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1001 (actually more than ~1500) Full Stack Interview Questions And Answers sourced from all around the Internet to help you to prepare to an interview, conduct one, mock your lead dev or completely ignore. Answers provided for Junior and Middle-Level questions. All answers available on FullStack.Cafe.

• ASP.NET
• AWS
• Agile
• Angular
• AngularJS
• Azure
• Behavioral
• Bootstrap
• CSS
• Code Problems
• Data Structures
• Design Patterns
• DevOps
• Git
• Golang
• GraphQL
• HTML 5
• Java
• JavaScript
• Laravel
• MongoDB
• Node.js
• Performance Testing
• Questions to Ask
• REST API
• React
• Ruby
• Sass
• Scrum
• Software Architecture
• TypeScript
• UX Design
• Vue.js
• Web Security
• Webpack

Answer: The .NET Core platform is a new .NET stack that is optimized for open source development and agile delivery on NuGet.

.NET Core has two major components. It includes a small runtime that is built from the same codebase as the .NET Framework CLR. The .NET Core runtime includes the same GC and JIT (RyuJIT), but doesn’t include features like Application Domains or Code Access Security. The runtime is delivered via NuGet, as part of the ASP.NET Core package.

.NET Core also includes the base class libraries. These libraries are largely the same code as the .NET Framework class libraries, but have been factored (removal of dependencies) to enable to ship a smaller set of libraries. These libraries are shipped as System.* NuGet packages on NuGet.org.

Source: stackoverflow.com

Answer: ASP.NET Core is a brand new cross-platform web framework built with .NET Core framework. It is not an update to existing ASP.NET framework. It is a complete rewrite of the ASP.NET framework. It works with both .NET Core and .NET Framework.

Main characterestics of ASP.NET Core:

• DI Container which is quite simple and built-in. You can extend it with other popular DI containers
• Built-in and extensible structured logging. You can redirect output to as many sources as you want (file, Azure, AWS, console)
• Extensible strongly typed configuration, which can also be used to reload at run-time
• Kestrel – new, cross-platform and super fast web server which can stand alone without IIS, Nginx or Apache
• New, fully async pipeline. It is easily configured via middleware
• ASP.NET All meta package which improves development speed, and enables you to reference all Microsoft packages for ASP.NET Core and it will deploy only those that are being used by your code
• There is no web.config. We now use appsettings.json file in combination with other sources of configuration (command line args, environment variables, etc.)
• There is no _Global._asax – We have Startup.cs which is used to set up Middleware and services for DI Container.

Source: talkingdotnet.com

Answer: Yes. This might surprise many, but ASP.NET Core works with .NET framework and this is officially supported by Microsoft.

ASP.NET Core works with:

• .NET Core framework
• .NET framework

Source: talkingdotnet.com

Answer: Another crucial part of ASP.NET Core Framework is Configuration. Also, it is part of Dependency Injection. Use it anywhere in your code with an option to reload on changes of configuration values from sources (appsettings.json, environment variables, command line arguments, etc.). It is also easy to override, extend and customize the Configuration. No more extensive configurations in web.config, the preferred way now is appsettings.json in combination with a mix of Environment variables and cmd-line args.

Source: talkingdotnet.com

Answer: Logging is built-in and you get access to structured logs from the ASP.NET Core host itself to your application. With tools like Serilog, you can extend your logging easily and save your logs to file, Azure, Amazon or any other output provider. You can configure verbosity and log levels via configuration (appsettings.json by default), and you can configure log levels by different categories.

Source: talkingdotnet.com

Answer: Everything starts from Program.cs

public static void Main(string[] args)
{
    BuildWebHost(args).Run();
}
 
public static IWebHost BuildWebHost(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>()
        .Build();

CreateDefaultBuilder extension method will create a default configuration which will look first into appsettings.json files then will look for Environment variables and at the end, it will use command line arguments.

This part will also set up default logger sources (debug and console) and load the settings for logging from appsettings.json.

After the CreateDefaultBuilder finishes, then Startup class is executed. First, the constructor code is executed. After that, services are added to DI container via AddServices method that lives in Startup class. After that, an order of middleware that will handle every incoming request is set up.

Source: codingblast.com

Answer: To be simple:

• Mono is third party implementation of .Net Framework for Linux/Android/iOs
• .Net Core is Microsoft's own implementation for same.

Source: stackoverflow.com

Answer: Razor Pages is a new feature of ASP.NET Core that makes coding page-focused scenarios easier and more productive.

With Razor Pages, you have this one Razor file (.cshtml), and the code for a single page lives inside of that file, and that file also represents the URL structure of the app. Therefore, you got everything inside of one file, and it just works.

However, you can separate your code to the code behind file with .cshtml.cs extension. You would usually have your view model and handlers (like action methods in MVC) in that file and handle the logic there. Of course, you could also have your view model moved to separate place.

Since Razor Pages is part of the MVC stack, you can use anything that comes with MVC inside of our Razor Pages.

Source: codingblast.com

Answer:

• Flexible deployment: Can be included in your app or installed side-by-side user- or machine-wide.

• Cross-platform: Runs on Windows, macOS and Linux; can be ported to other OSes. The supported Operating Systems (OS), CPUs and application scenarios will grow over time, provided by Microsoft, other companies, and individuals.

• Command-line tools: All product scenarios can be exercised at the command-line.

• Compatible: .NET Core is compatible with .NET Framework, Xamarin and Mono, via the .NET Standard Library.

• Open source: The .NET Core platform is open source, using MIT and Apache 2 licenses. Documentation is licensed under CC-BY. .NET Core is a .NET Foundation project.

• Supported by Microsoft: .NET Core is supported by Microsoft, per .NET Core Support

Source: stackoverflow.com

Answer:

• The SDK is all of the stuff that is needed/makes developing a .NET Core application easier, such as the CLI and a compiler.

• The runtime is the "virtual machine" that hosts/runs the application and abstracts all the interaction with the base operating system.

Source: stackoverflow.com

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Answer: AWS stands for Amazon Web Services and is a platform that provides database storage, secure cloud services, offering to compute power, content delivery, and many other services to develop business levels.

Source: onlineinterviewquestions.com

Answer:

• Simple Storage Service (S3): S3 is most widely used AWS storage web service.
• Simple E-mail Service (SES): SES is a hosted transactional email service and allows one to fluently send deliverable emails using a RESTFUL API call or through a regular SMTP.
• Identity and Access Management (IAM): IAM provides improved identity and security management for AWS account.
• Elastic Compute Cloud (EC2): EC2 is an AWS ecosystem central piece. It is responsible for providing on-demand and flexible computing resources with a “pay as you go” pricing model.
• Elastic Block Store (EBS): EBS offers continuous storage solution that can be seen in instances as a regular hard drive.
• CloudWatch: CloudWatch allows the controller to outlook and gather key metrics and also set a series of alarms to be notified if there is any trouble.

Source: whizlabs.com

Answer: An Amazon S3 bucket is a public cloud storage resource available in Amazon Web Services' (AWS) Simple Storage Service (S3), an object storage offering. Amazon S3 buckets, which are similar to file folders, store objects, which consist of data and its descriptive metadata.

By default, you can create up to 100 buckets in each of your AWS accounts. If you need more buckets, you can increase your bucket limit by submitting a service limit increase.

Source: whizlabs.com

Answer: Amazon CloudFront is a content delivery network (CDN) offered by Amazon Web Services. Content delivery networks provide a globally-distributed network of proxy servers which cache content, such as web videos or other bulky media, more locally to consumers, thus improving access speed for downloading the content.

Source: en.wikipedia.org

Answer: AMI stands for the term Amazon Machine Image. It’s an AWS template which provides the information (an application server, and operating system, and applications) required to perform the launch of an instance. This AMI is the copy of the AMI that is running in the cloud as a virtual server. You can launch instances from as many different AMIs as you need. AMI consists of the followings:

• A root volume template for an existing instance
• Launch permissions to determine which AWS accounts will get the AMI in order to launch the instances
• Mapping for block device to calculate the total volume that will be attached to the instance at the time of launch

Source: whizlabs.com

Answer: Use scp:

scp -i ec2key.pem username@ec2ip:/path/to/file .

Source: stackoverflow.com

Answer: You can make an AMI of an existing instance, and then launch other instances using that AMI.

Source: stackoverflow.com

Answer: AWS Data Pipeline is a web service that you can use to automate the movement and transformation of data. With AWS Data Pipeline, you can define data-driven workflows, so that tasks can be dependent on the successful completion of previous tasks.

Source: docs.aws.amazon.com

Answer: Amazon EC2 services have following features:

• Virtual Computing Environments
• Proffers Persistent storage volumes
• Firewall validating you to specify the protocol
• Pre-configured templates
• Static IP address for dynamic Cloud Computing

Source: whizlabs.com

Answer: Many different types of instances can be launched from one AMI. The type of an instance generally regulates the hardware components of the host computer that is used for the instance. Each type of instance has distinct computing and memory efficacy.

Once an instance is launched, it casts as host and the user interaction with it is same as with any other computer but we have a completely controlled access to our instances. AWS developer interview questions may contain one or more AMI based questions, so prepare yourself for the AMI topic very well.

