20 Expert Angular Interview Questions and Answers

 

Preparing for an interview? Like to understand the core concepts of Angular before appearing for an interview? Get the complete Q&A from Angular experts. Here is the ultimate list of top 20 Angular interview questions and answers you must know before appearing for an Angular interview.

 

1. Explain Data Binding In AngularJS? What Are The Types?

 

Data binding in Angular is the way to to define the communication between component and view which is very easy to define interactive applications without need of pulling or pushing data. The data binding in AngularJS allows you to treat the model as single source so whenever any changes occurs in model that will be directly projected in view.

 

  • String Interpolation
  • Property Binding

 

2. What Are Directives?

Directives are the ideal attributes which are responsible for transforming DOM behavior while rendering a template. Basically, built-in directives start with ng-prefix and some of the built-in directives has ngIf, ngFor.

 

You can write your own directives that suits your needs.

 

3. When Do You Use Template-Driven Vs Model-Driven Forms? Why?

 

As the name clearly states, Template driven form is something where we will indulge in writing logic, validation, controls everything in .html template file. Where as in model driven forms all the logic validation part in the controller side will be done in typescript file which is introduced to overcome the limitations of Template driven form.

 

4. What Are Expressions In Angular?

Expressions in AngularJS are used to bind the application data with HTML which will display the data from the model to view. Basically, Expressions will be written inside the double braces {{expression}} and we can also written it inside directive like: ng-bind=”expression”.

 

5. What Is Deep Linking In Angular?

Deep linking is a method of making the user to land in a specific page without taking them to the home page. This technique highly helps the pages to get indexed in search engines.

 

6. Explain ng-content, ng-container and ng- template?

Scope is a JavaScript object which is used to communicate controller and view. $scope binds & $rootscope is the parent or superior object of all scope objects in angular which is accessible everywhere from the application.

 

7. What Is Lazy Loading?

Lazy loading is a method that used to load JavaScript components asynchronously when a specific route is activated. This will be greatly helpful to boost the performance during initial load especially when you have complex routing with multiple components.

 

 

Check How To Use Lazy Loading In Angular Application To Increase The Website Speed

 

 

8. What Are Advanced Angular CLI Commands?

Some of the advanced Angular CLI commands.

 

Generate files in the angular application

ng generate component <your-component-name>

 

Compiling Angular application In Production

ng build –prod –aot

 

Run Unit Test Cases

ng test

 

Run automated test cases

ng e2e

 

Linting application:-

ng lint

 

 

Read More : Angular CLI Commands To Boost Your Productivity

 

 

9. What Is Angular Console?

Angular console is cross -platform desktop application, in which you can create projects and perform all the actions like commands, run generators,  install extensions, interacting with editor without getting a help of terminal.

10. What Is Pure Pipe & Impure Pipe?

Pure pipe is used when angular witnesses any change in value or when any parameters passed to pipe. Where as impure pipes will be called for every change detection cycle of components regardless of the value or parameter changes and eventually you can make pipes as impure pipes by setting a pure flag to false.

Some of the other advanced Angular Questions developers must know before appearing for an interview:

  1. What is the difference between a smart/container component and dumb/presentational component? What is a good use case? What are the advantages?
  2. How would you protect a component that is being activated through the router?
  3. When do you use template-driven vs model-driven forms? Why?
  4. What is the difference between a module’s forRoot() and forChild() methods?
  5. How would you implement a multiple api calls that needs to happen in order using rxjs?
  6. Can you explain the difference between ActivatedRoute and RouterState?
  7. What is the difference between ‘async()’ and ‘fakeAsync()’?
  8. Explain Object.freeze and possible use cases.
  9. What are the different compilation methods available in angular and what’s the difference between them?
  10. How would you create a component to display error messages throughout your application?

Related: Top 10 Angular Blogs You Must Read

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