a controller. The impact of changing $location from the controller is mirrored in the address bar and vice versa.

ADVANCED AngularJS INTERVIEW QUESTIONS AND ANSWERS

An excellent AngularJS developer must be well-versed in the AngularJS framework. Ideal applicants will be able to create effective applications, write clean and robust code, collaborate effectively with others, and pass on their knowledge to junior engineers.

• Senior AngularJS Developer Requirements
• Expert AngularJS understanding
• MVC Design Pattern
• Designing to meet specific needs (e.g. security, scalability, optimization)
• Programming in the asynchronous mode
• Updating and maintaining applications
• You have experience with the frameworks, toolkits, and libraries you use.
• Clean code and efficient programming
• Debugging
• Unit and end-to-end testing
• Ability to lead
• Ability to communicate clearly
• Guiding less experienced developers

24. In ng-repeat, what is the function of the track?

Directives like ng-repeat in AngularJS keep track of all the items to reduce DOM generation. When a new element is added to the collection, it does so by storing the object instance. Angular does not re-render the full element set; only the new element is rendered.

When using ng-repeats with an object that has a unique identifier, the tracking should be done by that identification rather than the object instance.

The item id is used to track the items.

25. What distinguishes the scope of a directive from the scope of a controller?

This is an important AngularJS interview question. The scope object has two instances: $scope and scope. The distinction is in the names given to them. To understand the distinction between $scope and scope, we must first understand isolated scope directives.

A directive with an isolated scope is declared in the code above. A normal Javascript function with signature scope, element, and attribute is utilized in the preceding code. The name of the scope object is unimportant because it will be linked to the directive’s scope object regardless of the name you give it. As a result, using myScopeVar will not result in an error. On the other hand, the $scope can’t be used with any other name.

26. In AngularJS, what do you mean by Dependency Injection?

This is an important AngularJS interview question. One of the best aspects of AngularJS is Dependency Injection (commonly known as DI). It’s a software design pattern in which items are supplied as dependencies instead of being hard-coded within the component. It can be used to replace hard-coded dependencies with adjustable dependencies. It lets various components in an application have their concerns separated and provides a means to inject the dependent component into the client component. We can make components maintainable, reusable, and testable by using Dependency Injection.

27. What’s the difference is between compile and link.

Compile can basically be thought of as a service that scans HTML, searches for all directives, and produces a link function.
By contrast, Link mixes the model and a view. If there is a change in the model, it would reflect a change in the view, and the model reflects the change in the view.

28. What does strict conceptual escape entail?

This is an important AngularJS interview question. In HTML or sensitive URL bindings, AngularJS defaults to treating all values as untrusted/unsecured. When binding untrusted values, AngularJS will perform security checks on them (sanitizations, whitelists, etc.) or issue an exception if the result cannot be guaranteed to be secure.

Consider the ng-bind-html directive as an example. It directly renders its value as HTML. If a sanitizer is provided, AngularJS will try to sanitize an untrusted input before rendering it. You must declare the input as trusted to bypass sanitization and render it as-is.

29. In AngularJS, how are logs kept?

The next question would be how to Blackbox AngularJS source in the browser, as well as whether browsers support Blackbox.
The $log service is used to keep track of logs. This service’s primary goal is to assist with debugging and troubleshooting.

Four ways are used to do this.

1. log() – creates a console log message.
2. info() generates a message of information.
3. create a warning message with warn()
4. error() is a function that generates an error message.
5. debug() is a function that generates a debug message.

30. In AngularJS, what are templates? Give an example of code.

This is an important AngularJS interview question because the knowledge of AngularJS and the MVC Design Pattern is required.

The HTML portion of an AngularJS app is called templates. They are HTML documents with AngularJS-specific elements and properties. To display the dynamic view that a user sees in the browser, AngularJS combines the template with information from the model and controller. It allows you to inject data into an HTML page.

• A directive is an element or attribute that extends the functionality of an existing DOM element or symbolises a reusable DOM component.
• AngularJS markup has the double curly brace notation for binding expressions to elements.
• Filter — Formats data to make it easier to read.
• Validates user input using form controls.

