đź“šAngular Interview Questions Part 1

On this article we’re going to see a properly curated record of angular interview questions 2021 and solutions for skilled in addition to freshers.



Why have been client-side frameworks like Angular launched?

The arrival of contemporary JavaScript frameworks has made it a lot simpler to construct extremely dynamic, interactive purposes.

JS frameworks are JavaScript code libraries which have pre-written code to make use of for routine programming options and duties. It’s actually a framework to construct web sites or net purposes round.

A framework is a library that provides opinions about how software program will get constructed. These opinions permit for predictability and homogeneity in an utility; predictability permits software program to scale to an infinite dimension and nonetheless be maintainable; predictability and maintainability are important for the well being and longevity of software program.

Angular is an open-source net utility framework led by the Angular Crew at Google and by a group of people and firms. It’s a full rewrite from the identical group that constructed AngularJS. Angular was formally launched on the 14th of September 2016.

Angular is a component-based framework which makes use of declarative HTML templates. At construct time, transparently to builders, the framework’s compiler interprets the templates to optimized JavaScript directions.



What are lifecycle hooks in Angular?

Angular Lifecycle hooks are totally different states of an angular purposes element or directive by means of out the time of its instantiation to time when its destroyed. These lifecycle hooks are invoked at totally different phases and situations of angular utility.

The lifecycle continues with change detection, as Angular checks to see when data-bound properties change, and updates each the view and the element occasion as wanted.

We are able to use any of those lifecycle hooks to faucet into explicit occasion or state of the applying to carry out activity’s as required.

Under are the lifecycle hooks:

ngOnChanges(): Referred to as at any time when a number of data-bound enter properties change simply earlier than earlier than ngOnInit().

ngOnInit(): Referred to as as soon as, after the primary ngOnChanges() and angular has insantiated the element

ngDoCheck(): Referred to as on each change detection run, and as soon as after ngOnChanges() and ngOnInit() respectively. The aim of this lifecycle hook is to behave upon adjustments that Angular cannot or will not detect by itself.

ngAfterContentInit(): Referred to as as soon as after the primary ngDoCheck(). The aim of this lifecycle hook is to reply after angular has completed loading any exterior knowledge into its element.

ngAfterContentChecked(): Referred to as after ngAfterContentInit() and each subsequent ngDoCheck(). The aim of this lifecycle hook is to examine the content material projected into the directive or element.

ngAfterViewInit(): Referred to as as soon as after the primary ngAfterContentChecked(), This lifecycle hook is invoked when angular initializes the element’s views and youngster views
ngAfterViewChecked(): Referred to as after the ngAfterViewInit() and each subsequent ngAfterContentChecked(). This lifecycle hook is invoked after angular checks the element’s views and youngster views, or the view that comprises the directive.

ngOnDestroy(): Referred to as instantly earlier than Angular destroys the directive or element. We are able to use this lifecycle hook for Cleanup simply earlier than Angular destroys the directive or element. Unsubscribe Observables and detach occasion handlers to keep away from reminiscence leaks.



Clarify Parts, Modules and Providers in Angular

Parts in Angular are the primary constructing block for Angular purposes. Every element consists of 4 information by default .html, .much less, .ts and .spec.ts. A element is principally a wrapper for our presentation layer and the logical layer.

An HTML template that declares what renders on the web page. A Typescript class that defines habits. A CSS selector that defines how the element is utilized in a template.

Module in Angular are principally a container for all of the code blocks within the utility. We declare and import all companies, pipes, directives and elements within the default fundamental module created by angular at time of venture creation which is the AppModule. We are able to create multiple modules for our utility and lazy or keen load as per our requirement. An angular module is outlined with the @NgModule() decorator.

Providers in Angular are method of speaking between the elements of an Angular utility and sharing knowledge between them. We are able to make our code modular and re-usable via companies as it may be used throughout the applying. Providers in angular are declared with use of the @Injectable() decorator.



What are directives in Angular?

Directives are courses that add further habits to components in your Angular purposes. Directives are principally customized HTML attributes which Angular offers us In-built to make use of and a few of which we are able to create by ourselves.

Under are the several types of Directives

Structural Directives:

These are the kind of directives which helps us to create DOM Objects. We are able to add DOM objects and take away DOM objects inside our utility dynamically by utilizing these two directives.

*ngFor: Loop over the Array of objects creating HTML components on which the directive is used.
*ngIf: Add or take away the HTML aspect from DOM relying upon the situation specified.

Attribute Directives:

These are the kind of directives which helps us to alter the appear and feel and habits of our HTML components, attributes, properties, and elements.

NgClass: provides and removes a set of CSS courses.
NgStyle: provides and removes a set of HTML kinds.
NgModel: provides two-way knowledge binding to an HTML kind aspect.

Element Directives:

These are the varieties of directives with a template. This kind of directive is the commonest directive kind. This Specifies that an Angular element can also be a kind of Directive.



What’s Angular Router?

Angular Router is a Routing service for our angular utility supplied by Angular. Which we are able to import and use in our Software. We want specify the Array of Routes to this service and import it in our AppModule. This service is required for Navigating by means of totally different elements/view of our angular utility.



What’s Angular Materials?

Angular Materials is a cloth UI element library constructed by the Angular group to combine seamlessly with Angular purposes. Angular Materials offers in-built prepared to make use of elements that helps in creating minimal, elegant and useful, HTML components and pages. It consists of properly examined elements to make sure efficiency and reliability with easy APIs and constant cross platform habits.

Angular Materials offers instruments that assist builders construct their very own customized elements with widespread interplay patterns. It helps in creating sooner, stunning, and responsive web sites. It’s impressed by the Google Materials Design.



What’s string interpolation in Angular?

String Interpolation in Angular is methodology to bind knowledge from the logical layer to the presentation layer. We are able to bind our ts variables in our html instantly by utilizing this mechanism known as as string Interpolation which is denoted by double curly braces.

Under is the instance

//ts file
title: String = 'Angular Software';
Enter fullscreen mode

Exit fullscreen mode

//html file
{{ title }} 
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Exit fullscreen mode



How does one share knowledge between elements in Angular?

Following are the commonest methods by which we are able to share knowledge between angular elements:

@Enter: The @Enter methodology is used once we wish to cross knowledge from mother or father to youngster.

@Output: The @Ouput methodology is used once we wish to cross knowledge from youngster to mother or father by utilizing it EventEmmitter function.
Providers: Providers are the commonest method of sharing knowledge throughout a number of elements as its declared within the root of the element.



Listing out variations between AngularJS and Angular

Angular JS is the primary ever model of Angular and relies on Javascript. The place because the Angular is totally primarily based on Typescript which is a superset of Javascript and has backward compatibility.

Angular JS, primarily based on JavaScript, makes use of phrases of scope and controllers whereas Angular makes use of a hierarchy of elements. Angular is component-based whereas AngularJS makes use of directives.

Angular relies on fashionable net purposes platform and we are able to develop cross platform purposes with single angular code.

Checkout different Articles on Angular Interview Questions sequence from under Hyperlinks

Half 1 of this sequence :- Angular Interview Questions Part 1

Half 2 of this sequence :- Angular Interview Questions Part 2

Half 3 of this sequence :- Angular Interview Questions Part 3

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