200+ WorldEmp Interview Questions and Answers

Hooks are a feature introduced in React 16.8 that allow developers to use state and other React features in functional components.

• useState() - for managing state in functional components

• useEffect() - for performing side effects in functional components

• useContext() - for accessing context in functional components

• useReducer() - for managing complex state and actions in functional components

• useCallback() - for memoizing functions in functional components

• useMemo() - for memoizing...read more

Higher Order Functions are functions that take other functions as arguments or return functions as their results.

• Higher Order Functions can be used to create reusable code by abstracting common functionality into a separate function.

• They can also be used to implement functional programming concepts like currying and composition.

• Example: Array.prototype.map() is a higher order function that takes a callback function as an argument and applies it to each element of an array, re...read more

Event Loop is a mechanism that allows JavaScript to handle asynchronous operations.

• Event Loop is a continuous process that checks the Event Queue and moves events to the Event Stack.

• Event Queue holds all the events that are waiting to be processed.

• Event Stack holds the events that are currently being processed.

• When the Event Stack is empty, the Event Loop checks the Event Queue for new events.

• JavaScript uses Event Loop to handle asynchronous operations like setTimeout(), setI...read more

I have implemented various software applications on Linux OS.

• Developed a web application using Python Flask framework on Linux server

• Created a custom Linux kernel module for a hardware device driver

• Implemented a distributed system using Apache Kafka on Linux machines

• Optimized performance of a database server running on Linux by tuning kernel parameters

A microprocessor is a computer processor that incorporates the functions of a central processing unit on a single integrated circuit.

• Microprocessors are used in various electronic devices such as computers, smartphones, and gaming consoles.

• Register names include program counter (PC), accumulator (ACC), general-purpose registers (GPR), and memory address register (MAR).

• Registers are used to store data and instructions temporarily for processing.

• The number of registers and thei...read more

C++ is an extension of C with object-oriented programming features.

• C++ supports object-oriented programming while C does not.

• C++ has classes and templates while C does not.

• C++ has better support for exception handling than C.

• C++ has a standard library while C does not.

• C++ allows function overloading while C does not.

Arrays are contiguous blocks of memory while linked lists are made up of nodes that point to the next node.

• Arrays have fixed size while linked lists can grow dynamically.

• Insertion and deletion are faster in linked lists than in arrays.

• Arrays have better cache locality while linked lists have better memory utilization.

• Arrays are accessed using indices while linked lists are accessed using pointers.

• Examples of arrays include int[] and char[] while examples of linked lists inclu...read more

The process of converting Example.c file to Example.exe involves several steps.

• Preprocessing: includes header file inclusion, macro expansion, and conditional compilation

• Compilation: converts source code to object code

• Linking: combines object code with libraries to create executable file

• Debugging: identifying and fixing errors in code

• Optimization: improving performance of executable file

Data abstraction is the process of hiding implementation details and showing only necessary information.

• Abstraction is achieved through abstract classes and interfaces.

• It helps in reducing complexity and increasing efficiency.

• Example: abstract class Shape with abstract method draw() implemented by its subclasses like Circle and Rectangle.

I am comfortable working with multiple languages and have experience in doing so.

• I have experience working with languages such as Java, Python, C++, and JavaScript.

• I am able to quickly adapt to new languages and learn them efficiently.

• I understand the importance of proper documentation and commenting in code to ensure readability for others.

• I have worked on projects that required integration of multiple languages, such as a web application with a backend in Python and a front...read more

Let, Const, and Var are used to declare variables in JavaScript with different scoping and reassignment abilities.

• Var has function scope and can be redeclared and reassigned.

• Let has block scope and can be reassigned but not redeclared.

• Const has block scope and cannot be reassigned or redeclared.

Optimizing a React app involves reducing bundle size, using lazy loading, and optimizing rendering performance.

• Reduce bundle size by code splitting and using dynamic imports

• Use lazy loading to load components only when needed

• Optimize rendering performance by using shouldComponentUpdate and PureComponent

• Use React.memo to memoize functional components

• Avoid unnecessary re-renders by using useMemo and useCallback

• Use performance profiling tools like React DevTools and Chrome DevTo...read more

Array is a collection of similar data types. Constructor is a special method used to initialize objects. Class is a blueprint while object is an instance of a class.

• Array is used to store multiple values in a single variable.