Source: whizlabs.com

Answer: Yes, buckets exist in a specific region and you need to specify that region when you create a bucket. Amazon S3 creates bucket in a region you specify. You can choose any AWS region that is geographically close to you to optimize latency, minimize costs, or address regulatory requirements.

Source: stackoverflow.com

Answer: AWS Direct Connect bypasses the public Internet and establishes a secure, dedicated connection from your infrastructure into AWS. With established connectivity via AWS Direct Connect, you can access your Amazon VPC and all AWS services.

Source: coresite.com

Answer: Amazon Elastic Block Store (Amazon EBS) provides persistent block storage volumes for use with Amazon EC2 instances in the AWS Cloud. Each Amazon EBS volume is automatically replicated within its Availability Zone to protect you from component failure, offering high availability and durability.

Source: aws.amazon.com

Answer: AWS Lambda is a serverless compute service that runs your code in response to events and automatically manages the underlying compute resources for you. You can use AWS Lambda to extend other AWS services with custom logic, or create your own back-end services that operate at AWS scale, performance, and security.

Source: aws.amazon.com

Answer: Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. With DynamoDB, you can create database tables that can store and retrieve any amount of data, and serve any level of request traffic.

Source: docs.aws.amazon.com

Answer: Amazon Elastic MapReduce (EMR) is an Amazon Web Services (AWS) tool for big data processing and analysis. Amazon EMR offers the expandable low-configuration service as an easier alternative to running in-house cluster computing.

Amazon EMR is based on Apache Hadoop, a Java-based programming framework that supports the processing of large data sets in a distributed computing environment. MapReduce is a software framework that allows developers to write programs that process massive amounts of unstructured data in parallel across a distributed cluster of processors or stand-alone computers.

Source: searchaws.techtarget.com

Answer: By default data on S3 is not encrypted, but all you could enable server-side encryption in your object metadata when you upload your data to Amazon S3. As soon as your data reaches S3, it is encrypted and stored.

Source: aws.amazon.com

Answer: No. After you create a volume, you can attach it to any EC2 instance in the same Availability Zone. An EBS volume can be attached to only one EC2 instance at a time, but multiple volumes can be attached to a single instance.

Source: docs.aws.amazon.com

Answer: Amazon API Gateway is an AWS service that enables developers to create, publish, maintain, monitor, and secure APIs at any scale. You can create APIs that access AWS or other web services, as well as data stored in the AWS Cloud.

Source: aws.amazon.com

Answer: Using AWS Direct Connect, you can establish private connectivity between AWS and your datacenter, office, or colocation environment, which in many cases can reduce your network costs, increase bandwidth throughput, and provide a more consistent network experience than Internet-based connections.

Source: aws.amazon.com

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Answer: To improve the performance, the existing code is modified; this is re-factoring. During re-factoring the code functionality remains same.

Source: career.guru99.com

Answer: User stories are features customers might want to see in their software. They are written on index cards to encourage face-to-face communication. Typically no more than a couple days work, they form the basis of our Agile plans.

Answer: An Agile iteration is a short one to two week period where a team takes most important user stories, builds them completely and deliver as running-tested-software to the customer. Analysis, design, coding, testing happen during an iteration.

Answer: Test driven development (TDD) is also known as test-driven design. In this method, developer first writes an automated test case which describes new function or improvement and then creates small codes to pass that test, and later re-factors the new code to meet the acceptable standards.

Source: career.guru99.com

Answer: Velocity is a metric that is calculated by addition of all efforts estimates related with user stories completed in an iteration. It figures out how much work Agile can complete in a sprint and how much time will it need to finish a project.

Source: career.guru99.com

Answer: A product roadmap is referred for the holistic view of product features that create the product vision.

Source: career.guru99.com

Answer: Agile is a time boxed, iterative approach (framework) to software delivery that builds software incrementally from the start of the project, instead of trying to deliver it all at once near the end.

It works by breaking projects down into little bits of user functionality called user stories, prioritizing them, and then continuously delivering them in short two week cycles called iterations.

Agile refers to any process that aligns with the concepts of the Agile Manifesto.

Source: agilemanifesto.org

Answer:

• Analysis, design, coding, and testing are continuous activities
• Development is iterative
• Planning is adaptive
• Roles blur
• Scope can vary
• Requirements can change
• Working software is the primary measure of success

Answer: The burn-down chart shows the remaining work to complete before the timebox (iteration) ends.

Source: career.guru99.com

Answer: If a timebox plan needs to be reprioritized it should include whole team, product owner, and developers.

Source: career.guru99.com

Answer: It is used to discuss the difficulty of the story without assigning actual hours. The most common scale used is a Fibonacci sequence (1, 2, 3, 5, 8,1 3,….100) although some teams use linear scale (1, 2, 3, 4….), Powers of 2 (1, 2, 4, 8……) and cloth size (XS, S ,M, L, XL)

Source: career.guru99.com

Answer: To track the project progress burnup and burn down, charts are used

• Burnup Chart: It shows the progress of stories done over time
• Burndown Chart: It shows how much work was left to do overtime

Source: career.guru99.com

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Answer: Angular’s route guards are interfaces which can tell the router whether or not it should allow navigation to a requested route. They make this decision by looking for a true or false return value from a class which implements the given guard interface.

Source: medium.com

Answer: An Angular module is set of Angular basic building blocks like component, directives, services etc. An app can have more than one module.

A module can be created using @NgModule decorator.

@NgModule({
  imports:      [ BrowserModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

Source: stackoverflow.com

Answer: A pipe takes in data as input and transforms it to a desired output. You can chain pipes together in potentially useful combinations. You can write your own custom pipes. Angular comes with a stock of pipes such as DatePipe, UpperCasePipe, LowerCasePipe, CurrencyPipe, and PercentPipe.

Consider:

<p>The hero's birthday is {{ birthday | date }}</p>

In this page, you'll use pipes to transform a component's birthday property into a human-friendly date.

Source: angular.io

Answer: Components control views (html). They also communicate with other components and services to bring functionality to your app.

Modules consist of one or more components. They do not control any html. Your modules declare which components can be used by components belonging to other modules, which classes will be injected by the dependency injector and which component gets bootstrapped. Modules allow you to manage your components to bring modularity to your app.

Source: stackoverflow.com

Answer: Angular and AngularJS is basically a different framework with the same name.

Angular is more ready for the current state of web standards and the future state of the web (ES6\7, immutiablity, components, shadow DOM, service workers, mobile compatibilty, modules, typescript and so on and so on... )

Angular killed many main features in AngularJS like - controllers, $scope, directives (replaced with @component annotations), the module definition, and much more, even simple things like ng-repeat has not left the same as it was.

Also:

1. They added an angular cli.
2. Your angular code is written in ES6 Typescript and it compiles at runtime to Javascript in the browser.
3. You bind to your HTML similarly like how you would if in an Angular 1 directive. So variable like $scope and $rootScope have been deprecated.

Source: stackoverflow.com

Answer: Angular services are singleton objects which get instantiated only once during the lifetime of an application. They contain methods that maintain data throughout the life of an application, i.e. data does not get refreshed and is available all the time. The main objective of a service is to organize and share business logic, models, or data and functions with different components of an Angular application.

The separation of concerns is the main reason why Angular services came into existence. An Angular service is a stateless object and provides some very useful functions.

Source: dzone.com

Answer: Just bind to the hidden property

Source: stackoverflow.com

Answer: The absolute minimal configuration for a @Component in Angular is a template. Both template properties are set to optional because you have to define either template or templateUrl.

When you don't define them, you will get an exception like this:

No template specified for component 'ComponentName'

A selector property is not required, as you can also use your components in a route.

Source: stackoverflow.com

Answer: The correct syntax is the following:

<div [innerHTML]="theHtmlString"></div>

Working in 5.2.6

Source: medium.com

Answer: Components are the most basic building block of an UI in an Angular application. An Angular application is a tree of Angular components. Angular components are a subset of directives. Unlike directives, components always have a template and only one component can be instantiated per an element in a template.

A component must belong to an NgModule in order for it to be usable by another component or application. To specify that a component is a member of an NgModule, you should list it in the declarations field of that NgModule.

@Component({selector: 'greet', template: 'Hello {{name}}!'})
class Greet {
  name: string = 'World';
}

Source: angular.io

Answer: You can get a handle to the DOM element via ElementRef by injecting it into your component's constructor:

constructor(myElement: ElementRef) { ... }

Source: medium.com

Answer: Just bind to the hidden property:

[hidden]="!myVar"

Source: medium.com

Answer: *ngIf effectively removes its content from the DOM while [hidden] modifies the display property and only instructs the browser to not show the content but the DOM still contains it.

Source: medium.com

Answer:

• Directives add behaviour to an existing DOM element or an existing component instance.
• A component, rather than adding/modifying behaviour, actually creates its own view (hierarchy of DOM elements) with attached behaviour.

Write a component when you want to create a reusable set of DOM elements of UI with custom behaviour. Write a directive when you want to write reusable behaviour to supplement existing DOM elements.

Source: medium.com

Answer: Just to name a few:

• Improvements in AOT,
• allowing the "else" clause in ngIf,
• support for TypeScript 2.1
• breaking out the animations package

Source: github.com/WebPredict

Answer: The Angular router ships with a feature called guards. These provide us with ways to control the flow of our application. We can stop a user from visitng certain routes, stop a user from leaving routes, and more. The overall process for protecting Angular routes:

• Create a guard service: ng g guard auth
• Create canActivate() or canActivateChild() methods
• Use the guard when defining routes

// import the newly created AuthGuard
const routes: Routes = [
  {
    path: 'account',
    canActivate: [AuthGuard]
  }
];

Some other available guards:

• CanActivate: Check if a user has access
• CanActivateChild: Check if a user has access to any of the child routes
• CanDeactivate: Can a user leave a page? For example, they haven't finished editing a post
• Resolve: Grab data before the route is instantiated
• CanLoad: Check to see if we can load the routes assets

Source: scotch.io

Details:

@HostBinding('[class.valid]') isValid;

Answer: @HostBinding lets you set properties on the element or component that hosts the directive.

The code applies the css class valid to whatever is using this directive conditionally based on the value of isValid.

Source: alligator.io

Answer: The Angular CLI downloads and install everything you need to test an Angular application with the Jasmine test framework.

The project you create with the CLI is immediately ready to test. Just run this one CLI command:

ng test

Source: angular.io

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Answer: There are following reasons to choose AngularJS as a web development framework:

1. It is based on MVC pattern which helps you to organize your web apps or web application properly.
2. It extends HTML by attaching directives to your HTML markup with new attributes or tags and expressions in order to define very powerful templates.
3. It also allows you to create your own directives, making reusable components that fill your needs and abstract your DOM manipulation logic.
4. It supports two-way data binding i.e. connects your HTML (views) to your JavaScript objects (models) seamlessly. In this way any change in model will update the view and vice versa without any DOM manipulation or event handling.
5. It encapsulates the behavior of your application in controllers which are instantiated with the help of dependency injection.
6. It supports services that can be injected into your controllers to use some utility code to fullfil your need. For example, it provides $http service to communicate with REST service.
7. It supports dependency injection which helps you to test your angular app code very easily.
8. Also, AngularJS is mature community to help you. It has widely support over the internet.

Source: github.com/krosti

Answer: ng-show/ng-hide will always insert the DOM element, but will display/hide it based on the condition. ng-if will not insert the DOM element until the condition is not fulfilled.

ng-if is better when we needed the DOM to be loaded conditionally, as it will help load page bit faster compared to ng-show/ng-hide.

We only need to keep in mind what the difference between these directives is, so deciding which one to use totally depends on the task requirements.

Source: codementor.io

Answer: AngularJS has no dependency on jQuery library. But it can be used with jQuery library.

Source: _ github.com/krosti_

Answer: This can be done by using the ng-hide directive in conjunction with a controller to hide an HTML element on button click.

<div ng-controller="MyCtrl">
    <button ng-click="hide()">Hide element</button>
    <p ng-hide="isHide">Hello World!</p>
</div>

function MyCtrl($scope) {
	$scope.isHide = false;
	$scope.hide = function () {
		$scope.isHide = true;
	};
}

Source: codementor.io

Answer: Is a great pattern that restricts the use of a class more than once. We can find singleton pattern in angular in dependency injection and in the services.

In a sense, if the you do 2 times new Object() without this pattern, the you will be alocating 2 pieces of memory for the same object. With singleton pattern, if the object exists, it'll be reused.

Source: codementor.io

Answer: The features of AngularJS are listed below:

1. Modules
2. Directives
3. Templates
4. Scope
5. Expressions
6. Data Binding
7. MVC (Model, View & Controller)
8. Validations
9. Filters
10. Services
11. Routing
12. Dependency Injection
13. Testing

Source: github.com/krosti

Answer: A module might have dependencies on other modules. The dependent modules are loaded by angular before the requiring module is loaded.

In other words the configuration blocks of the dependent modules execute before the configuration blocks of the requiring module. The same is true for the run blocks. Each module can only be loaded once, even if multiple other modules require it.

Source: github.com/krosti

Answer: To prevent accidental name collisions with your code, Angular prefixes names of public objects with $ and names of private objects with $$. So, do not use the $ or $$ prefix in your code.

Source: github.com/krosti

Answer: Filters are used to format data before displaying it to the user. They can be used in view templates, controllers, services and directives. There are some built-in filters provided by AngularJS like as Currency, Date, Number, OrderBy, Lowercase, Uppercase etc. You can also create your own filters.

Filter Syntax:

{{ expression | filter}}

Source: github.com/krosti

Answer: AngularJS directives are a combination of AngularJS template markups (HTML attributes or elements, or CSS classes) and supporting JavaScript code. The JavaScript directive code defines the template data and behaviors of the HTML elements.

AngularJS directives are used to extend the HTML vocabulary i.e. they decorate html elements with new behaviors and help to manipulate html elements attributes in interesting way.

There are some built-in directives provided by AngularJS like as ng-app, ng-controller, ng-repeat, ng-model etc.

Source: github.com/krosti

Answer: Directives are markers on a DOM element (such as an attribute, element name, comment or CSS class) that tell AngularJS’s HTML compiler ($compile) to attach a specified behavior to that DOM element (e.g. via event listeners), or even to transform the DOM element and its children.

Angular comes with a set of these directives built-in, like ngBind, ngModel, and ngClass. Much like you create controllers and services, you can create your own directives for Angular to use. When Angular bootstraps your application, the HTML compiler traverses the DOM matching directives against the DOM elements.

Source: codementor.io

Answer: Scope is an object that refers to the application model. It is an execution context for expressions. Scopes are arranged in hierarchical structure which mimic the DOM structure of the application. Scopes can watch expressions and propagate events. Scopes are objects that refer to the model. They act as glue between controller and view.

Source: codementor.io

Answer: The ngIf Directive, when applied to an element, will remove that element from the DOM if it’s condition is false.

Source: codementor.io

Answer:

• One way binding implies that the scope variable in the html will be set to the first value its model is bound to (i.e. assigned to)
• Two way binding implies that the scope variable will change it’s value everytime its model is assigned to a different value

Source: codementor.io

Answer: Angular initializes automatically upon DOMContentLoaded event or when the angular.js script is downloaded to the browser and the document.readyState is set to complete. At this point AngularJS looks for the ng-app directive which is the root of angular app compilation and tells about AngularJS part within DOM. When the ng-app directive is found then Angular will:

1. Load the module associated with the directive.
2. Create the application injector.
3. Compile the DOM starting from the ng-app root element. This process is called auto-bootstrapping.

<html>
<body ng-app="myApp">
<div ng-controller="Ctrl"> Hello {{msg}}!
</div>
    <script src="lib/angular.js"></script>
    <script>
var app = angular.module('myApp', []); app.controller('Ctrl', function ($scope) {
              $scope.msg = 'World';
          });
    </script>
</body>
</html>

Source: github.com/krosti

Answer: By using “::” in front of it.

Source: codementor.io

Answer: Scope is a JavaScript object that refers to the application model. It acts as a context for evaluating angular expressions. Basically, it acts as glue between controller and view.

Scopes are hierarchical in nature and follow the DOM structure of your AngularJS app. AngularJS has two scope objects: $rootScope and $scope.

Source: github.com/krosti

Answer: We can use the ng-disabled directive and bind its condition to the checkbox’s state.

<body ng-app>
    <label>
        <input type="checkbox" ng-model="checked" />Disable Button
    </label>
    <button ng-disabled="checked">Select me</button>
</body>

Source: codementor.io

Answer: The $scope object used by views in AngularJS are organized into a hierarchy. There is a root scope, and the $rootScope can has one or more child scopes. Each controller has its own $scope (which is a child of the $rootScope), so whatever variables you create on $scope within controller, these variables are accessible by the view based on this controller.

For example, suppose you have two controllers: ParentController and ChildController as given below:

<html>
  <head>
    <script src="lib/angular.js"></script>
    <script>
      var app = angular.module('ScopeChain', []); app.controller("parentController", function ($scope) {
      	$scope.managerName = 'Shailendra Chauhan';
      	$scope.$parent.companyName = 'Dot Net Tricks'; //attached to $rootScope
      });
      app.controller("childController", function ($scope, $controller) {
                 $scope.teamLeadName = 'Deepak Chauhan';
             });
         
    </script>
  </head>
  <body ng-app="ScopeChain">
    <div ng-controller="parentController ">
      <table style="border:2px solid #e37112">
        <caption>Parent Controller</caption>
        <tr>
          <td>Manager Name</td>
          <td>{{managerName}}</td>
        </tr>
        <tr>
          <td>Company Name</td>
          <td>{{companyName}}</td>
        </tr>
        <tr>
          <td>
            <table ng-controller="childController" style="border:2px solid #428bca">
              <caption>Child Controller</caption>
              <tr>
                <td>Team Lead Name</td>
                <td>{{ teamLeadName }}</td>
              </tr>
              <tr>
                <td>Reporting To</td>
                <td>{{managerName}}</td>
              </tr>
              <tr>
                <td>Company Name</td>
                <td>{{companyName}}</td>
              </tr>
            </table>
          </td>
        </tr>
      </table>
    </div>
  </body>
</html>

Source: github.com/krosti

Answer: Create an AngularJS service that will hold the data and inject it inside of the controllers.

Using a service is the cleanest, fastest and easiest way to test. However, there are couple of other ways to implement data sharing between controllers, like:

– Using events
– Using $parent, nextSibling, controllerAs, etc. to directly access the controllers
– Using the $rootScope to add the data on (not a good practice)

The methods above are all correct, but are not the most efficient and easy to test.

Source: codementor.io

Answer:

• Inject the module that contains the filter.
• Provide any mocks that the filter relies on.
• Get an instance of the filter using $filter('yourFilterName').
• Assert your expectations.

Source: codementor.io

Answer:

1. Inject the module that contains the filter.
2. Provide any mocks that the filter relies on.
3. Get an instance of the filter using $filter('yourFilterName').
4. Assert your expectations.

Source: codementor.io

Answer: There are following advantages of AngularJS:

1. Data Binding - AngularJS provides a powerful data binding mechanism to bind data to HTML elements by using scope.
2. Customize & Extensible - AngularJS is customized and extensible as per you requirement. You can create your own custom components like directives, services etc.
3. Code Reusability - AngularJS allows you to write code which can be reused. For example custom directive which you can reuse.
4. Support – AngularJS is mature community to help you. It has widely support over the internet. Also, AngularJS is supported by Google which gives it an advantage.
5. Compatibility - AngularJS is based on JavaScript which makes it easier to integrate with any other JavaScript library and runnable on browsers like IE, Opera, FF, Safari, Chrome etc.
6. Testing - AngularJS is designed to be testable so that you can test your AngularJS app components as easy as possible. It has dependency injection at its core, which makes it easy to test.

Source: github.com/krosti

Answer: In AngularJS services are the singleton objects or functions that are used for carrying out specific tasks. It holds some business logic and these function can be called as controllers, directive, filters and so on.

Source: github.com/krosti

Answer: During compilation process when specific HTML constructs are encountered a behaviour or function is triggered, this function is referred as directive. It is executed when the compiler encounters it in the DOM.

Different types of directives are:

• Element directives
• Attribute directives
• CSS class directives
• Comment directives

Source: guru99.com

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Answer:

• Avoid managing servers
• Flexible scaling by demand
• Pay for time and resources it takes to execute your code

Answer: By creating a cloud service, you can deploy a multi-tier web application in Azure, defining multiple roles to distribute processing and allow flexible scaling of your application. A cloud service consists of one or more web roles and/or worker roles, each with its own application files and configuration. Azure Websites and Virtual Machines also enable web applications on Azure. The main advantage of cloud services is the ability to support more complex multi-tier architectures

Source: mindmajix.com

Answer: A web role provides a dedicated Internet Information Services (IIS) web-server used for hosting front-end web applications.

Source: mindmajix.com

Answer: Azure Functions is a solution for easily running small pieces of code, or "functions," in the cloud. We can write just the code we need for the problem at hand, without worrying about a whole application or the infrastructure to run it and use language of our choice such as C#, F#, Node.js, Java, or PHP. Azure Functions lets us develop serverless applications on Microsoft Azure.

Answer: Serverless computing is the abstraction of servers, infrastructure, and operating systems. When you build serverless apps you don’t need to provision and manage any servers, so you can take your mind off infrastructure concerns. Serverless computing is driven by the reaction to events and triggers happening in near-real-time—in the cloud.

As a fully managed service, server management and capacity planning are invisible to the developer and billing is based just on resources consumed or the actual time your code is running.

Answer: Resource groups (RG) in Azure is an approach to group a collection of assets in logical groups for easy or even automatic provisioning, monitoring, and access control, and for more effective management of their costs. The underlying technology that powers resource groups is the Azure Resource Manager (ARM).

Source: onlinetech.com

Answer: Every Azure App Service web application includes a "hidden" service site called Kudu.

Kudu Console for example is a debugging service for Azure platform which allows you to explore your web app and surf the bugs present on it, like deployment logs, memory dump, and uploading files to your web app, and adding JSON endpoints to your web apps, etc.

Answer: A role instance is a virtual machine on which the application code and role configuration run. A role can have multiple instances, defined in the service configuration file.

Source: mindmajix.com

Answer: The guest operating system for a cloud service is the operating system installed on the role instances (virtual machines) on which your application code runs.

Source: mindmajix.com

Answer: Azure Blob storage is Microsoft's object storage solution for the cloud. Blob storage is optimized for storing massive amounts of unstructured data, such as text or binary data. Azure Storage offers three types of blobs:

• Block blobs store text and binary data, up to about 4.7 TB. Block blobs are made up of blocks of data that can be managed individually.
• Append blobs are made up of blocks like block blobs, but are optimized for append operations. Append blobs are ideal for scenarios such as logging data from virtual machines.
• Page blobs store random access files up to 8 TB in size. Page blobs store the VHD files that back VMs.

Source: docs.microsoft.com

Answer:

• Add the assembly to the BIN directory using KUDU
• Include the assembly and code the Azure Function to use it
• Add the using declaration so that the methods within the DLL can be accessed.

#r "D:\home\site\wwwroot\GreetingsAssemblyReference\bin\benjamin.dll"

using benjamin;

Answer: Azure Table storage is a service that stores structured NoSQL data in the cloud, providing a key/attribute store with a schemaless design.

Source: docs.microsoft.com

Answer: A Windows Azure subscription grants you access to Windows Azure services and to the Windows Azure Platform Management Portal. A Windows Azure subscription has two aspects:

• The Windows Azure account, through which resource usage is reported
• Services are billed.

Source: blogs.msdn.microsoft.com

Answer: The Azure Resource Manager (ARM) is the service used to provision resources in your Azure subscription. It was first announced at Build 2014 when the new Azure portal ( portal.azure.com) was announced and provides a new set of API's that are used to provision resources. The ARM is:

• Template-driven – Using templates to deploy all resources.
• Declarative – You declare the resources you want to have instead of imperative where you need to make rules.
• Idempotent – You can deploy the template over and over again without affecting the current state of resources.
• Multi-service – All services can be deployed using Azure Resource Manager, Website, Storage, VMs etc.
• Multi region - You can choose in which region you would like to deploy the resources.
• Extensible – Azure Resource Manager is extensible with more resource providers and thus resources.

Source: azurestack.blog

Answer: An Azure Resource Template is a JSON file used to deploy resources with Azure Resource Manager. It defines:

• Parameters
• Variables
• Resources - the actual resources that you are going to deploy or update
• Outputs

Source: onlinetech.com

Answer: A cloud service role is comprised of application files and a configuration. A cloud service can have two types of roles:

• web role
• worker role

Source: mindmajix.com

Answer: Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker. Azure Redis Cache is based on the popular open-source Redis cache. It gives you access to a secure, dedicated Redis cache, managed by Microsoft, and accessible from any application within Azure. It supports data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs and geospatial indexes with radius queries.

Source: quora.com

Answer: Azure Service Fabric is a distributed systems platform that makes it easy to package, deploy, and manage scalable and reliable micro-services. Service Fabric also addresses the significant challenges in developing and managing cloud applications. Developers and administrators can avoid complex infrastructure problems and focus on implementing mission-critical, demanding workloads that are scalable, reliable, and manageable. Service Fabric represents the next-generation middleware platform for building and managing these enterprise-class, tier-1, cloud-scale applications.

Source: quora.com

Answer: Azure AD gives you an easy and secure way to connect to the web applications you choose. You can access these applications in the same way you access your SaaS apps in Azure AD, no need for a VPN to change your network infrastructure.

Source: quora.com

Answer: Key Vault help you safeguard cryptographic keys and other secrets used by your applications whenever they are On-Premise or in the cloud. More and more services on Azure are now integrating Azure Key Vault as their secret/key source for things like deployments, data or even disk encryption.

Source: codeisahighway.com

Answer: A container organizes a set of blobs, similar to a folder in a file system. All blobs reside within a container. A storage account can contain an unlimited number of containers, and a container can store an unlimited number of blobs.

Source: docs.microsoft.com

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Answer:

Answer:

Answer: The interviewer is looking for similar things whether asking about company or position. The hiring manager wants to:

• Learn about your career goals and how this position fits into your plan
• Make sure that you are sincerely interested in the job and will be motivated to perform if hired
• Find out what you know about the company, industry, position (and if you took the time to research)
• Understand your priorities and preferences — which aspects of the company and/or job are appealing to you and why?

Source: github.com/yangshun/tech-interview-handbook

Answer: Here are some things your interviewer is likely looking for:

• Did you leave for a good reason?
• Did you leave voluntarily?
• Did you leave on good terms?
• What are your work values?

Source: biginterview.com

Answer:

Source: startups.co

Answer:

Source: github.com/yangshun/tech-interview-handbook

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Answer: Bootstrap is a platform for web development that is based on front-end framework and creates exceptional responsive designs. It is fast, easy and has multiple templates designed using HTML, and CSS. These templates are used for forms, tables, buttons, typography, modals, tables, navigation, carousels and images. Bootstrap also has Javascript plugins, which are optional. Bootstrap is preferred for developing mobile web applications.

Source: medium.com/@onlineinerview

Answer: Bootstrap is CSS/Javascript framework for building the rich web applications with minimal effort. This framework emphasis more on building mobile web applications.

Source: medium.com/@alisonbenhar

Answer: There are two simple ways to display a code in Bootstrap:

• <code> tag: In case you wish to display an inline code
• <pre> tag: In case you have a code with several lines or even a block element

Source: medium.com/@onlineinerview

Answer: In Bootstrap there are two types of Layout available

• Fluid Layout: Fluid layout is used when you want to create a app that is 100% wide and use up all the width of the screen
• Fixed Layout: For a standard screen you will use fixed layout (940 px) option

Source: medium.com/@alisonbenhar

Answer: Consider:

<ul class="list-unstyled">
  <li>Item 1</li>
  <li>Item 2</li>
    <ul>
      <li>Nested item 2.1</li>
      <li>Nested item 2.2</li>
      <li>Nested item 2.3</li>
    </ul>     
  <li>Item 3</li>
</ul>

What will be the output of the following HTML code?

Answer:

If we apply .list-unstyled to a list, it will remove the default list-style and left margin on the list items. But only for the immediate children. Main list items will be without any style, and nested list items will still have default unordered nested list-style.

Source: toptal.com

Answer: Bootstrap has features that are way better than other web development platforms. It provides an extensive browser support for almost every known browser such as Opera, Chrome, Firefox, Safari etc. With adequate knowledge of CSS and HTML, web development becomes easy on Bootstrap. Also, it supports mobile applications with the help of responsive design. It can adjust CSS as per the device, screen size etc. Instead of creating multiple files, it creates only a single file, which reduces any extra effort by the developer.

Source: medium.com/@onlineinerview

Answer: In total, there are five key components of Bootstrap i.e. CSS (multiple CSS files), **Scaffolding (**essential for the basic system that consist of Grid system, background and link styles), Layout Components: (shares a list of all layouts), JavaScript Plugins (includes jQuery and JavaScript plugins) and **Customization **(Allows customization of all components for a desired framework)

Source: medium.com/@onlineinerview

Answer: There are two major layouts for Bootstrap i.e. Fluid Layout and Fixed Layout. Fluid layout is necessary for creating an app that is 100 % wider and covers all the screen width. Fixed Layout is used only for a standard screen (940px). Both layouts can be used for creating a responsive design.

Source: medium.com/@onlineinerview

Answer: Jumbotron has a very basic function in bootstrap i.e. highlighting a content. It could either be a slogan/uvp (unique value proposition) or probably a headline. It increases the heading size and gives a margin for content of the landing page. In order to implement Jumbotron in a Bootstrap use:

 <div class=”jumbotron”>

Jumbotron can have any valid HTML along with other functions and classes.

Source: medium.com/@onlineinerview

Answer: Bootstrap is a sleek, intuitive, and powerful mobile first front-end framework for faster and easier web development. It uses HTML, CSS and Javascript.

Source: medium.com/@alisonbenhar

Answer: There are few reason why we choose Bootstrap for building websites

• Mobile Support: For mobile devices it provides full support in one single file rather than in separate file. It supports the responsive design including adjusting the CSS based on the different types of device, size of the screen etc. It reduces extra effort for developers.
• Easy to learn: Writing application in bootstrap is easy if you know CSS and HTML
• Browser Support: It supports all the popular browsers like Firefox, Opera, Safari, IE etc.

Source: medium.com/@alisonbenhar

Answer: Bootstrap sets the global default font-size to 14px, with a line-height of 1.428. The default font is changed to Helvetica and Arial with sans serif fallback.

All these styles are applied to the <body> and all paragraphs, with the addition that <p> (paragraphs) receive a bottom margin of half their computed line-height, which is 10px by default.

Source: toptal.com

Answer: There are several styling navigation elements available on bootstrap and every style uses the same function i.e. class .nav. In order to create tabs or a tabular navigation, you can begin with a simple or rather basic unordered list using the function class .nav. To add the tabs the function class .nav-tabs can be used.

Source: medium.com/@onlineinerview

Answer: Glyphicons are icon fonts which you can use in your web projects. Glyphicons Halflings are not free and require licensing, however their creator has made them available for Bootstrap projects free of cost.

To use the icons, simply use the following code just about anywhere in your code. Leave a space between the icon and text for proper padding.

<span class="glyphicon glyphicon-search"></span>

Source: medium.com/@alisonbenhar

Answer: To add some emphasis to a paragraph, add class .lead. This will give you larger font size, lighter weight, and a taller line height.

Source: medium.com/@alisonbenhar

Answer: Bootstrap sets a basic global display (background), typography, and link styles:

• Basic Global display − sets background-color: #fff; on the
• Typography − uses the @font-family-base, @font-size-base, and @line-height-base attributes as the typographic base
• Link styles − sets the global link color via attribute @link-color and apply link underlines only on :hover.

Source: medium.com/@alisonbenhar

Answer: Bootstrap 3 allows to make the images responsive by adding a class .img-responsive to the <img> tag. This class applies max-width: 100%; and height: auto; to the image so that it scales nicely to the parent element.

Source: medium.com/@alisonbenhar

Answer: Consider:

<button type="button" class="btn btn-default" data-toggle="tooltip" data-placement="top" title="Example tooltip">Hover over me</button>

What is missing for a tooltip to show properly?

Answer

Bootstrap’s Tooltip plugin is not CSS-only, like other plugins are. For performance reasons, the Tooltip plugin is opt-in, and to use it you must initialize it using JavaScript with the following example code:

$(function () {
  $('[data-toggle="tooltip"]').tooltip();
});

Source: medium.com/@alisonbenhar

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Answer: Using the inline style attribute on an element

<div>
    <p style="color: maroon;"></p>
</div>

Using a <style> block in the <head> section of your HTML

<head>
    <title>CSS Refresher</title>
    <style>
        body {
            font-family: sans-serif;
            font-size: 1.2em;
        }
    </style>
</head>

Loading an external CSS file using the <link> tag

<head>
    <title>CSS Refresher</title>
    <link rel="stylesheet" href="/css/styles.css" />
</head>

Source: goskills.com

Answer: CSS stands for Cascading Style Sheets. CSS is used to define styles for your web pages, including the design, layout and variations in display for different devices and screen sizes.

CSS was intended to allow web professionals to separate the content and structure of a website's code from the visual design.

Source: w3schools.com

Answer: The Document Object Model (DOM) is a cross-platform and language-independent application programming interface that treats an HTML, XHTML, or XML document as a tree structure wherein each node is an object representing a part of the document.

With the Document Object Model, programmers can create and build documents, navigate their structure, and add, modify, or delete elements and content. The DOM specifies interfaces which may be used to manage XML or HTML documents.

When a browser displays a document, it must combine the document's content with its style information. The browser converts HTML and CSS into the DOM (Document Object Model). The DOM represents the document in the computer's memory. It combines the document's content with its style.

Source: en.wikipedia.org

Answer: The CSS box model is a rectangular layout paradigm for HTML elements that consists of the following:

• Content - The content of the box, where text and images appear
• Padding - A transparent area surrounding the content (i.e., the amount of space between the border and the content)
• Border - A border surrounding the padding (if any) and content
• Margin - A transparent area surrounding the border (i.e., the amount of space between the border and any neighboring elements)

Source: toptal.com

Answer: Web browsers apply CSS rules to a document to affect how they are displayed. A CSS rule is formed from:

• A set of properties, which have values set to update how the HTML content is displayed,
• A selector, which selects the element(s) you want to apply the updated property values to.

A set of CSS rules contained within a stylesheet determines how a webpage should look.

Source: developer.mozilla.org

Answer:

• Bootstrap - Slow release cycle. Bootstrap 4 has been in alpha for almost 2 years. Add a spinner button component, as it is widely used.
• Semantic UI - Source code structure makes theme customization extremely hard to understand. Its unconventional theming system is a pain to customize. Hardcoded config path within the vendor library. Not well-designed for overriding variables unlike in Bootstrap.
• Bulma - A lot of non-semantic and superfluous classes and markup required. Not backward compatible. Upgrading versions breaks the app in subtle manners.

Source: codeburst.io

Answer: Yes. Flexbox is mainly meant for 1-dimensional layouts while Grid is meant for 2-dimensional layouts.

Flexbox solves many common problems in CSS, such as vertical centering of elements within a container, sticky footer, etc. Bootstrap and Bulma are based on Flexbox, and it is probably the recommended way to create layouts these days. Have tried Flexbox before but ran into some browser incompatibility issues (Safari) in using flex-grow, and I had to rewrite my code using inline-blocks and math to calculate the widths in percentages, it wasn't a nice experience.

Grid is by far the most intuitive approach for creating grid-based layouts (it better be!) but browser support is not wide at the moment.

Source: codeburst.io

Answer:

• IDs — Meant to be unique within the document. Can be used to identify an element when linking using a fragment identifier. Elements can only have one id attribute.

• Classes — Can be reused on multiple elements within the document. Mainly for styling and targeting elements.

Source: codeburst.io

Answer: Float is a CSS positioning property. Floated elements remain a part of the flow of the web page. This is distinctly different than page elements that use absolute positioning. Absolutely positioned page elements are removed from the flow of the webpage.

#sidebar {
  float: right; // left right none inherit			
}

The CSS clear property can be used to be positioned below left/right/both floated elements.

Source: css-tricks.com

Answer: CSS sprites combine multiple images into one single larger image. It is commonly used technique for icons (Gmail uses it).

• Use a sprite generator that packs multiple images into one and generate the appropriate CSS for it.
• Each image would have a corresponding CSS class with background-image, background-position and background-size properties defined.
• To use that image, add the corresponding class to your element.

Advantages:

• Reduce the number of HTTP requests for multiple images (only one single request is required per spritesheet). But with HTTP2, loading multiple images is no longer much of an issue.
• Advance downloading of assets that won’t be downloaded until needed, such as images that only appear upon :hover pseudo-states. Blinking wouldn't be seen.

Source: codeburst.io

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Details: You will be given 2 parameters: a low and high number. Your goal is to print all numbers between low and high, and for each of these numbers print whether or not the number is divisible by 3. If the number is divisible by 3, print the word "div3" directly after the number.

Answer: We'll solve this problem by first creating a loop that will print each number from low to high. Once we have the code for that written, we'll add a conditional that will check if the number is evenly divisible by 3 by using the mod operator.

function test_divisors(low, high) {
  
  // we'll store all numbers and strings within an array
  // instead of printing directly to the console
  var output = [];
  
  for (var i = low; i <= high; i++) {
    
    // simply store the current number in the output array
    output.push(i);
    
    // check if the current number is evenly divisible by 3
    if (i % 3 === 0) { output.push('div3'); }
    
  }
  
  // return all numbers and strings
  return output;
  
}

test_divisors(2, 10);

Source: coderbyte.com

Details: Write a function that takes an array of integers and returns the sum of the integers after adding 1 to each.

Answer:

// ES5 method is nice and clean
exports.es5 = function (array) {
  return array.reduce(function (memo, num) {
    return memo + num;
  }, array.length);
};

// Without array.reduce method isn't much different
exports.iterative = function (array) {
  var result = array.length;

  for (var i = 0; i < array.length; i++) {
    result += array[i];
  }

  return result;
};

Source: github.com/blakeembrey

Details: Find out if a string is a rotation of another string. E.g. ABCD is a rotation of BCDA but not ACBD.

Answer: First make sure a and b are of the same length. Then check to see if b is a substring of a concatenated with a:

module.exports = function (a, b) {
  return a.length === b.length && (a + a).indexOf(b) > -1;
};

Source: github.com/blakeembrey

Details: Write a function called oddball_sum which takes in a list of numbers and returns the sum of all the odd elements. Try to solve with and without reduce function.

Answer: To solve this challenge we'll simply loop through the array while maintaining a final count, and every time an odd number is encountered we'll add it to the count.

Without reduce:

function oddball_sum(nums) {
 
  // final count of all odd numbers added up
  var final_count = 0;
  
  // loop through entire list
  for (var i = 0; i < nums.length; i++) {
    
    // we divide by 2, and if there is a remainder then
    // the number must be odd so we add it to final_count
    if (nums[i] % 2 === 1) {
      final_count += nums[i]
    }
    
  }
  
  return final_count;
  
}

oddball_sum([1, 2, 3, 4, 5]); 

With reduce:

function oddball_sum(nums) {
  return nums.reduce(function(total, item){
  	if (item % 2 === 1) {
  		return total += item;
  	}
  	return total;
  });
}

Source: prepwork.appacademy.io

Details: You will be given a number N that represents where the minute hand currently is on a clock. Your program should return the angle that is formed by the minute hand and the 12 o'clock mark on the clock.

Answer: If the input is 15 then your program should return 90 because a 90-degree angle is formed by the minute hand and the 12 o'clock mark on the clock. We'll solve this challenge by first calculating what angle is created by each minute passing on a clock. Once we calculate this number, we multiply it by the input to determine the final angle.

A method to solve such problems is to consider the rate of change of the angle in degrees per minute. The hour hand of a normal 12-hour analogue clock turns 360° in 12 hours (720 minutes) or 0.5° per minute. The minute hand rotates through 360° in 60 minutes or 6° per minute.

function simpleClockAngle(num) {

  // we got 6 because 360/60 = 6
  // 360 represents the full number of a degrees in a circle and
  // 60 is the number of minutes on a clock, so dividing these two numbers
  // gives us the number of degrees for one minute
  return 6 * num;

}

simpleClockAngle(15);

Source: coderbyte.com

Details: You will be given an array of several arrays that each contain integers and your goal is to write a function that will sum up all the numbers in all the arrays. For example, if the input is [[3, 2], [1], [4, 12]] then your program should output 22 because 3 + 2 + 1 + 4 + 12 = 22. Solve without and with reduce.

Answer: We will solve this challenge by looping through the entire array, and then looping through each inner array adding up all the numbers.

function sum_array(arr) {
  // store our final answer
  var sum = 0;
  // loop through entire array
  for (var i = 0; i < arr.length; i++) {
    // loop through each inner array
    for (var j = 0; j < arr[i].length; j++) {
      // add this number to the current final sum
      sum += arr[i][j];
    }
  }
  
  return sum;
}

sum_array([[3, 2], [1], [4, 12]]);

With reduce:

function sumArray(arr) {
  return arr.reduce((t, e) => t.concat(e)).reduce((t, e) => t + e)
}

Source: coderbyte.com

Details: Write a function called lucky_sevens which takes an array of integers and returns true if any three consecutive elements sum to 7.

Answer: To solve this challenge we'll simply loop through the array starting at the 3rd position, and checking if the number at this index plus the two previous elements sums to 7. We continue doing this as we loop through the entire array. Once we find three elements that sum to 7, we simply return true. If we reach the end of the array without finding elements that sum to 7, we return false.

function lucky_sevens(arr) {
  
  // if less than 3 elements then this challenge is not possible
  if (arr.length < 3) {
    return "not possible";
  }
  
  // because we know there are at least 3 elements we can
  // start the loop at the 3rd element in the array (i=2)
  // and check it along with the two previous elements (i-1) and (i-2)
  for (var i = 2; i < arr.length; i++) {
    if (arr[i] + arr[i-1] + arr[i-2] === 7) {
      return true; 
    }
  }
  
  // if loop is finished and no elements summed to 7
  return false;
  
}

lucky_sevens([2, 1, 5, 1, 0]);

Source: coderbyte.com

Details: Given an integer x and a sorted array a of N distinct integers, design a linear-time algorithm to determine if there exists two distinct indices i and j such that a[i] + a[j] == x

For example, if the array is [3, 5, 2, -4, 8, 11] and the sum is 7, your program should return [[11, -4], [2, 5]] because 11 + -4 = 7 and 2 + 5 = 7.

Answer: The algorithm below makes use of hash tables which have a constant lookup time. As we pass through each element in the array, we check to see if S minus the current element exists in the hash table. We only need to loop through the array once, resulting in a running time of O(n) since each lookup and insertion in a hash table is O(1).

// our two sum function which will return
// all pairs in the array that sum up to S
function twoSum(arr, S) {

  var sums = [];
  var hashTable = {};

  // check each element in array
  for (var i = 0; i < arr.length; i++) {
 
    // calculate S - current element
    var sumMinusElement = S - arr[i];

    // check if this number exists in hash table
    // if so then we found a pair of numbers that sum to S
    if (hashTable[sumMinusElement.toString()] !== undefined) { 
      sums.push([arr[i], sumMinusElement]);
    }

    // add the current number to the hash table
    hashTable[arr[i].toString()] = arr[i];

  }

  // return all pairs of integers that sum to S
  return sums;

}

twoSum([3, 5, 2, -4, 8, 11], 7);

Source: coderbyte.com

Answer: We will store a reference to the front and back of the queue in order to make enqueuing and dequeuing run in O(1) constant time. Every time we want to insert into the queue, we add the new element to the end of the linked list and update the back pointer. When we want to dequeue we return the first node in the linked list and update the front pointer.

// queue is initially empty
var Queue = {front: null, back: null};

// we will use a node to keep track of the elements
// in the queue which is represented by a linked list
function Node(data, next) {
  this.data = data;
  this.next = next;
} 

// add elements to queue in O(1) time
function Enqueue(element) {
  var N = new Node(element, null);
  if (Queue.back === null) {
    Queue.front = N;
    Queue.back = N; 
  } else { 
    Queue.back.next = N; 
    Queue.back = Queue.back.next;
  } 
}

// remove first element from queue in O(1) time
function Dequeue() {
  if (Queue.front !== null) { 
    var first = Queue.front;
    Queue.front = Queue.front.next; 
    return first.data;
  } else {
    if (Queue.back !== null) { Queue.back = null; }
    return 'Cannot dequeue because queue is empty';
  }
}

Enqueue('a'); 
Enqueue('b'); 
Enqueue('c'); 
Dequeue();

Source: codeisahighway.com

Details: Given a binary tree of integers, print it in level order. The output will contain space between the numbers in the same level, and new line between different levels.

Answer:

module.exports = function (root) {
  // Doing a breadth first search using recursion.
  (function walkLevel (children) {
    // Create a new queue for the next level.
    var queue = [],
        output;

    // Use the map function to easily join all the nodes together while pushing
    // it's children into the next level queue.
    output = children.map(function (node) {
      // Assuming the node has children stored in an array.
      queue = queue.concat(node.children || []);
      return node.value;
    }).join(' ');

    // Log the output at each level.
    console.log(output);

    // If the queue has values in it, recurse to the next level and walk
    // along it.
    queue.length && walkLevel(queue);
  })([root]);
};

Source: ardendertat.com

Details: You will be given a list of stock prices for a given day and your goal is to return the maximum profit that could have been made by buying a stock at the given price and then selling the stock later on.

For example if the input is:

[45, 24, 35, 31, 40, 38, 11] 

then your program should return 16 because if you bought the stock at $24 and sold it at $40, a profit of $16 was made and this is the largest profit that could be made. If no profit could have been made, return -1.

Answer: We'll solve the challenge the following way:

1. Iterate through each number in the list.
2. At the ith index, get the i+1 index price and check if it is larger than the ith index price.
3. If so, set buy_price = i and sell_price = i+1. Then calculate the profit: sell_price - buy_price.
4. If a stock price is found that is cheaper than the current buy_price, set this to be the new buying price and continue from step 2.
5. Otherwise, continue changing only the sell_price and keep buy_price set.

This algorithm runs in linear time, making only one pass through the array, so the running time in the worst case is O(n).

function StockPicker(arr) { 
  
  var max_profit = -1;
  var buy_price = 0;
  var sell_price = 0;
  
  // this allows our loop to keep iterating the buying
  // price until a cheap stock price is found
  var change_buy_index = true;
  
  // loop through list of stock prices once
  for (var i = 0; i < arr.length-1; i++) {
    
    // selling price is the next element in list
    sell_price = arr[i+1]; 
    
    // if we have not found a suitable cheap buying price yet
    // we set the buying price equal to the current element
    if (change_buy_index) { buy_price = arr[i]; }
    
    // if the selling price is less than the buying price
    // we know we cannot make a profit so we continue to the 
    // next element in the list which will be the new buying price
    if (sell_price < buy_price) {
      change_buy_index = true; 
      continue;
    }
    
    // if the selling price is greater than the buying price
    // we check to see if these two indices give us a better 
    // profit then what we currently have
    else { 
      var temp_profit = sell_price - buy_price;
      if (temp_profit > max_profit) { max_profit = temp_profit; }
      change_buy_index = false;
    }
    
  }
  
  return max_profit;
         
}

StockPicker([44, 30, 24, 32, 35, 30, 40, 38, 15]);  

Source: coderbyte.com

Details: Given a text file and a word, find the positions that the word occurs in the file. We’ll be asked to find the positions of many words in the same file.

Answer: Since we’ll have to answer multiple queries, precomputation would be useful. We’ll build a data structure that stores the positions of all the words in the text file. This is known as inverted index.

module.exports = function (text) {
  var trie   = {},
      pos    = 0,
      active = trie; // Start the active structure as the root trie structure

  // Suffix a space after the text to make life easier
  text += ' ';

  // Loop through the input text adding it to the trie structure
  for (var i = 0; i < text.length; i++) {
    // When the character is a space, restart
    if (text[i] === ' ') {
      // If the current active doesn't equal the root, set the position
      if (active !== trie) {
        (active.positions = active.positions || []).push(pos);
      }
      // Reset the positions and the active part of the data structure
      pos    = i;
      active = trie;
      continue;
    }

    // Set the next character in the structure up
    active[text[i]] = (active[text[i]] || {});
    active = active[text[i]];
  }

  // Return a function that accepts a word and looks it up in the trie structure
  return function (word) {
    var i      = -1,
        active = trie;

    while (word[++i]) {
      if (!active[word[i]]) { return []; }
      active = active[word[i]];
    }

    return active.positions;
  };
};

Source: github.com/blakeembrey

Details: You will be given an array with 5 numbers. The first 2 numbers represent a range, and the next two numbers represent another range. The final number in the array is X. The goal of your program is to determine if both ranges overlap by at least X numbers. For example, in the array [4, 10, 2, 6, 3] the ranges 4 to 10 and 2 to 6 overlap by at least 3 numbers (4, 5, 6), so your program should return true. Solve with and without looping.

If the array is [10, 20, 4, 14, 4] then the ranges are:

10 11 12 13 14 15 16 17 18 19 20
4 5 6 7 8 9 10 11 12 13 14

These ranges overlap by at least 4 numbers, namely: 10, 11, 12, 13, 14 so your program should return true.

Answer: With loop:

function OverlappingRanges(arr) {

  // keep a count of how many numbers overlap
  var counter = 0;
  
  // loop through one of the ranges
  for (var i = arr[0]; i < arr[1]; i++) {

    // check if a number within the first range exists
    // in the second range
    if (i >= arr[2] && i <= arr[3]) { 
      counter += 1;
    }

  }
 
  // check if the numbers that overlap is equal to or greater
  // than the last number in the array
  return (counter >= arr[4]) ? true : false;
}

OverlappingRanges([4, 10, 2, 6, 3]); 

Without loop:

function overlapping(input){
  var nums1 = listOfNums(input[0], input[1]);
  var nums2 = listOfNums(input[2], input[3]);
  var overlappingNum = 0;

  if(nums1[0] >= nums2[0] && nums1[0] <= nums2[1]){
    overlappingNum =  nums2[1] - nums1[0] + 1;
  } else {
    overlappingNum =  nums1[1] - nums2[0] + 1;
  }
  if(overlappingNum >= input[4]){
    return true;
  }
}

function listOfNums(a, b){
  var start = a;
  var end = b;
  if(a > b){
    start = b;
    end = a;
  }

  return [a, b];
}

var a = [4, 10, 2, 6, 3];
overlapping(a)

Source: coderbyte.com

Details: Write a function that accepts a function and timeout, x, in number of milliseconds. It returns a function that can only be executed once per x milliseconds. This can be useful for limiting the number of time and computation heavy function that are run. For example, making AJAX requests to an autocompletion API.

Once written, add a third parameter that will allow the function to be executed immediately if set to true. Otherwise the function will run at the end of the timeout period.

Answer:

module.exports = function (fn, delay, execAsap) {
  var timeout; // Keeps a reference to the timeout inside the returned function

  return function () {
    // Continue to pass through the function execution context and arguments
    var that = this,
        args = arguments;

    // If there is no timeout variable set, proceed to create a new timeout
    if (!timeout) {
      execAsap && fn.apply(that, args);

      timeout = setTimeout(function () {
        execAsap || fn.apply(that, args);
        // Remove the old timeout variable so the function can run again
        timeout = null;
      }, delay || 100);
    }
  };
};

Source: github.com/blakeembrey

Details: For this problem, your goal is to sort an array of 0, 1, 2 but you must do this in place, in linear time and without any extra space (such as creating an extra array). This is called the Dutch national flag sorting problem. For example, if the input array is [2,0,0,1,2,1] then your program should output [0,0,1,1,2,2] and the algorithm should run in O(n) time.

Answer: The solution to this algorithm will require 3 pointers to iterate throughout the array, swapping the necessary elements.

1. Create a low pointer at the beginning of the array and a high pointer at the end of the array.
2. Create a mid pointer that starts at the beginning of the array and iterates through each element.
3. If the element at arr[mid] is a 2, then swap arr[mid] and arr[high] and decrease the high pointer by 1.
4. If the element at arr[mid] is a 0, then swap arr[mid] and arr[low] and increase the low and mid pointers by 1.
5. If the element at arr[mid] is a 1, don't swap anything and just increase the mid pointer by 1.

function swap(arr, i1, i2) {
  var temp = arr[i1];
  arr[i1] = arr[i2];
  arr[i2] = temp;
}

function dutchNatFlag(arr) {
  
  var low = 0;
  var mid = 0;
  var high = arr.length - 1;
  
  // one pass through the array swapping
  // the necessary elements in place
  while (mid <= high) {
    if      (arr[mid] === 0) { swap(arr, low++, mid++); }
    else if (arr[mid] === 2) { swap(arr, mid, high--); }
    else if (arr[mid] === 1) { mid++; }
  }
  
  return arr;
  
}

dutchNatFlag([2,2,2,0,0,0,1,1]); 

Source: coderbyte.com

Details:

Suppose you want climb a staircase of N steps, and on each step you can take either 1 or 2 steps. How many distinct ways are there to climb the staircase? For example, if you wanted to climb 4 steps, you can take the following distinct number of steps:

1) 1, 1, 1, 1
2) 1, 1, 2
3) 1, 2, 1
4) 2, 1, 1
5) 2, 2

So there are 5 distinct ways to climb 4 steps. We want to write a function, using recursion, that will produce the answer for any number of steps.

Answer: The solution to this problem requires recursion, which means to solve for a particular N, we need the solutions for previous N's. The solution for N steps is equal to the solutions for N - 1 steps plus N - 2 steps.

function countSteps(N) {
  
  // just as in our solution explanation above, we know that to climb 1 step
  // there is only 1 solution, and for 2 steps there are 2 solutions
  if (N === 1) { return 1; }
  if (N === 2) { return 2; }
  
  // for all N > 2, we add the previous (N - 1) + (N - 2) steps to get
  // an answer recursively
  return countSteps(N - 1) + countSteps(N - 2);
  
}

// the solution for N = 6 will recursively be solved by calculating
// the solution for N = 5, N = 4, N = 3, and N = 2 which we know is 2
countSteps(6); 

Source: coderbyte.com

Answer: The steps in the bubble sort algorithm are:

1. Loop through the whole array starting from index 1
2. If the number in the array at index i-1 is greater than i, swap the numbers and continue
3. Once the end of the array is reached, start looping again from the beginning
4. Once no more elements can be swapped, the sorting is complete

function swap(arr, i1, i2) {
  var temp = arr[i1];
  arr[i1] = arr[i2];
  arr[i2] = temp;
}

function bubblesort(arr) {
  
  var swapped = true;
  
  // keep going unless no elements can be swapped anymore
  while (swapped) {
    
    // set swapped to false so that the loop stops
    // unless two element are actually swapped
    swapped = false;

    // loop through the whole array swapping adjacent elements
    for (var i = 1; i < arr.length; i++) {
      if (arr[i-1] > arr[i]) {
        swap(arr, i-1, i);
        swapped = true;
      }
    }
    
  }
  
  return arr;
         
}

bubblesort([103, 45, 2, 1, 97, -4, 67]); 

Source: coderbyte.com

Answer: Suppose we push a, b, c to a stack. If we are trying to implement a queue and we call the dequeue method 3 times, we actually want the elements to come out in the order: a, b, c, which is in the opposite order they would come out if we popped from the stack. So, basically, we need to access the elements in the reverse order that they exist in the stack.

Algorithm for queue using two stacks:

1. When calling the enqueue method, simply push the elements into the stack 1.
2. If the dequeue method is called, push all the elements from stack 1 into stack 2, which reverses the order of the elements. Now pop from stack 2.

The worst case running time for implementing these operations using stacks is O(n) because you need to transfer n elements from stack 1 to stack 2 when a dequeue method is called. Pushing to stack 1 is simply O(1).

// implement stacks using plain arrays with push and pop functions
var Stack1 = [];
var Stack2 = [];

// implement enqueue method by using only stacks
// and the push and pop functions
function Enqueue(element) {
  Stack1.push(element);
}

// implement dequeue method by pushing all elements
// from stack 1 into stack 2, which reverses the order
// and then popping from stack 2
function Dequeue() {
  if (Stack2.length === 0) {
    if (Stack1.length === 0) { return 'Cannot dequeue because queue is empty'; }
    while (Stack1.length > 0) {
      var p = Stack1.pop();
      Stack2.push(p);
    }
  }
  return Stack2.pop();
}

Enqueue('a');
Enqueue('b');
Enqueue('c');
Dequeue(); 

Source: coderbyte.com

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Answer: Data structure availability may vary by programming languages. Commonly available data structures are:

• list,
• arrays,
• stack,
• queues,
• graph,
• tree etc.

Source: tutorialspoint.com

Answer: Algorithm is a step by step procedure, which defines a set of instructions to be executed in certain order to get the desired output.

Source: tutorialspoint.com

Answer: Linear search or sequential search is a method for finding a target value within a list. It sequentially checks each element of the list for the target value until a match is found or until all the elements have been searched. Linear search runs in at worst linear time and makes at most n comparisons, where n is the length of the list.

• Worst-case performance O(n)
• Best-case performance O(1)
• Average performance O(n)
• Worst-case space complexity O(1) iterative

In theory other search algorithms may be faster than linear search (for instance binary search), in practice even on medium-sized arrays (around 100 items or less) it might be infeasible to use anything else.

Source: wikipedia.org

Answer: Asymptotic analysis of an algorithm, refers to defining the mathematical boundation/framing of its run-time performance. Using asymptotic analysis, we can very well conclude the best case, average case and worst case scenario of an algorithm.

Asymptotic analysis can provide three levels of mathematical binding of execution time of an algorithm:

• Best case is represented by Ω(n) notation.
• Worst case is represented by Ο(n) notation.
• Average case is represented by Θ(n) notation.

Source: tutorialspoint.com

Answer: A linear data-structure has sequentially arranged data items. The next item can be located in the next memory address. It is stored and accessed in a sequential manner. Array and list are example of linear data structure.

The following operations are commonly performed on any data-structure:

• Insertion − adding a data item
• Deletion − removing a data item
• Traversal − accessing and/or printing all data items
• Searching − finding a particular data item
• Sorting − arranging data items in a pre-defined sequence

Source: tutorialspoint.com

Answer: Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that repeatedly steps through the list to be sorted, compares each pair of adjacent items and swaps them if they are in the wrong order. The pass through the list is repeated until no swaps are needed, which indicates that the list is sorted.

Bubble sort has a worst-case and average complexity of О(n2), where n is the number of items being sorted. Most practical sorting algorithms have substantially better worst-case or average complexity, often O(n log n). Therefore, bubble sort is not a practical sorting algorithm.

Source: wikipedia.org

Answer: The below given problems find their solution using greedy algorithm approach:

• Travelling Salesman Problem
• Prim's Minimal Spanning Tree Algorithm
• Kruskal's Minimal Spanning Tree Algorithm
• Dijkstra's Minimal Spanning Tree Algorithm
• Graph - Map Coloring
• Graph - Vertex Cover
• Knapsack Problem
• Job Scheduling Problem

Source: tutorialspoint.com

Answer: The below given problems find their solution using divide and conquer algorithm approach:

• Merge Sort
• Quick Sort
• Binary Search
• Strassen's Matrix Multiplication
• Closest pair (points)

Source: tutorialspoint.com

Answer: The below given problems find their solution using divide and conquer algorithm approach:

• Fibonacci number series
• Knapsack problem
• Tower of Hanoi
• All pair shortest path by Floyd-Warshall
• Shortest path by Dijkstra
• Project scheduling

Source: tutorialspoint.com

Answer: In data-structure, stack is an Abstract Data Type (ADT) used to store and retrieve values in Last In First Out (LIFO) method.

Stacks follows LIFO method and addition and retrieval of a data item takes only Ο(n) time. Stacks are used where we need to access data in the reverse order or their arrival. Stacks are used commonly in recursive function calls, expression parsing, depth first traversal of graphs etc.

The below operations can be performed on a stack:

• push() − adds an item to stack
• pop() − removes the top stack item
• peek() − gives value of top item without removing it
• isempty() − checks if stack is empty
• isfull() − checks if stack is full

Source: tutorialspoint.com

Answer: Queue is an abstract data structure (ADS), somewhat similar to stack. In contrast to stack, queue is opened at both end. One end is always used to insert data (enqueue) and the other is used to remove data (dequeue). Queue follows First-In-First-Out (FIFO) methodology, i.e., the data item stored first will be accessed first.

As queues follows FIFO method, they are used when we need to work on data-items in exact sequence of their arrival. Every operating system maintains queues of various processes. Priority queues and breadth first traversal of graphs are some examples of queues.

The below operations can be performed on a queue:

• enqueue() − adds an item to rear of the queue
• dequeue() − removes the item from front of the queue
• peek() − gives value of front item without removing it
• isempty() − checks if stack is empty
• isfull() − checks if stack is full

Source: tutorialspoint.com

Answer:

• A linear search looks down a list, one item at a time, without jumping. In complexity terms this is an O(n) search - the time taken to search the list gets bigger at the same rate as the list does.

• A binary search is when you start with the middle of a sorted list, and see whether that's greater than or less than the value you're looking for, which determines whether the value is in the first or second half of the list. Jump to the half way through the sublist, and compare again etc. In complexity terms this is an O(log n) search - the number of search operations grows more slowly than the list does, because you're halving the "search space" with each operation.

Comparing the two:

• Binary search requires the input data to be sorted; linear search doesn't
• Binary search requires an ordering comparison; linear search only requires equality comparisons
• Binary search has complexity O(log n); linear search has complexity O(n)
• Binary search requires random access to the data; linear search only requires sequential access (this can be very important - it means a linear search can stream data of arbitrary size)

Source: wikipedia.org

Answer: A problem can be solved in more than one ways. So, many solution algorithms can be derived for a given problem. We analyze available algorithms to find and implement the best suitable algorithm.

An algorithm are generally analyzed on two factors − time and space. That is, how much execution time and how much extra space required by the algorithm.

Source: tutorialspoint.com

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Answer: The Design patterns can be classified into three main categories:

• Creational Patterns
• Behavioral Patterns
• Functional Patterns