Some Interesting Facts about AngularJS

1. AngularJS is a Google-developed open-source JavaScript framework. All of the interactive components that we usually see on a website may be produced with AngularJS. The framework’s major goal is to help in the development of single-page applications. Web developers favor AngularJS over other frameworks because it prioritizes code quality and testability.
2. AngularJS is easy to learn if you know HTML, CSS etc. A number of opportunities are available if one were to learn Angular JS. There are numerous free AngularJS tutorials and courses available online. These free tutorials will teach you how to use AngularJS to design and test your web application.
3. The model and the view can be synchronized instantly with AngularJS. Any variations to the model’s data are shown in the display. When the view data changes, the model is updated to reflect the changes. The application’s display layer will be greatly simplified because of this two-way data coupling. This provides for a more straightforward, less intrusive approach to DOM display.
4. Creating single-page applications is mostly motivated by the desire to make website transitions go more quickly. The functionality and design of the website will be identical to that of a native app. A website will communicate with the web browser by dynamically altering the existing web page with new Web server data, rather than the browser’s usual method of loading entirely new pages. When a programmer makes use of AngularJS to produce a single page application, the page loads rapidly, is cross-platform compatible, gives a good user experience, and is much easier to maintain.
5. The AngularJS framework uses HTML to construct templates. Because of its inherent intuitiveness and scalability, it is a widely used declarative language. Filters, directives like ng-repeat, ng-app, form controls, ng-model, and other AngularJS-specific components and attributes are included in templates.
6. The usage of a declarative user interface makes things easier to understand and control. HTML allows developers and designers to collaborate. Designers can focus on building UI while developers utilize declarative binding vocabulary to connect various UI components with data models.
7. AngularJS is an open-source front-end framework written in JavaScript that is mostly used to create single-page web applications (SPAs). AngularJS adds additional attributes to HTML. Single Page Applications are ideal for AngularJS (SPAs). AngularJS is a simple framework to learn. Learning AngularJS provides a plethora of opportunities for people.
8. Google’s apps are built with the AngularJS framework. Additional improvements to the AngularJS framework have been developed by Google engineers. Many developers prefer AngularJS to other frameworks. The language has gained credibility as a result of Google’s backing. The large developer community is another advantage of AngularJS. You may rapidly get help from other programmers.
9. Another benefit of AngularJS is that it provides a robust front-end development solution. A few of the features are MVC design, directives, and dependency injection. It is popular among developers because it is free. This can be used by developers to extend HTML syntax and build client-side applications.
10. The design goals of AngularJS are as follows:
    • to separate application logic from DOM manipulation The structure of the code has a significant impact on the complexity of this.
    • To separate the client and server sides of an application allows development to proceed in parallel while allowing both sides to be reused.
11. Declarative programming should be used to connect software components and construct user interfaces, whereas imperative programming is better fitted to define an application’s business logic, according to AngularJS. The framework has adapted and extended traditional HTML to show dynamic content through two-way data binding, which allows models and views to automatically synchronise.
12. Miko Hevery at Brat Tech LLC created AngularJS in 2009 as the software behind an online JSON storage service that would have been charged by the megabyte for easy-to-make enterprise apps. This venture had a few subscribers and was located at the web domain “GetAngular.com ” before the two decided to forgo the business idea and distribute Angular as open source.
13. Material Design is implemented in AngularJS through AngularJS Material, a UI component library. The library includes a collection of UI components that are reusable, well-tested, and easy to use.

Job description for an AngularJS developer

Client-side programming for online and cross-platform mobile apps is expected of an AngularJS developer. A user interface design should be able to be implemented by the developer.

An AngularJS programmer should be able to construct and combine modules and components to produce a working app. The developer and the server-side developer should collaborate closely.