• Constructor is called when an object of a class is created.

• Class defines the properties and methods of an object while object is an instance of a class.

• Example of array: int[] numbers = {1, 2, 3};

• Example of constructor: public class Car { public Car() { /...read more

Prelayout signal integrity is the analysis of signal quality before the layout of a printed circuit board.

• It involves simulating the behavior of signals on a PCB before the actual layout is done.

• The goal is to identify potential signal integrity issues and correct them before the layout is finalized.

• Tools such as SPICE simulators and electromagnetic field solvers are used for prelayout signal integrity analysis.

• Factors such as trace length, impedance, and crosstalk are consid...read more

SQL query to join two tables

• Use JOIN keyword to combine two tables based on a common column

• Specify the columns to be selected using SELECT keyword

• Use ON keyword to specify the common column between two tables

Recursion is a technique where a function calls itself to solve a problem. WAP for recursion is to write a program using recursion.

• Recursion is used to solve problems that can be broken down into smaller sub-problems.

• The base case is the condition where the function stops calling itself.

• The recursive case is where the function calls itself with a smaller input.

• Example: Factorial of a number can be calculated using recursion.

• Example: Fibonacci series can be generated using rec...read more

There are multiple ways to find elements on a page in Selenium, including by ID, name, class name, tag name, link text, partial link text, XPath, and CSS selector.

• By ID: driver.findElement(By.id("elementId"))

• By name: driver.findElement(By.name("elementName"))

• By class name: driver.findElement(By.className("className"))

• By tag name: driver.findElement(By.tagName("tagName"))

• By link text: driver.findElement(By.linkText("linkText"))

• By partial link text: driver.findElement(By.partia...read more

The service that needs to run to connect to other unified communication applications is the Session Initiation Protocol (SIP).

• Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, modifying, and terminating real-time sessions involving video, voice, messaging, and other communications applications.

• SIP is commonly used in Voice over IP (VoIP) systems and allows for the establishment and control of multimedia communication sessions.

• By runni...read more

Logs should be taken from the network devices involved in the call flow.

• Check logs on the caller's iPhone

• Check logs on the recipient's iPhone

• Check logs on the network devices (routers, switches) involved in the call flow

• Look for any error messages or anomalies in the logs

• Analyze the logs to identify any network issues or misconfigurations

IBIS models can be verified by comparing simulation results with actual measurements.

• Compare simulation results with actual measurements

• Use a variety of test cases to ensure accuracy

• Verify the model's compliance with IBIS standards

• Check for consistency with other models and datasheets

C is a procedural language, C++ is an object-oriented language, and Java is a class-based object-oriented language.

• C is a low-level language with limited abstraction and no built-in support for object-oriented programming.

• C++ is an extension of C with added support for object-oriented programming, templates, and exception handling.

• Java is a high-level language with automatic memory management, platform independence, and a large standard library.

• C and C++ are compiled language...read more

JVM is a virtual machine that executes Java bytecode. JDK is a development kit that includes JRE and tools for developing Java applications. JRE is a runtime environment that executes Java bytecode.

• JVM stands for Java Virtual Machine and is responsible for executing Java bytecode.

• JDK stands for Java Development Kit and includes JRE along with tools for developing Java applications.

• JRE stands for Java Runtime Environment and provides a runtime environment for executing Java by...read more

State and props are two important concepts in React. State represents the internal data of a component, while props are used to pass data from a parent component to a child component.

• State is mutable and can be changed within a component.

• Props are read-only and cannot be modified within a component.

• State is used to manage component-specific data, while props are used for inter-component communication.

• State is initialized and managed within a component, while props are passed ...read more

TCP/IP is a protocol used for communication between devices on the internet. OSI model is a conceptual framework for network communication.

• TCP/IP is a suite of protocols that governs communication between devices on the internet.

• OSI model is a conceptual framework that divides network communication into seven layers.

• TCP/IP is based on a four-layer model, which includes the application, transport, internet, and network access layers.

• The OSI model includes the physical, data li...read more

Program counter is a register that stores the memory address of the next instruction to be executed by the processor.

• Program counter is also known as instruction pointer.

• It is a part of the processor's control unit.

• The value of program counter is incremented after each instruction is executed.

• If a program counter is corrupted, the processor may execute incorrect instructions.

