Walmart Interview Questions, Process, and Tips

Q1. React Coding to implement Stop watch with Start, Stop, Resume, Pause
Ans. 
Implement a React stopwatch with start, stop, resume, and pause functionalities.
• Use state to track the elapsed time

• Create functions for start, stop, resume, and pause actions

• Use setInterval for updating the timer every second

• Display the timer in the UI
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Q2. Theoretical Questions on React like Code splitting, Virtual DOM, useCallback etc.
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Q3. How does memory leak happen in Javascript
Ans. 
Memory leaks in JavaScript happen when unused objects are not properly released from memory.
• Memory leaks can occur when variables are not properly dereferenced, preventing garbage collection.

• Closures can also lead to memory leaks if they hold references to large objects.

• Event listeners can cause memory leaks if not removed properly after use.

• Using setInterval without clearing it can lead to memory leaks.

• Circular refere
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Q4. Error Handling component in React
Ans. 
Error handling in React involves creating a component to display error messages and handling errors gracefully.
• Create an ErrorBoundary component to catch errors in child components.

• Use try-catch blocks in async functions to handle errors.

• Display error messages to the user using state or props.

• Use error boundaries to prevent the entire UI from crashing due to a single error.
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Q5. Currying related problem. Implement sum(1)(2)(3)()
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Coding test in Karat platform - 1 hr duration

Q1. Coding round with Walmart SDE - asked to build a search functionality
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Q1. Coding round - Javascript based
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Q1. Coding round - asked to find a bug in a code and make it run
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Q1. Managerial round - basic questions about previous projects.
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Q1. What are the common issues faced while deploying a service to AWS?
Ans. 
Common issues faced while deploying a service to AWS
• Configuration errors leading to service downtime

• Security misconfigurations exposing sensitive data

• Performance issues due to improper resource allocation

• Network connectivity problems affecting service availability

• Lack of monitoring and logging causing difficulties in troubleshooting

• Incompatibility issues with other AWS services or third-party integrations
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Q2. Difference between @Mock and @InjectMock
Ans. 
Difference between @Mock and @InjectMock annotations in Java testing
• Use @Mock to create a mock object of a class or interface

• Use @InjectMock to inject the mock object into the class being tested

• Example: @Mock UserService userService; @InjectMock UserController userController;

• Example: Mockito.when(userService.getUserById(1)).thenReturn(new User());
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Q3. What is integration testing?
Ans. 
Integration testing is testing the interaction between different components or systems to ensure they work together correctly.
• Integration testing verifies that different modules or services work together as expected.

• It focuses on testing the interfaces and communication between components.

• Examples include testing API endpoints, database interactions, and third-party integrations.
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Q1. SQL self join related question
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Q2. Working of spark in detail
Ans. 
Spark is a distributed computing framework that processes big data in memory and is known for its speed and ease of use.
• Spark is an open-source, distributed computing system that provides an interface for programming entire clusters with implicit data parallelism and fault tolerance.

• It can run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk.

• Spark provides high-level APIs in Java, Scala...read more
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Q1. DAG implementation in detail
Ans. 
DAG implementation involves defining tasks and their dependencies in a directed acyclic graph.
• DAG is a graph where nodes represent tasks and edges represent dependencies between tasks.

• Tasks can only be executed once all their dependencies have been completed.

• Common tools for DAG implementation include Apache Airflow and Luigi.

• Example: Task A must be completed before Task B can start, forming a dependency between them.
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Q2. Explain salting in detail
Ans. 
Salting is a technique used in cryptography to add random data to passwords before hashing to prevent rainbow table attacks.
• Salting involves adding a random string of characters to a password before hashing it

• The salt value is unique for each password and is stored alongside the hashed password

• Salting prevents attackers from easily cracking passwords using precomputed rainbow tables

• Example: If a password is 'password12...read more
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