37 Angular 7 interview questions and answers that get you a new Job in 2019-2020

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Do you have experience in Angular 7 development and look for a new job? As you might know, even if your resume is very convincing, it is not a guarantee that you have got this job. A key decision is usually made during or after the interview. Therefore, it is important to prepare for this responsible stage and look through Angular 7 interview questions and answers in advance. You may agree that sometimes it is difficult to make up a clear response to the answer, especially if you are nervous. However, if you get the idea of what questions might be there, it will empower you to present yourself from the best side.

Look: this article will list you 37 most popular Angular 7 interview questions and answers to them for you to show off your expertise level

Angular 7 interview questions and answers

Angular 7 is one of the most widely used tools for front-end development of web applications. However, it is a complex technology that can be mastered not by every person and requires much experience from the developer to be able to perform certain tasks with its help. Therefore, many companies desire to check the professionalism of Angular developers during the interview before hiring them. These Angular 7 interview questions will help every developer improve his hiring strategy and achieve the desirable goal.

What are the pros of Angular 7?

This framework has become incredibly popular thanks to the number of advantages it features:

  • It completes a variety of tasks for the developer saving his time and minimizing the number of errors;
  • Fast performance;
  • It allows separating out the code of the app developed which is great for collaboration;
  • A consistent and easy to maintain code base;
  • A big number of features and well-organized front-end structure;
  • Mobile-first approach for developing cross-platform apps;
  • Powerful Command Line Interface etc.

angular 7

What is the difference between Angular 7 and its previous versions?

Unlike Angularjs, the seventh version of the framework is a component-based one. It uses TypeScript for building applications and is based on Service/Controller. It also features an improved usability and performance as well as a bigger number of features giving developers a bigger flexibility.

Which dependencies does Angular 7 framework have?

The latest version of the framework supports three dependencies:

  • Typescript 3.1;
  • RxJS 6.3;
  • Node 10.

What basic parts does every Angular app have?

A basic app developed with the help of this framework should include the following parts:

  • Modules;
  • Component;
  • Data Binding;
  • Template;
  • Directives;
  • Dependency Injection;
  • Services;
  • Routing.

The basic building blocks in this framework are NgModules responsible for providing compilation context for components.

What difficulties are faced by developers using Angular 7?

Since this framework has been created for developing Single Page Applications, there are often troubles with the performance of dynamic apps. Moreover, the tool offers multiple ways to complete the same task and it may lead to some confusion among developers. Other negative features of this tool are its complexity and difficulty of learning, so it always requires time to find necessary details on the web.

What are new features of Angular 7?

When it comes to the new features of this popular framework, in addition to a new interface and standard set, developers have received the following novelties:

  • Virtual scrolling;
  • Use of drag-and-drop function due to @angular/cdk/drag-drop module;
  • Automatic changes to the library;
  • Easier error handling;
  • Support for Node 10;
  • Angular downloadable console;
  • Native Script feature for developing both mobile and web app immediately;
  • Selects have become more accessible;
  • Automated render when a user is moving items;
  • Helper Method for reordering and transferring items in the list;
  • The Bundle Budget feature to warn developers about too large app size etc.

new features of Angular 7

How do developers handle events in Angular 7?

In fact, there are three basic ways to handle events in this popular framework:

1. Binding to answer events of users

Angular event binding can be used by means of answering to DOM event triggered by user input. One of the examples look as follows: <button (click)=”onClickMe()”>Click me!</button>

2. Event object can provide with a user input

Much information carried by DOM is considered valuable for components. This example suggests the input box event showing how to get a user’s input after each stroke:

src/app/keyup.components.ts (template v.1)
content_copy
template: `
<input (keyup)=”onKey($event)”>
<p>{{values}} </p>

3. Filter key events

The event handler hears every keystroke. Enter keys reflect people signs presented by typing. If you want to minimize noise, follow every $event.keyCode and the action will happen only when you press the enter key.

How do structural directives differ from attribute ones?

Developers use Structural directives with the goal to change the DOM layout and providing extra DOM elements.

Characteristics of elements are guaranteed by attribute directives.

What is the basic language of Angular 7 and what are its features?

TypeScript language is the main language of Angular 7 framework. Being similar to JavaScript, its main benefit is elimination of popular mistakes which occur when a developer types the code. The main advantages of TypeScript are better navigation, autocompletion, and refactoring services.

What is a module in Angular 7?

Logical boundaries in the app are called modules. They include a collection of services, filters, directives, controllers, and configuration information. The basic module used for coding is NgModule. It is necessary to load NgModule which is used to declare every app created.

What is known as Transpiling in Angular 7?

The transfer of one programming language source code into another one is called Transpiling. When a developer uses Angular, it usually involves converting TypeScript into JavaScript. This process can be performed in an automatic and internal manner.

What is AOT compilation?