Roles and duties of an AngularJS developer

The following tasks and duties should be able to be fulfilled by an AngularJS developer:

• Business analysts (BAs) can help you understand the project needs.
• Taking the architect’s advice into consideration when studying the technical solution and architectural pattern;
• Creating program and component specs;
• Developing new AngularJS applications on the client-side;
• Integrating the front-end with the backend to enable proper application data processing;
• Unit testing as well as taking part in the overall testing effort;
• Collaboration with the bigger team, which includes BAs, PMs, developers, testers, and DevOps engineers;
• Reporting on the current state of the job.

As an AngularJS developer, you’ll require the following skills and abilities.

1. Compilation is one of the core AngularJS skills.

AngularJS is a complex framework. The following skills are required of AngularJS programmers:

• Knowledge of scope objects and the AngularJS scope model in depth;
• Strong understanding of HTML, HTML5, CSS, and CSS3;
• AngularJS APIs are well-versed;
• Good knowledge of the AngularJS compiler;
• The ability to use the AngularJS div;
• The ability to employ AngularJS functionalities like lowercase and uppercase;
• AngularJS syntax is well-versed;
• The config method’s usage experience;
• A thorough understanding of the AngularJS function Object() function;
• In-depth knowledge of how to initialize Dada during the development process;
• Deep understanding of AngularJS modules such as myApp;
• Knowledge of the AngularJS link function is required.
• Knowledge of AngularJS attributes such as nextSibling;
• Good understanding of the AngularJS method angular.module;
• Excellent grasp of reusable components and AngularJS directives;
• strong knowledge of TypeScript.

2. The ability to use AngularJS APIs such as “compile.”

$compile, for example, is a handy API in AngularJS. Developers can accomplish a lot with these APIs, so look for AngularJS developers who know how to use them. Other APIs, such as “root element,” “orderby,” and so on, are also useful.

3. Knowledge of well-known libraries such as jQuery

They require an AngularJS developer who is well-versed in JavaScript. This involves understanding JavaScript objects, JSON, and so on. Popular libraries such as jQuery should be recognizable to experienced AngularJS developers.

4. JavaScript expressions are a must-have skill.

AngularJS developers should be well-versed in JavaScript expressions. Because AngularJS expressions are comparable to JavaScript expressions, knowing this will benefit the developer significantly.

5. Experience in backend development

• a thorough understanding of common architectural patterns;
• Knowledge of cloud computing systems such as AWS, Microsoft Azure, and Google Cloud Platform;
• SQL expertise is extensive;
• RDBMSs (relational database management systems) such as MySQL, PostgreSQL, and others;
• Knowledge of NoSQL databases such as MongoDB, Cassandra, and others;
• Experience designing scalable web apps;
• understanding of developing RESTful APIs;
• knowledge of managing application security issues.

6. Skills in software engineering

• Knowledge of popular development techniques such as Agile;
• Skills in code review;
• Methods and strategies for preventing software defects;
• Good understanding of unit testing, system testing, performance testing, and other related topics;
• DevOps methodology, processes, tools, and practices are well-understood.

7. Competencies required of an AngularJS developer

• Developing a web or cross-platform mobile application that provides a good user experience can be challenging. You must have a passion for excellence that allows you to think like end-users.
• Commitment
• Problem-solving: abilities show that you can solve problems effectively. Several abstractions are used in software development projects. Success necessitates the ability to prioritize, brainstorm, think analytically, and solve problems in general.
• Communication abilities: An efficient AngularJS developer must be able to communicate with all key parties. Communication with testers, BAs, DevOps engineers, and others should be regular and meaningful. Good communication skills are necessary.
• Collaboration: Without teamwork, it’s difficult to succeed. Collaboration is required for teamwork.
• To be able to see the bigger picture.

Tips on how to prepare

• Reading and understanding the official Developer Guide is a better method to prepare for an AngularJS interview.
• Examine performance concerns and potential solutions.
• On GitHub, have a look at some of the most popular boilerplates.
• Take a peek at some of the StyleGuides produced by influencers.

First and foremost, you must study the Official Developer Guide, which is devoid of any extraneous material. It’s a quick read with a lot of knowledge.

Read it from beginning to end.

Data binding, controllers, directives (components), services, scope, dependency injection, and templates are just a few of the key concepts covered there.

Every sentence and statement in that handbook should be understood.

