Angular 2 Interview Questions

A set of accurately designed Angular 2 interview questions will help you crack the interview. To get acquainted with the questions and their answers which you might encounter during the interview is extremely important. Let us learn about the Angular 2 interview questions and answers in detail. You can mug up on the given set of questions and answers because even if you do not face the same set, you would be able to answer the questions in relation to them. An overview of the most important concepts will always keep you one step ahead in your interview.

An Overview of Angular 2
What is Angular 2? A set of accurately designed Angular 2 interview questions will help you crack the interview. To get acquainted with the questions and their answers which you might encounter during the interview is extremely important.
Latest Version Angular 8.0. released on May 28, 2019
Created By Google
Written in TypeScript
Official Website https://angular.io/

Most Frequently Asked Angular 2 Interview Questions and answers

In order to put the logical boundaries distinct for any application, models are used in angular JS. Apart from coding it also requires a single build-up for everything in separate modules to differentiate its functionality.

It is made up of the following parts-
  1. Bootstrap array- it is used to mention about the components which need to be loaded
  2. Export array- in order to export the components it is used along with accessing it for the application
  3. Import array- it is used to import the components, pipes or directives.

Every application has it well-defined components where component refers to a logical boundary of the functioning for any application. Also, you would require the layered services that can be utilized to share the same functioning all across the components.

A component in angular 2 consists of-
  • Class- This is similar to Java or C class considering the properties and other methods.
  • Template- This is used for defining the HTML view which gets displayed.
  • Metadata- This is used for class decoration for extending the functionality of it.

Angular 2 offers some of the main advantages as-

  • It was created to facilitate in the mobile application industry
  • It has absolute browser compatibility supporting the Internet Explorer 9,10,11, Chrome, Safari, Firefox, Android along with Microsoft edge
  • It is also cross-platform flexible through which developers can formulate various applications running on the desktop systems
  • It delivers maximum performance as it has a highly optimized subset of JavaScript
  • It helps in code generation through which template can easily be turned into the code
  • It is of course cost-effective
Some of the drawbacks of angular 2 are-
  • There are plenty of ways to do a task hence it gets confusing for a newbie
  • Typescript has significance in angular 2 because it has a steep learning curve
  • If you are proficient in angular then learning angular 2 will be a whole new thing
  • It offers slow user interface and Thursday developer has to face major lag
  • It also follows the inconsistent documentation because it has a fragmented community
  • The documentation of angular 2 lacks well-written codes and consistent approaches

The mechanism which allows navigation easier in between multiple views with the help of components and then allows the user to configure it making them more flexible is routing. It also allowed the features by providing lazy loading to facilitate the load times and then increases performance.

It is used to achieve-
  • For the creation of modular applications
  • For the state management in any of the application segment

In Angular 2 routing helps to provide a role which is based upon authorization for any of the application and provide access to a large number of users to utilize certain parts of the same application.

It is done in the following steps-
  • Creating a module to store the necessary routing path and then defining them along with the routes
  • Important the module for the application by app.module.ts and then adding the routing module name as per the imports of @NgModule
  • Adding the tags of routing selector to the components HTML
  • Adding the router links for easy navigation and to index.htm

Ahead of time or AOT refers to the compiler in the sequence of processes rather than compiling them at the run time in the browser. The components are compiled at the built-in time and then converted into native JavaScript followed by HTML.

Advantages:
  • It provides detection for built-in time error and then detects them before running.
  • It also helps in fast rendering
Disadvantages:
  • It requires a cleanup step prior to compiling
  • It only works selectively like HTML and CSS

This is most frequently asked Angular 2 interview questions and answers.

The tsconfig.json file is used to provide multiple options about the typescript which is used in the angular 2 projects. {
"compilerOptions":{
"target": "es5",
"module": "commonjstest",
"moduleResolution": "node",
"sourceMap": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"lib": [ "es2017", "demo" ],
"noImplicitAny": true,
"suppressImplicitAnyIndexErrors": true
}
}

The app.module.ts file can be represented by the following code.

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
@NgModule({
imports: [ BrowserModule ],
declarations: [ AppComponent ],
bootstrap: [ AppComponent ] })
export class AppModule { }

This is most frequently asked Angular 2 interview questions and answers.

Codelyzer refers to an open-source tool that is used to run or detect if the predefined coding guidelines are followed or not. It only performs the static code analysis in angular 2 and typescript project because all platforms follow a set of easy and conventional coding to maintain it in a better way. Codelyzer also runs on the top of tslint where its coding convention is completely defined in the tslint.json file. The developer can also run it through an angular click.

Lazy loading enables the user to load only the required module through which the user is interacting and keeps the rest of the modules to be loaded during the runtime on-demand. It also speeds up the initial load time of any application by splitting code into various small bundles and then loads them on demand. Every Angular 2 application has at least one main module for example App module. The code must be capable to split into various child modules entirely based upon their business case.

This can be done by-
  • Importing the top-level component
  • Describe it using @ symbol
  • Create the instances of @directive, @injectable and many more
  • Add the metadata say like providers, styles, templates or selector
  • Export the component
  • Bootstrap the component
Refer to one example-

import { Component } from '@angular/ core';
import { bootstrap } from '@angular/ platform-browser-dynamic';

@Component({
selector: 'my-test',
styles: [`

h1 {
color:#000000;
padding:5px;
}
`]

template:
` <h1>Hi There! This is {{componentName}}.</h1>
` })
export class TestComponent {
componentName: 'TestComponent'
}
bootstrap(TestComponent);

Angular 2 is not just limited with a general upgrade but it refers to a unique form of development. This whole new framework is rewritten from the basics and has successfully eliminated some of the unwanted factors like controllers, DDO, $scope, angular.module and many more. It also utilizes the components for the majority of the tasks. It also takes benefits from the typescripts syntax and ES6 where is development in the same segment is more powerful. A number of other instances are also developed and redesigned in angular 2 like template engine and so on.

The custom HTML element which is used for extending the power of it is known as a directive. In angular 2 they are known as the BrowserModule module.

  • nglf- this element is used to add the elements in the HTML code. Its syntax is- *ngIf = 'expression'
  • If the expression is evaluated to be true then the corresponding value gets added and if not then the element will not be added.
  • ngFor- element is used for the elements based on For Loop condition. It's syntax is- *ngFor = 'let variable of variable list'

Using the angular routing command it gets easier to navigate through the view page or any other file during any tasks. One can also configure the URL to redirect any other URL and this feature can also be handled to address the problem of "404 not found". By using the location services one can go back and forward along with the page history. Its syntax is- e can use {path: '/OUR_PATH', redirectTo: ['redirectPathName']}

NOTE: This is one of the most common Angular 2 interview questions.

Activatedroute Routerstate
It is made up of data which is about the root association along with a component which is loaded in an outlet It represents the developer’s actual state
It contains entire data from where the route got altered It was on the application components sequence and arrangement
ActivatedRoute Snapchat is required to traverse the multiple activated routes The router creates its snapshot while navigation once all the redirects have already been applied

The applications in angular 2 have an error handling option which also includes the react JS library to use the catch function. In turn, the catch function includes a link that sends information about the error handler function. under this function one can send the error as a question to console file other instances will send it back in the main program to ensure the continuation of the operation of the main program. This is one of the most common Angular 2 interview questions. Once it is fixed whenever the error arises it will be redirected in the browser's console.