AOT is translated as Ahead-of-time compilation – the process when the code written for an app is compiled at build time before a developer runs the app in the browser. This type of compilation is needed for a better app performance.

What is lazy loading and how is it used in Angular development?

The main role of module lazy loading is to divide the code into parts. When a newly created app is downloaded in the web browser, the app code is loaded by pieces, not fully. This type of loading keeps initial bundle sizes smaller and it helps to minimize the loading time.

What is the difference between shared and core modules?

A shared module is a generic module for every module, component, directive, pipe, etc. that are to be imported into many other modules and do not require a copy for an app. A core module serves as a storage for services that are needed for the app operation.

How can a developer secure Angular 7 app?

One of the main tasks of a developer is not only to create an app but also make it secure and it can be achieved using several practices:

  • Ensure that every request comes from the web application developed, not external sites;
  • Have all input data sanitized;
  • Prefer to use Angular template to DOM API;
  • Follow content security policy;
  • Make all data validated with server-side code;
  • Make use of a template compiler working offline;
  • Nerve include other URL addresses in the app;
  • Change JSON responses for non-executable ones;
  • Update libraries and frameworks regularly.

How to test Angular 7 apps?

There are two popular testing methods used with this framework: end-to-end and unit testing. The last one aims at testing isolated segments of code, while end-to-end tests are performed to check the whole set of components and ensue in their smooth and proper work. The most popular tools used for testing apps are Jasmine and Karma, though now the framework has its own testing framework called TestBed.
start angular 7

What to use with Angular Bindings: constructor or ngOnInit?

TypeScript language features a default method constructor which is responsible for initialization purposes, but when it comes to Angular, it has its own method called ngOnInit which is great for defining Angular bindings. Despite that the constructor is activated first, experts advise moving every binding to ngOnInit method, which can be implemented with the help of OnInit.

export class App implements OnInit{
constructor(){
//called first time before the ngOnInit()
}
ngOnInit(){
//called after the constructor and called after the first ngOnChanges()
}
}

What is a component in Angular 7?

Logical pieces of code for the framework are called components. The last one consists of three constituent parts:

  1. Template, which is used for rendering the view for apps;
  2. Class that contains properties and methods and has a code to support the view;
  3. Metadata – additional data defined for the Angular class with a decorator.

What is bootstrapping?

Bootstrapping process means initializing or starting an Angular application and it can be of two types: automatic and manual one. If the process is performed automatically, the framework is looking for the ng-app directive and performs three more steps: loads the module associated with directive, crest an app injector and compiles the DOM starting from the ng-app root element. Manual bootstrapping is activated by using angular.bootstrap() function. The last one takes the modules as parameters and is a result of the call of angular.element(document).ready() function, which is fired when the DOM is prepared for manipulation.

What is a pipe?

Pipe is a feature that takes input data and transforms it into a necessary output. Pipes can be connected in a variety of ways to get the most useful combinations. There are ready-made pipes included in the framework (e.g. DatePipe, UpperCasePipe, LowerCasePipe, CurrencyPipe, and PercentPipe) and developers can write their own pipes too.

How are a component and a module connected?

Components are logical pieces of code in Angular 7 framework. It consists of templates and its main role is to render the app view because it contains its HTML.

Component is a constituent part of the module. The last one can consist of 1 or 2 components. The main role of modules is to declare the destiny of components by managing them and bringing modularity to the application.

How can a developer control AOT compilation?

It is possible to control the application compilation in two simple ways:

  1. If you provide a template compiler option in tsconfig.json file;
  2. If you configure the framework metadata with decorators.

What utility functions does RxJS provide?

The list of functions performed by RxUS looks as follows:

  • It converts existing code for async operations into observables;
  • It iterates through the values in a stream;
  • It maps values to different types;
  • It filters streams;
  • It composes multiple streams.

What is multicasting and how does it look in Angular 7?

Multicasting is a situation where every notification sent by a single observable is received by multiple observers. Only hot observables are multicast, while cold observable can be made multicast following the model: a source observable; a subject subscribed to the source; and multiple observers subscribed to the subject.

How can you add HTTP headers to every request in Angular?

The process of addicting HTTP headers to requests in Angular 7 consists of the following stages:

  • Creating HTTP interceptor
  • Adding token to the request
  • Registering the Interceptor

What is the role of JIT compiler?

Just-in-time compiler is responsible for compiling the app dynamically while it is loading. There are 3 providers that tell this compiler how to translate a template text for a particular language:

  • TRANSLATIONS is a string containing the content of the translation file.
  • TRANSLATIONS_FORMAT is the format of the file.
  • LOCALE_ID is the locale of the target language.

What is Angular Ivy and what DOM does it use?

