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Angular 7 interview questions

Last update: 30 Mar 2020, 15 QuestionsAsk Question
A Quick Overview of Angular7
Angular 7 interview questions

Angular 7 is a JavaScript web application development framework used to create Single Page Applications (SPAs). This is one of the foremost front-end development frameworks which has been regularly updated by the Angular team of Google. If you are scrolling on the web for Angular 7 interview questions and answers pdf, then this guide will gonna help you.

Now, if you are a fresher, you should start with some basic Angular7 Questions. If you already have hands-on coding knowledge and understand the basic terminologies, its time for you to jump on to the advanced Angular7 Questions which involve more complexities.

Note: If you are a beginner, it is highly advised not to skip this section.

Angular 7
What is Angular 7? Angular 7 is a JavaScript web application development framework used to create Single Page Applications (SPAs). This is one of the foremost front-end development frameworks which has been regularly updated by the Angular team of Google.
Latest Version Angular 9.0. released in November 2019.
Created By Google
Written in TypeScript

Basic Level Angular 7 Interview Questions

In Angular, during each navigation route, the Router sends navigation events through the Router Events property.

Here is the list of events range from when the navigation starts and ends too many points in between.

  • NavigationStart
  • RouteConfigLoadEnd
  • GuardsCheckStart
  • ActivationStart
  • GuardsCheckEnd
  • ResolveStart
  • ActivationEnd
  • NavigationEnd

Example

                                                    

export class AppComponent {
   constructor(private router: Router) {
   }
   ngOnInit() {
      this.router.events
      .pipe(filter(event => event instanceof NavigationEnd))
      .subscribe(() => {
         ...
       });
   }
}

Here are the reasons to use an AOT compiler in Angular:

  • Faster rendering: Using the AOT compiler, browsers can download a pre-compiled version of the application. This ensures that the browser can render the application immediately using executable code without having to wait for the whole compilation.
  • Less asynchronous requests: Using inline external HTML templates and CSS style sheets within the application, the compiler eliminates separate ajax requests for those specific resource files.
  • Reduced Angular framework download size: There's no need to download the Angular compiler if the app is already compiled. This is very advantageous and efficient as the compiler is almost half the size of Angular, so, not having to add that increases the application payload dramatically.
  • Optimized Error Handling: Detecting existing template errors and reporting template binding errors during the building step before users can see.
  • Enhanced Security: Compilation of HTML templates and other components into JS files before client-side rendering. This reduces the scope for risky JS evaluation or injection attacks. The AOT compiler the HTML templates and other components into JS files before they are served to the client. With no templates to read and no risky client-side JavaScript or HTML evaluation, there are fewer opportunities for injection attacks.

The command, ng generate service [service name] generates a service in Angular.

An API stands for Application Programming Interface. It is basically a set of rules and tools for building software applications. In AngularJS, the Global API is a combination of global functions written in Javascript which are used for tasks like comparing/iterating objects or converting data.

The main difference between Angular 7 and Angular 6 is -
Differentiable parameters Angular 7 Angular 6
Features The main features that Angular 7 contains are- CLI prompts, Angular Material, Component Dev Kit (CDK), Virtual scrolling, and Application Performance Improvements, Angular Material, etc. The main features that Angular 6 contained are- Angular CLI Workspaces, ng update, ng add, Angular Elements, Animations Performance Improvements, Bazel compiler, service worker safety, etc.
Prime focus Angular 7 primarily focused on upgrading the existing features rather than publishing advanced level features. Angular 6 primarily focused on adding new features and bring new extensible upgrades.
Angular Material and Components Dev Kit (CDK) The Angular 7 framework has minor changes in the improvement of material design. The Angular 6 framework has major changes in the improvement of material design.
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Angular 7 has new and advanced level features such as

  • Modernized v7.0.2 CLI prompts
  • Reflect- metadata poly-fill part for application performance
  • Angular material and CDK ( Component Dev Kit)
  • Virtual scrolling package
  • Drag and Drop <@angular/cdk/drag-drop>
  • Angular compatibility compiler (ngcc)
  • angular Do-bootstrap
  • improved error handling
  • dependency updates etc

In addition to all these features, Angular 7 also provides Documentation updates which include Angular console, @angular/Fire, NativeScript, StackBlitz, and Bazel, platform- browser, etc.

In Angular 7, templates are written with the help of HTML that contains Angular JS specification elements and attributes. The main role of Angular 7 is to combine the templates which ultimately control the dynamic view that is visible to the users in the browsers.

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Structural directive

The main function of the structural directive is to shape and re-shape the HTML layout, and DOM’s structure. The modification and customization of HTML layout are done by adding, removing and manipulating the selected HTML elements.

Attribute directives

The attribute directive has its own layout view and styles because it has a single component on a host element but it supports multiple directives.

Angular 7 has two core dependencies namely RxJS and TypeScript
  • RxJS 6.3 – Angular 7 framework uses RxJS version 6.3.
  • TypeScript- Angular 7 framework uses TypeScript version 3.1

Advanced Level Angular 7 Interview Questions

The utility functions provided by Angular are:

  • map() : Used to map values of different data types
  • filter() : Used for filtering streams
  • concat() : Used to concatenate multiple strings
  • merge(): Used to recursively descend into object properties in the source copy, while forming a deep copy of the same.

The Router.navigate is used to specify a root URL through relative navigation. Here’s a function using the above to navigate through different articles in Angular:

Example

                                                    

gotoDetails(articleId: any) {
   this.router.navigate(['/blog/', blogId]);
}

Steps to update Angular 6 to Angular 7 are
  • Remove deprecated features and components of RxJS 6 with the help of auto-update rules from rxjs-tslint.
  • Install the tool by using command npm install –g rxjs-tslin
  • From the root of your project run rxjs-5-to 6-migrate –p scr/tsconfig.app.json
  • remove rxjs-compat library from rxjs-5-to 6-migrate –p scr/tsconfig.app.json
  • Run command ng update @angular/[email protected]/core

Your Angular version gets updated to v7

UrlSegment is a modified feature of Angular 7 which is used to add a new interface. In other words, UrlSegment Interface feature represents URL segment, constructor, properties and methods which are present in UrlSegment class. Moreover, UrlSegement is one of the parts of URL, as it contains metric and path parameters which are associated and interlinked with the segment.

In order to set headers for every request in Angular 7, HTMLHttpRequest is used. There is a number of benefits such as testability features, types request, request and response interception, observable APIs and streamlined error handling that is associated with, XMLHttpRequest.

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Additionally, Angular 7 contains a number of advanced features namely CLI prompts, Component Dev Kit (CDK), drag and drop, virtual Scrolling and improvement in application performance. Given listed questions are the widely asked Angular 7 interview questions and answers. The development of Angular 7 framework is based on several components forming a tree structure hierarchy with parents and child components.

Features of Angular 7

  • Enhanced application performance
  • Angular material and the component dev kit
  • Virtual scrolling & Drag and drop
  • Improved accessibility for selects
  • CLI prompt

Angular 7 is a widely used JavaScript web application development framework. The Angular 7 framework improves the upgrading process. In this blog post commonly asked Angular 7 interview questions are discussed with appropriate answers. Angular 7 has attractive features and standardized specifications such as core Framework, major partner launches, and synchronized significant versions of CLI, advanced chains and Angular material.

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