Angular Interview Questions

What is Angular?

Angular is a TypeScript-based open-source web application framework, developed and maintained by Google.
It offers an easy and powerful way of building front end web-based applications.
Angular integrates a range of features like declarative templates, dependency injection, end-to-end tooling, etc. that facilitates web application development.

Please explain the various features of Angular?

Could you explain services in Angular?

Singleton objects in Angular that get instantiated only once during the lifetime of an application are called services.
An Angular service contains methods that maintain the data throughout the life of an application.
The primary intent of an Angular service is to organize as well as share business logic, models, or data and functions with various components of an Angular application.
The functions offered by an Angular service can be invoked from any Angular component, such as a controller or directive.

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 }}

What are templates in Angular?

Templates in Angular are written with HTML that contains Angular-specific elements and attributes.
These templates are combined with information coming from the model and controller which are further rendered to provide the dynamic view to the user.

In Angular what is string interpolation?

String interpolation in Angular is a special syntax that uses template expressions within double curly {{ }} braces for displaying the component data.
It is also known as moustache syntax.
The JavaScript expressions are included within the curly braces to be executed by Angular and the relative output is then embedded into the HTML code.
These expressions are usually updated and registered like watches, as a part of the digest cycle.

What do you understand by controllers in Angular?

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:
- Component Directives
- Structural Directives
- Attribute Directives

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.

What is the purpose of a filter in Angular?

Filters in Angular are used for formatting the value of an expression in order to display it to the user.
These filters can be added to the templates, directives, controllers or services.
Not just this, you can create your own custom filters.
Using them, you can easily organize data in such a way that the data is displayed only if it fulfills certain criteria.
Filters are added to the expressions by using the pipe character |, followed by a filter.

What is a provider in Angular?

A provider is a configurable service in Angular.
It is an instruction to the Dependency Injection system that provides information about the way to obtain a value for a dependency.
It is an object that has a $get() method which is called to create a new instance of a service.
A Provider can also contain additional methods and uses $provide in order to register new providers.

What is the difference between $scope and scope in Angular?

$scope in Angular is used for implementing the concept of dependency injection (D.I) on the other hand scope is used for directive linking.
$scope is the service provided by $scopeProviderwhich can be injected into controllers, directives or other services whereas Scope can be anything such as a function parameter name, etc.

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.

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.

What is the difference between a link and compile in Angular?

Compile function is used for template DOM Manipulation and to collect all the directives.
Link function is used for registering DOM listeners as well as instance DOM manipulation and is executed once the template has been cloned.

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