Angular Ivy is a framework render that uses incremental DOM. This DOM is used internally at Google and according to it, every component is compiled into a certain series of instructions, which created DOM trees and update them each time when there are any changes in data. The main reason to use incremental DOM is in the necessity to create applications what work well on mobile devices too. It is worth noting that components are not interpreted by this type of DOM, they reference instructions.

How do pure pipes differ from impure ones in Angular 7?

The main difference between these types of pipes lies in the changes that make them work. Pure pipe works only when the component is loaded detecting a change in the value or parameters passed to it. Impure pipes are called each time when there is a change in the detection cycle or component. It is possible to make the pipe pure/impure in the following way:
@Pipe({
name: ‘sort’,
pure: false //true makes it pure and false makes it impure
})
export class myPipe implements PipeTransform {

transform(value: any, args?: any): any {
//your logic here and return the result
}

}

What is Angular Router?

Router is used for enabling different views that change during the process of app task performance. It interprets browser URLs as instructions for navigating the view preferred by the client. It is an optional service that must be imported from the Angular package. A router receives roots and determines them only if it was configured.

How to add authentication information to requests?

Angular 7 has a great feature of HttpInterceptor that allows intercepting and modifying HTTP requests. This feature also allows attaching authentication information to requests using several different forms. The most popular way is to attach JSON Web Token or any other token as an Authorization header with the Bearer scheme.

What is understood under string interpolation in Angular 7?

Known as moustache syntax, the term ‘string interpolation’ is a syntax type that uses template expressions with the goal of displaying component data. The main feature of such template expressions is being enclosed writhing double curly braces i.e. {{ }}.
However, if there is a necessity to execute JavaScript expressions, it is necessary to embrace them with curly braces and this output is embedded into the HTML code.

What is scope hierarchy in Angular 7?

Most of the $scope objects are organised into hierarchy by Angular and this type of organization is often used by views. Every hierarchy has a root scope with several more scopes known as child ones.

Every view in the scope hierarchy features its own $scope. It means that every amiable set by a certain view controller will be invisible to other controllers. There is an example of scope hierarchy:

  • Root $scope
  • $scope for Controller 1
  • $scope for Controller 2
  • ..
  • .
  • $scope for Controller n

What is the difference between Angular 7 and AngularJS?

Being one of the most popular Angularjs 7 interview questions, this example has become in the list of questions for Angular 7 interview too. The reason for that is a great difference between these frameworks including the following features:

  • Architecture – the MVC design model dominates AngularJS framework while both components and directives are the basis of Angular 7.
  • Dependency Injection (DI) – A hierarchical Dependency Injection with unidirectional tree-based change detection is supported by Angular 7 but not AngularJS.
  • Expression Syntax – AngularJS syntax requires a specific ng directive to display both the image or property and an event. In Angular 7, blinding an event and accomplishing property binding require () and [] braces.
  • Mobile Support – only Angular 7 has a mobile support.
  • Recommended Language – JavaScript for AngularJS, TypeScript for Angular 7.
  • Routing – AngularJS uses $routeprovider.when() whereas Angular uses @RouteConfig{(…)}.
  • Speed – Angular 7 is faster due to upgraded features, but without them, a 2-way data binding used in AngularJS makes it faster.
  • Structure – Angular 7 features a simplified structure which is easy to develop and maintain in the apps. The structure is AngularJS is not that manageable.
  • Support – Angular 7 can boast an active support with regular updates and a huge development community, though there is no official support in AngularJS.

What is the difference between an annotation and a decorator?

Annotations are used in this framework to create an annotation array. They are referred to a metadata set of the class that uses the Reflect Metadata library.

Design patterns required for separating decoration or modification of classes not changing the original source code are called decorators.

What is known as Angular Material?

Being a component library for the framework, Angular Material has components that are used to construct appealing, consistent, and functional web pages and web applications following modern web design principles including browser portability, device independence, and graceful degradation.

How to explain the term ‘digest cycle’ in Angular 7?

Digest cycle is a process of following the watchlist with the goal to spot changes in The watch variable value. The comparison of the previous and current scope model versions is performed during every digest cycle.
It is activate implicitly, but a developer can trigger it manually too making use of $apply() function.

What is ViewEncapsulation in Angular 7?

ViewEncapsulation is a function created with the goal to determine if the styles defined in the component are going to impact the entire app. There are three types of this function:

  • Emulated – Styles used in other HTML spread to the component
  • Native – Styles used in other HTML doesn’t spread to the component
  • None – Styles defined in a component are visible to all components of the application

Conclusion

Angular 7 is a complex framework that is unique in its structure and work, therefore recruiters will be interested how well a job-seeker knows the terms and functionality of this development system. This article has focused on the most popular interview questions on Angular 7 but this list is not full since there are hundreds of practical tasks which can be used during an interview too. However, if you manage to impress the potential employer with great knowledge of the theory, there will be no sense to ask for anything else.

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