• Example: If the program counter is pointing to memory address 100, the next instruction to be executed...read more

Switching is the process of connecting devices in a network.

• Packet switching breaks data into packets and sends them individually through the network.

• Circuit switching establishes a dedicated communication path between two devices.

• Packet switching is more efficient and flexible than circuit switching.

• Examples of packet-switched networks include the Internet and Ethernet.

• Examples of circuit-switched networks include traditional telephone networks.

To get unique elements from a list, use set() function.

• Convert the list to a set using set() function

• Convert the set back to list using list() function

• Example: list(set(['apple', 'banana', 'apple', 'orange'])) will return ['apple', 'banana', 'orange']

Local Storage is persistent storage that remains even after the browser is closed, while Session Storage is temporary and is cleared when the browser is closed.

• Local Storage has no expiration date, while Session Storage is cleared when the session ends

• Local Storage can store larger amounts of data compared to Session Storage

• Local Storage is accessible across different browser tabs and windows, while Session Storage is limited to the current tab or window

• Local Storage can be a...read more

Disadvantages of Frame 9FA gas turbine include high maintenance costs, lower efficiency compared to newer models, and environmental concerns.

• High maintenance costs due to complex design and aging components

• Lower efficiency compared to newer gas turbine models, resulting in higher fuel consumption

• Environmental concerns such as emissions of greenhouse gases and pollutants

• Limited flexibility in terms of load following capabilities

• Noise and vibration issues during operation

Launch 100 windows and select a particular window from opened tabs

• Use a loop to launch 100 windows

• Keep track of each window's handle or identifier

• Use the handle or identifier to select the desired window

Code to sort array elements without duplicates

• Use a Set to store unique elements while iterating through the array

• Convert the Set back to an array for the final result

• Use Array.sort() method to sort the elements in the array

Single linked list operations involve adding and deleting nodes in a linear data structure.

• To add a node, create a new node and set its next pointer to the current head, then set the head to the new node.

• To delete a node, traverse the list until the node to be deleted is found, then set the previous node's next pointer to the node after the one being deleted.

• Be careful to handle edge cases such as adding to an empty list or deleting the head node.

Yes, I use console to locate elements in a web page for debugging and testing purposes.

• Yes, I use console commands like document.querySelector() or document.getElementById() to locate elements on a web page.

• Console is helpful for quickly testing and verifying element selectors before implementing them in automated tests.

• Using console to locate elements can help in identifying issues with element selection and improve test script efficiency.

Yes, I use the console to locate elements in web pages for debugging and testing purposes.

• I use the console to inspect elements and identify unique attributes like IDs, classes, or XPath.

• I can use commands like document.getElementById(), document.querySelector(), or $() to locate elements.

• I also use the console to test CSS selectors and verify if elements are being correctly identified.

Linux is preferred over Windows for servers due to its stability, security, flexibility, and cost-effectiveness.

• Linux is open-source, allowing for customization and flexibility in server configurations.

• Linux is known for its stability and reliability, making it a popular choice for servers that require constant uptime.

• Linux has a strong focus on security, with regular updates and a large community of developers actively working to address vulnerabilities.

• Linux is cost-effecti...read more

I have worked on various hardware tools including oscilloscopes, logic analyzers, multimeters, and soldering irons.

• Oscilloscopes

• Logic analyzers

• Multimeters

• Soldering irons

To delete CTL and ITL files from a phone, access the phone's settings, navigate to the security or device administration section, and delete the files.

• Access the phone's settings

• Navigate to the security or device administration section

• Locate the CTL and ITL files

• Delete the files

Promise is a callback function that returns a value in the future. Async-Await is a syntax that simplifies working with Promises.

• Promises are used to handle asynchronous operations and avoid callback hell.

• Async-Await is a syntax that allows writing asynchronous code that looks like synchronous code.

• Async-Await is built on top of Promises and uses the same underlying mechanism.

• Async-Await can only be used within an async function.

• Async-Await can handle errors using try-catch b...read more

To execute a COBOL-DB2 program using JCL code, include the necessary job control statements and specify the program name and input/output files.

• Include job control statements like JOB, EXEC, and DD statements in the JCL code.

• Specify the program name in the EXEC statement, along with any necessary parameters.

• Define input and output files using DD statements.

• If the dynamic called program is completed with the 'nodynam' option, it means that the program will not be dynamically c...read more