AngularJS developers should be familiar with bootstrap development, factory methods, and other similar concepts. Many AngularJS application development projects are complicated. Developers will be more effective if they have a thorough understanding of this development framework.

AngularJS developers can benefit greatly from a thorough understanding of directives like ng-repeat, ng-app, ng-show, ng-init, ng-bind, ng-hide, ng-controller, and others. With this understanding, programmers may more easily develop various functionality. They can easily create a custom directive.

When hiring AngularJS developers, look for interpolation, validation, injector, and other abilities. Interpolation, for example, allows developers to incorporate expressions within the marked-up text. AngularJS’ understanding of client-side form validation is beneficial to programmers.

Advantages

Angular Features’ Business Advantages:

• Cross-Platform Development that Works
• The application is of excellent quality.
• Improved performance and speed.
• Streamlining the development process.
• Code that is both readable and testable.
• More Web Apps That Aren’t Heavy.
• Problem-Solving Patterns That Work.
• The Material Design Library is fantastic.

Popularity

Angular’s popularity stems from the fact that it allows for secure data binding to HTML components. The Angular directives investigated a method for creating HTML+CSS modular components. This was the first JavaScript framework to achieve significant prominence over the others.

Digest loop or Digest circle

You should be aware of how the digest circle functions. Understanding the dirty check is essential for preventing performance issues in AngularJS-based applications.

Investigate the following question using the Internet and reference books.

• What are the functions $watch(), $digest(), and $apply()?
• Who starts the digestion process, and when does it happen automatically?
• How could it be manually triggered?
• Why might $digest cause performance issues?

Dependency Injection

You should be familiar with the theory behind the Dependency Injection approach, as well as some best practices for implementing it using JavaScript.

Understand why we have a namespacing problem in JS minification and how to fix it with annotation.

There are two forms of annotations, and $inject property annotation is preferred since it may be automated.

• Gulp-ng-annotate — Automatic Annotation Gulp
• babel-plugin-AngularJS-annotate (Webpack)

You should be aware of the distinctions between services, factories, and other types of service providers.

A mechanic of DI

Providers are defined with $provide.

• $provide exposes the methods provider, service, constant, value, and factory to the module object. Retrieve object instances with $injector.
• Controller, directive, and filter are all terms that can be used to describe how something works. Because $injector.invoke invokes $injector.invoke, we can easily obtain dependencies.

Performance

Any developer may quickly design an application using AngularJS. Unfortunately, if you have a low-quality staff, you may find yourself in a performance bottleneck.

The fundamentals of JS optimization state that it is preferable to:

• Whenever possible, avoid making calls in a loop.
• DOM modification should be avoided.

We can change it to:

• Minimize $$watchers array and control digest cycle, which is related to AngularJS.
• ng-repeat should not be refreshed. When working with a large array, avoid using filters.

Modern approaches

AngularJS is far from being a cutting-edge framework. However, there are still ways to get around AngularJS’s harsh realities.
Take a peek at some boilerplates made with WebPack, ES6, and TypeScript.

The typical instructions in the AngularJS Guide are not adequate for these instances, although style guidelines based on ES6 are well defined.

Style Guides

Style guidelines are a very important knowledge repository for AngularJS real-world use cases and solutions. “AngularJS style guide by John Papa ” and “AngularJS style guide (ES2015) by toddmotto” are the most popular style guides.

Summary

You can also check over any previous tasks you’ve done with the subject and make sure you’re comfortable speaking about them. If you are a fresher, the interviewer does not expect you to answer complex AngularJS interview questions; instead, you must strengthen your fundamental concepts.

• This method does not guarantee that you will pass all AngularJS interview questions; there are too many traps and hacks in AngularJS that require extensive familiarity with it.
• These AngularJS interview questions and answers are the ones that are most frequently asked.
• A good company is more interested in your broad skills in JavaScript, Front-End Development, and, eventually, engineering than in specialized Framework or library knowledge.
• Lastly, it doesn’t matter if you can’t answer a few questions; what matters is that whatever you respond is with utmost confidence.

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