Quokka Labs Software Engineer Interview Questions and Answers

Q1. Rate yourself in js, node js, react, MongoDB (separately)
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Q2. Typeof null, typeof undefined, typeof {}, typeof NaN
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Q3. What changes came in es6
Ans. 
ES6 introduced several new features and improvements to JavaScript, making it more powerful and efficient.
• Arrow functions for more concise syntax

• Let and const for block-scoped variables

• Classes for easier object-oriented programming

• Template literals for easier string interpolation

• Default parameters and rest parameters for function arguments

• Destructuring assignment for easier data extraction

• Promises for asynchronous prog
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Q4. This keyword, closures, hoisting
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Q5. Are let and cont variables hoisted?
Ans. 
Yes, let and const variables are hoisted but not initialized.
• let and const variables are hoisted to the top of their block scope, but they are not initialized until the actual line of code is executed.

• This means that you cannot access a let or const variable before it is declared in the code.

• For example, trying to access a let variable before it is declared will result in a ReferenceError.
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Q6. What is global context
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Global context refers to the overall environment or setting in which something exists or operates.
• Global context encompasses all variables, functions, and objects that are accessible throughout an entire program.

• It can be thought of as the 'big picture' view of a program's execution.

• In web development, global context includes the window object in JavaScript.
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Q7. What is temporal deadzone
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Temporal dead zone is a period during the variable creation process where accessing the variable results in a ReferenceError.
• Occurs when trying to access a variable before it has been declared with let or const

• Happens due to the variable being in the temporal dead zone until it is declared

• Example: accessing a variable before its declaration will result in a ReferenceError
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Q8. What is modules? types of modules in nodejs
Ans. 
Modules in Node.js are reusable blocks of code that encapsulate related functionality.
• Modules in Node.js can be built-in modules like fs (file system) or third-party modules like express.

• Modules help in organizing code into separate files for better maintainability and reusability.

• Modules can be imported using the require() function in Node.js.
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Q9. Index in mongodb, why we need index, is index good or bad?
Ans. 
Indexes in MongoDB improve query performance by allowing the database to quickly locate and retrieve specific documents.
• Indexes help to speed up query performance by allowing the database to quickly locate specific documents based on the indexed fields.

• Without indexes, MongoDB would have to perform a collection scan, which can be slow and resource-intensive.

• Indexes can be created on single fields or compound fields to ...read more
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Q10. What are hooks , use of useRef
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Hooks are a feature in React that allow you to use state and other React features in functional components. useRef is a hook that allows you to create a mutable object that persists for the lifetime of the component.
• Hooks are used to add state and lifecycle methods to functional components in React

• useRef is used to create a mutable reference that persists between renders

• useRef can be used to access DOM elements directl
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Q11. Fs module, http module, worker thread?
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Q12. Why we use mongoose not mongodb driver?
Ans. 
Mongoose is an Object Data Modeling (ODM) library for MongoDB that provides a higher level of abstraction and simplifies interactions with the database.
• Mongoose provides schema validation which helps maintain data integrity.

• Mongoose simplifies querying and data manipulation with built-in functions.

• Mongoose supports middleware functions for pre and post processing of data operations.
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Aptitude questions were easy and basics

Q1. They asked about projects, SQL basics, oops concepts and about java concepts
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Q2. It was an easy and average interview
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Q1. Hands on coding experience is must.
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Q2. Interviewers are itself not worthy of interviewing, some scrum master with below par knowledge interviewed me.
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There will be 3 coding questions. They are of medium and hard level.

Q1. Sort array consisting 0's 1's and 2's without inbuilt functions
Ans. 
Sort an array of 0's, 1's, and 2's without using inbuilt functions.
• Use three pointers to keep track of the last index of 0's, 1's, and 2's

• Iterate through the array and swap elements based on their value

• Continue until all elements are sorted
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Q1. Os cn related questions
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Q1. Java questions and general hr questions
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There are three sections: -
1. Quants
2. English
3. Reasoning
All sections are accessible medium but you have maintained the speed and accuracy.
after that coding snippet are in java/python.

Code snippets are there in coding sections.

4 Coding Questions Were Given.
Check Palindrome String
Longest Increasing Subsequence
Group Anagrams
Add Two Numbers(Linked List)

Questions were picked from leetcode but the restriction of not using any inbuild function made them difficult to solve in the given time frame.

Q1. