30+ ABS India Interview Questions and Answers

Javascript is single threaded.

• Javascript has a single call stack and event loop.

• It can handle asynchronous operations through callbacks and promises.

• Web workers can be used for multi-threading in Javascript.

Prototype is a property of an object that allows adding new properties and methods to an existing object.

• Prototype is a blueprint for creating objects.

• It is used to add new properties and methods to an existing object.

• All objects in JavaScript have a prototype property.

• The prototype property is used to share properties and methods between objects.

• Modifying the prototype of an object affects all instances of that object.

Reverse array, get substring, remove 0s

• Use array.reverse() to reverse the array

• Use string.substring() to get a substring

• Use array.filter() to remove 0s from the array

Use Java Selenium code to validate new and old prices of mobile phones on Amazon.

• Use WebDriver to open Amazon website

• Locate the elements for new and old prices using XPath or CSS selectors

• Get the text of both elements and compare them to validate

Static keyword is used to create class-level variables and methods that can be accessed without creating an instance of the class.

• Static variables are shared among all instances of a class

• Static methods can be called without creating an object of the class

• Static blocks are used to initialize static variables

• Static import is used to import static members of a class

Event loop is a mechanism that allows JavaScript to perform non-blocking I/O operations.

• Event loop is a part of JavaScript runtime that continuously checks the call stack and the task queue.

• It executes the tasks in the task queue one by one, and once the task is completed, it is removed from the queue.

• Event loop ensures that the JavaScript code does not block the main thread and allows for asynchronous programming.

• Examples of asynchronous operations that use event loop are se...read more

Validating APIs using Rest Assured involves writing scripts to send requests and verify responses.

• Use Rest Assured library to send HTTP requests and validate responses

• Write test scripts using given(), when(), then() methods to set up request, send request, and validate response

• Verify status code, response body, headers, etc. in the script

• Use assertions to check expected values against actual values

Virtual DOM is a lightweight copy of the actual DOM that allows for efficient updates and rendering in web applications.

• Virtual DOM is a concept used in frameworks like React to improve performance by minimizing direct manipulation of the actual DOM.

• When changes are made to the virtual DOM, a comparison is done with the actual DOM to identify the minimal updates needed, reducing re-renders.

• This approach helps in optimizing rendering speed and improving user experience in web ...read more

var is function-scoped while let is block-scoped.

• var declarations are hoisted to the top of their scope while let declarations are not.

• var can be redeclared in the same scope while let cannot.

• let is preferred over var for better code readability and avoiding unexpected behavior.

• Example: var x = 10; if (true) { var x = 20; } console.log(x); // Output: 20 let y = 10; if (true) { let y = 20; } console.log(y); // Output: 10

Content type mismatch in an API occurs when the expected content type of a request or response does not match the actual content type.

• Occurs when the content type specified in the request headers does not match the content type of the data being sent or received

• Can lead to errors in processing the data or displaying it correctly

• For example, sending JSON data with a content type of 'application/xml' in the request headers

Java program to generate permutations and combinations of a given string

• Use recursion to generate permutations and combinations

• Create a function to swap characters in the string

• Use a HashSet to store unique permutations and combinations

Abstract class can have implementation while interface only has method signatures.

• Abstract class can have constructors while interface cannot.

• A class can implement multiple interfaces but can only extend one abstract class.

• Abstract classes can have non-abstract methods while interfaces cannot.

• Abstract classes can have instance variables while interfaces cannot.

• Interfaces can have default methods while abstract classes cannot.

Spring Boot is a framework for building standalone, production-grade Spring-based applications.

• Simplifies the process of creating and deploying Spring-based applications

• Provides a range of pre-configured features and dependencies

• Enables rapid development and prototyping

• Supports a variety of deployment options, including cloud-based platforms

• Offers a range of plugins and tools for development and testing

• Improves developer productivity and reduces time-to-market

Improving web application performance involves optimizing code, reducing network requests, and utilizing caching techniques.

• Optimize code by removing unnecessary code, using efficient algorithms, and minimizing DOM manipulation.

• Reduce network requests by combining files, using asynchronous loading, and implementing lazy loading.

• Utilize caching techniques such as browser caching, server-side caching, and CDN caching to reduce load times.

Code to print Fibonacci and Prime number

• For Fibonacci, use a loop to generate the sequence and print each number

• For Prime numbers, use a loop to check if each number is divisible by any number less than itself

• Combine the two loops to print both sequences

DependsOn Method in TestNG is used to specify the methods that this method depends on to run successfully.

• Allows to specify the methods that need to be executed before the current method

• If any of the methods specified in DependsOn fails, the current method will be skipped

• Helps in maintaining the order of test methods execution

Passing data from parent to child component in React

• Use props to pass data from parent to child component

• Define a prop in the parent component and pass it to the child component

• Access the prop in the child component using this.props

• Example:

Ionic build step to release Android and iOS

• To release an Ionic app for Android, use the command 'ionic cordova build android --release'

• To release an Ionic app for iOS, use the command 'ionic cordova build ios --release'

• For Android, you will need a keystore file and signing configuration

• For iOS, you will need a valid provisioning profile and certificate

List is an ordered collection while Set is an unordered collection of unique elements.

• List allows duplicate elements while Set does not.

• List maintains the insertion order while Set does not guarantee any order.

• List is implemented using ArrayList, LinkedList, etc. while Set is implemented using HashSet, TreeSet, etc.

• List has methods like get(), set(), add(), remove(), etc. while Set has methods like add(), remove(), contains(), etc.

Generics is a feature in Java that allows classes and methods to be parameterized by type.

• Generics provide type safety and reduce code duplication.

• They allow for the creation of reusable code.

• Example: List myList = new ArrayList();

• Example: public class MyClass { ... }

• Example: public void myMethod(T t) { ... }

API testing is a type of software testing that involves testing APIs directly, while Postman is a popular tool used for API testing.

• API testing involves testing the functionality, reliability, performance, and security of APIs

• Postman is a tool that allows developers to test APIs by sending requests and receiving responses

• Postman can be used to automate API testing, create test suites, and generate documentation

• API testing with Postman can help identify bugs, improve API desig...read more

Data-driven testing is a testing methodology where test input and output values are stored in data files or databases.

• Test cases are designed based on input and output data stored in external files or databases.

• Allows for easy maintenance and scalability of test cases by separating test data from test scripts.

• Helps in reusability of test scripts with different sets of data.

• Commonly used in automation testing to perform repetitive tests with multiple data sets.

• Example: Using a...read more

Different types of waits in Selenium include Implicit Wait, Explicit Wait, Fluent Wait, and Thread.sleep()

• Implicit Wait: waits for a certain amount of time before throwing an exception if the element is not found

• Explicit Wait: waits for a certain condition to occur before proceeding with the next step

• Fluent Wait: waits for a certain condition to occur with a polling frequency and timeout

• Thread.sleep(): pauses the execution for a specified amount of time

I have used design patterns like Singleton, Factory, Observer, and Strategy in my projects.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying the exact class of object that will be created.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

• Strategy pattern defines a f...read more

Code optimization involves improving the efficiency and performance of software by reducing resource usage and execution time.

• Identify and eliminate bottlenecks in the code

• Use efficient algorithms and data structures

• Minimize unnecessary computations and memory usage

• Optimize database queries and network communication

• Profile and analyze code to identify areas for improvement

HashMap is non-synchronized and allows null values, while HashTable is synchronized and does not allow null values.

• HashMap is non-synchronized, meaning it is not thread-safe, while HashTable is synchronized and thread-safe.

• HashMap allows null values for both keys and values, while HashTable does not allow null keys or values.

• HashMap is generally preferred for non-thread-safe applications, while HashTable is used in multi-threaded environments.

• Example: HashMap<String, Integer>...read more

Indexing in SQL is a technique to improve query performance by creating indexes on columns.

• Indexes are created on columns that are frequently used in WHERE, JOIN, and ORDER BY clauses.

• Indexes can be created using CREATE INDEX statement.

• Indexes can be unique or non-unique.

• Indexes can be clustered or non-clustered.

• Indexes can be dropped using DROP INDEX statement.

MVVM focuses on data binding and separation of concerns, while MVP focuses on the separation of concerns between the view and the presenter.

• MVVM stands for Model-View-ViewModel, where the ViewModel acts as an intermediary between the view and the model.

• MVVM uses data binding to automatically update the view when the ViewModel changes.

• MVP stands for Model-View-Presenter, where the presenter acts as an intermediary between the view and the model.

• MVP requires the view to have a ...read more

Joins are used in SQL to combine data from two or more tables based on a related column between them.

• Types of joins include inner join, left join, right join, and full outer join

• Inner join returns only the matching rows from both tables

• Left join returns all rows from the left table and matching rows from the right table

• Right join returns all rows from the right table and matching rows from the left table

• Full outer join returns all rows from both tables, with NULL values for n...read more

Use filter method instead of reduce method to reduce usage in array of strings.

• Use filter method to create a new array with all elements that pass a certain condition.

• Example: const filteredArray = array.filter(item => item.length > 5);

• Avoid using reduce method for simple filtering tasks to improve readability and performance.

Bug life cycle refers to the stages a bug goes through from discovery to resolution.

• Bug is discovered and reported

• Bug is assigned to a developer

• Developer reproduces the bug

• Developer fixes the bug

• Bug is retested by QA

• Bug is closed if fixed or reopened if not

Print duplicate values in an array

• Iterate through the array and use a hash map to track the frequency of each element

• Print the elements with a frequency greater than 1

Step time is the time taken for a system to reach a new steady state after a change, while sample time is the time interval between consecutive samples in a system.

• Step time is the time taken for a system to settle after a change in input.

• Sample time is the time interval between consecutive samples in a system.

• Step time is typically used in control systems to analyze system response.

• Sample time is important in signal processing for data acquisition and processing.

• Example: In ...read more

Recursively reverse a string by swapping characters at opposite ends.

• Create a base case for when the string length is 0 or 1.

• Recursively call the function with the substring excluding the first and last characters.

• Swap the first and last characters in each recursive call.

lazy is a property delegate that initializes the value only when accessed, while lateinit is a modifier that indicates a non-null property will be initialized before being accessed.

• lazy is used for properties that are expensive to initialize and may not be needed, while lateinit is used for properties that must be initialized before being accessed.

• lazy properties are initialized the first time they are accessed, while lateinit properties must be initialized before accessing t...read more