Top 15+ Angular Interview Questions and Answers for 2023

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1. What is the option to choose between inline and external template?

Usually, inline templates are used for small codes and external templates are used for comparatively bigger views. However, the choice of inline or external templates is sometimes based on organization policy, situations etc.

2. What is the purpose of ngFor directive?

Whenever it is required to repeat a part or portion of an HTML template once for each item from a collection, the ngFor directive is used. Basically it creates a template for each time as the iteration becomes easier using ngFor directive.

3. What is the purpose of the ngIf directive?

The purpose of the ngIf directive is to remove or recreate a part of DOM tree in alignment to an expression. If the ngIf directive finds that the expression is evaluating to be false, the element is removed from the tree, else a matching element is inserted into the DOM tree.

4. What are custom elements?

A custom element is used to extend HTML, wherein you can define a tag whose content is created and controlled by JavaScript code.

5. Do I need to bootstrap custom elements?

No, you do not need to bootstrap custom elements as they bootstrap automatically when added to the DOM. Also, the custom elements in Angular get automatically destroyed when removed from the DOM.

6. How do you chain pipes?

The syntax used for chaining pipes in Angular is given in the following example:

Today is {{ today | date:’fullDate’ | uppercase}}.

7. What are Angular expressions?

Angular expressions are code snippets that are usually placed in binding such as {{ expression }} similar to JavaScript. These expressions are used to bind application data to HTML

Syntax: {{ expression }}

8. What are directives in Angular?

A core feature of Angular, directives are attributes that allow you to write new HTML syntax, specific to your application. They are essentially functions that execute when the Angular compiler finds them in the DOM.  The Angular directives are segregated into 3 parts:

  1. Component Directives
  2. Structural Directives
  3. Attribute Directives

9. What is data binding?

In Angular, data binding is one of the most powerful and important features that allow you to define the communication between the component and DOM(Document Object Model). It basically simplifies the process of defining interactive applications without having to worry about pushing and pulling data between your view or template and component. In Angular, there are four forms of data binding:

  1.  String Interpolation
  2. Property Binding
  3. Event Binding
  4. Two-Way Data Binding

10. Does Angular support nested controllers?

Yes, Angular does support the concept of nested controllers. The nested controllers are needed to be defined in a hierarchical manner for using it in the View.

11. What is the difference between a service() and a factory()?

A service() in Angular is a function that is used for the business layer of the application. It operates as a constructor function and is invoked once at the runtime using the ‘new’ keyword. Whereas factory() is a function which works similar to the service() but is much more powerful and flexible. factory() are design patterns which help in creating Objects.

12. Explain jQLite.

jQlite is also known as jQuery lite is a subset of jQuery and contains all its features. It is packaged within Angular, by default. It helps Angular to manipulate the DOM in a way that is compatible cross-browser. jQLite basically implements only the most commonly needed functionality which results in having a small footprint.

13. On which types of the component can we create a custom directive?

Angular provides support to create custom directives for the following:

  • Element directives − Directive activates when a matching element is encountered.
  • Attribute − Directive activates when a matching attribute is encountered.
  • CSS − Directive activates when a matching CSS style is encountered.
  • Comment − Directive activates when a matching comment is encountered

14. What is Transpiling in Angular?

Transpiling in Angular refers to the process of conversion of the source code from one programming language to another. In Angular, generally, this conversion is done from TypeScript to JavaScript. It is an implicit process and happens internally.

15. How to perform animation in Angular?

In order to perform animation in an Angular application, you need to include a special Angular library known as Animate Library and then refer to the ngAnimate module into your application or add the ngAnimate as a dependency inside your application module.

16. What is transclusion in Angular?

The transclusion in Angular allows you to shift the original children of a directive into a specific location within a new template. The ng directive indicates the insertion point for a transcluded DOM of the nearest parent directive that is using transclusion. Attribute directives like ng-transclude or ng-transclude-slot are mainly used for transclusion.

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