Angular 8 Interview Questions and Answers

Angular 8 it has following new features such as

• Differential loading- It is a technique that automatically makes your angular applications more performant. When you build applications for production, two bundles are created- One bundle for Modern browsers that support ES6+ and another bundle for older browsers that only support ESS.
• Dynamic imports for lazy routes- In Angular version 8 there is nothing new in the concept of lazy routes itself but the syntax has totally changed. In the older version of Angular CustomString Syntax is used, but angular 8 uses standard dynamic import syntax so the syntax which is customized to Angular is migrated to industrial standard.
• Ivy rendering Engine- It translates the templates and components into regular HTML and javascript that the browser can interpret and understand.
• Bazel- It is a building tool through which angular developer can build backends and frontends.

Steps for the Installation of Angular 8 environmental setup

Step 1

Before installing Angular IDE using Angular CLI tool, make sure that Node.js has already installed in your system.

• 1. If Node.js is not installed in your system install it using the following steps.
  • The basic requirement of Angular 8 is Node.js version 110.9.0 or later.
  • Download it using https://nodejs.org/en/
  • Install it on your system
  • Open node.js command prompt
  • Check the version run command, node-v in the console window

Step 2

In order to install Angular CLI, use the following commands 2) npm install –g @angular/cli or npm install –g @angular/cli@latest

Step 3

To check the node and angular CLI version, run command ng –version on the console terminal

Angular 8 introduced a number of new and unique options to runGuardsAndResolvers. In general, runGuardsAndResolvers is an option which is used for the Angular router configuration in order to control the resolvers and guards. The first option available in runGuardsAndResolvers is pathParamsChange. Through, this option router will re-run the guards and resolvers. Whenever you want to control over the resolvers and guards, use runGuardsAndResolvers option in Angular 8.

Steps to upgrade Angular 7 to 8

• Install TypeScript 3.4
• Use Node LTS 10.16 or its advanced version
• Run command on terminal panel/CLI -> ng update @angular/cli@angular/core

Alternative- use URL link- https://update.angular.io/

In Angular 8, Bazel is a new build system and it is available for a short period of time. It is the new feature of Angular 8, which provides a platform to make your backends and frontends with a similar tool. It has the possibility to have remote builds as well as cache on the build farm.

The main features of Bazel are-

• It is an internal build tool, through which application can be customized.
• It also tests the action and performance of multiple machines.
• It constructs a graph through which you can identify the useful information.
• It also supports customization.

The main features of Bazel are-

• It is an internal build tool, through which application can be customized.
• It also tests the action and performance of multiple machines.
• It constructs a graph through which you can identify the useful information.
• It also supports customization.

Angular 8 has advanced level features which ensure systematic workflow and performance improvements. It has apparent features such as differential loading, CLI workflow improvements, Dynamic imports for lazy routes, Ivy rendering engine, Bazel, etc.

The working of typesofchecks in Angular 8 is similar with the enabled and disabled flag, which means if you want to test whether the selected value is an object or not, then the following syntax is used " Typeof value = = = 'object' ". In angular 8 the folwing types of checks are used such as “Typeof value.ngOnDestroy = = = 'function' “.

The angular router in Angular 8 enables rollback the whole object to the next as users perform application work. To present a specific component view a given URL, Angular Router is the foremost service that presents. In order to import an Angular router, it is mandatory to install a library package, @angular/router.

In Angular 8, the framework does not interpret components in an incremental DOM. It uses component references instructions, and if it does not refer to a particular instruction, it shall be left unused. Now, VIrtual DOM requires an external interpreter. Hence, not knowing which components to display, everything is shifted to the browser, making the DOM shakeable.

Wildcard routing is used in Angular 8 for defining the route of pages. Specific changes/updates can be made when defining the route using Wildcard.

Codelyzer is an open-source tool in Angular 8 whose main function is to check for errors in codes not following pre-defined guidelines. It runs on the tslint.json file and checks only the static code in Angular 8.

Angular 8 uses observables which are implemented using RxJS libraries to push code. The main job of RxJS is to work with asynchronous events.

To detect router change in Angular 8, the $on() method is used. This is an event handler used to handle $routeChangeSuccess when triggered by a route/view change or update.

NgUpgrade in Angular 8 is a library which is used to integrate both Angular and AngularJS components in an application and also help in bridging the dependency injection systems in both Angular & AngularJS.

A Service Worker is used in Angular 8 to build the basic steps of converting an application into a Progressive Web App (PWA). Service workers function as network proxies and intercepting all outgoing HTTP requests made by the application and how to respond.

Here are the top new features of Angular 9

• An undecorated class migration schematic added to the core.
• Numeric Values are accepted in the formControlName.
• Selector-less directives have now been allowed as base classes in View Engine in the compiler.
• Conversion of ngtsc diagnostics to ts.Diagnostics is possible

Here are the limitations of a Web Worker:

• A web worker cannot directly manipulate the DOM
• It has limited access to methods and properties of the window object.
• It cannot be run directly from the file system. A web worker needs a server to run.

The ng lint command is used to run static code analysis within an Angular application.

Ng-hide command is used to hide HTML elements if an expression is true.

Here's an example:

<div ng-app="DemoApp" ng-controller="DemoController">
   <input type="button" value="Hide Angular" ng-click="ShowHide()"/>
   <div ng-hide="IsVisible">Angular 8</div>
</div>
<script type="text/javascript">
   var app = angular.module('DemoApp',[]);
   app.controller('DemoController',function($scope){
   $scope.IsVisible = false;
   $scope.ShowHide = function(){
     $scope.IsVisible = $scope.IsVisible = true;
   }
});
</script>

Now in the above, when the Hide Angular button is not clicked(the expression is set to false)

Angular uses TypeScript because:

• It has a wide range of tools
• It’s a superset of Angular
• It makes abstractions explicit
• It makes the code easier to read and understand.
• It takes most of the usefulness within a language and brings it into a JS environment without forcing you out.