Web / Angular Interview questions

Difference between Promises and Observable.

Promise.	Observable.
A Promise handles only one event when an async operation completes or fails.	An Observable is like a Stream and accepts 0 or more (multiple) events where the callback is called for each event.
Promise doesn't support cancelation.	Observables are cancelable.
Promises execute immediately on creation.	Observables are declarative and computation does not start until subscription.
Promises provide only one value.	Observables provide many values.
Promises push errors to the child promises for error handling.	Observables subscribe() is responsible for handling errors that provides centralized and predictable error handling.

More Related questions...

What is AngularJS? What are the key features of AngularJS. What are the advantages of using AngularJS? What are the key components of AngularJS Framework? What are the limitations of using AngularJS? Explain about AngularJS Expression. Can we pass parameters to an AngularJS controller? What is bower? What is a component in Angular? What are .ts extension files? How do you communicate between different modules of your application using angularjs? How does interpolation, for example "{{ someModel }}" works? What is $rootScope and how does it relate to $scope? Advantages of components in AngularJS. What is ngBind directive in AngularJS? What is ngIf directive in Angular? Difference between ng-show/ng-hide directives and ngIf in angularjs. Explain directives in Angular. What is the role of selector property of components in AngularJS? Explain Angular architecture. Type of module in Angular 2. Explain root module in angular2. What is an Angular module? What does the npm start do? How do I create a multiline template in the Angular component? What is RXJS and how does it relate to Angular? How to check if a variable is defined using ngIf in Angular? How to check for multiple conditions using Angular ng-if? Features of Angular2. Explain ng-container in Angular. Types of directives in Angular. Difference between Directive and component in Angular. Difference between ngOnInit and ngAfterViewInit of Angular2. Difference between Constructor and ngOnInit in Angular. What is a zone in Angular? Can we use ngIf and ngFor on the same element in Angular? What is router-link directive? Difference between router-link and [router-link] with brackets. Explain Hot Module Replacement (HMR). What is webpack? Difference between ng model and ng bind directives. What is forRoot and forChild method in angular? How do you create and register/provide service using ng CLI? Difference between declarations, providers, and import in NgModule. Explain pipes in Angular. What is angular routing? How to check the Angular version installed? Explain the structure of Angular application projects. What is angular CLI? Elements of the Component decorator in Angular. Explain Angular services. How do I create a service as a singleton in Angular? What is service worker and its advantages in Angular? How does *ngIf directive works? Difference between ng-class and ng-style directives. Difference between Component and template/templateURL. Default view encapsulation model in Angular. What is Ivy in Angular? Types of directives in Angular. What are structural directives in Angular? Difference between Structural and attribute directives. What is <ng-template> in Angular? Explain <ng-container> element in Angular. Name a few builtin pipes in Angular that you are aware of. What are the different types of Pipes in Angular? What is JsonPipe? What are the methods in Angular FormBuilder? What is ngForm directive? What are the child classes of AbstractControl? Difference between Promises and Observable. What is NGModule? Can a Angular component be declared in multiple modules? Design a game using Angular in which the user should click on the highlighted area to score before it vanishes. Also, it should display score with different levels like easy/medium/difficult. What is tree shaking in Angular? What defines an Angular view? Difference between a view, a host view, and an embedded view. Difference between createEmbeddedView and createComponent in Angular. Various forms of data binding markup in Angular. Is ngModel an attribute directive? Mention a few roles of Services in Angular. How do I make a parent component listen for child events? What is the difference between CSS and SCSS? What is router outlet in Angular? What are angular guards? Mention a few drawbacks (disadvantages) of using Angular. What is Angular Universal or Angular SSR? Explain index signature in typescript. Can we consume SOAP web service with Angular Application? Key features of IndexedDB. What is Web worker in Angular? How do you handle right-click event on a DIV in Angular? How do you handle double-click in Angular? What is a nested route in Angular? Types of LocationStrategy in Angular routes. Difference between RouterModule.forRoot() and forChild(). What is APP_INITIALIZER in Angular? Advantages of SCSS over CSS? Why do we need to use Angular? Difference between AngularJS vs Angular. Types of Angular directives. Explain the importance of NPM and node_modules folder? What is the package.json file in Angular? What is typescript and why do we need it? What is schematics in Angular? Explain the importance of Components and Modules? What is Decorator in Angular? What is metadata/annotation in Angular. What is a template in Angular? Different types of data binding in Angular. What is SPA in Angular? How to detect when an @Input() value changes in Angular? What are PWAs? What is the Jasmine test framework? What is Setup and Teardown in Jasmine? What is Karma in Angular testing? What is the use of the Protractor framework in Angular? Explain the purpose of SubSink in Angular. What is NgRx? Can we do two way binding without ngModel? If so, how? What are HostListener and HostBinding? Why using ElementRef is not recommended? What is Angular Unit Testing? How does code coverage work in angular 7? What is single component Angular modules (SCAM)?

Show more question and Answers...

ReactJS Interview questions

Comments & Discussions

Angular Interview questions 124 ReactJS Interview questions 64 Typescript interview questions 22 NodeJS Interview questions 14 Nativescript interview questions 5 React native Interview questions 51 ES6 Interview questions 7 ES8 Interview questions 3 RxJs Interview questions 17 HTML Interview questions 9 JSP interview questions 6 TanStack Interview Questions 38

Recently added questions

How do you search for UDM events in Google SecOps? What is Gemini in Google SecOps used for? What is Chronicle SOAR? What is Google Threat Intelligence? How do you ingest logs into Google SecOps? What is data retention in Google SecOps? What is the Unified Data Model (UDM)? What is Chronicle SIEM? What is a playbook in Google SecOps SOAR? What are curated detections? What are the required sections of a YARA-L rule? What is a parser in Google SecOps? What is a forwarder in Google SecOps? What are reference lists used for? What is Google SecOps? What is the purpose of Google SecOps? What is YARA-L? What are the core components of Google SecOps? Define a case in Google SecOps SOAR? List the ways to access Google SecOps search?

	Interviews Questions Java Spring Hibernate DevOps Testing API BigData Web Erlang AI Database Integration Cloud Python Scala Tools Golang SAP	About Javapedia.net Javapedia.net is for Java and J2EE developers, technologist and college students who prepare of interview. Also this site includes many practical examples. This site is developed using J2EE technologies by Steve Antony, a senior Developer/lead at one of the logistics based company. Follow Javapedia updates
	contact: javatutorials2016[at]gmail[dot]com
Kindly consider donating for maintaining this website. Thanks.
	Copyright © 2026, javapedia.net, all rights reserved. Privacy Policy · Terms of Service.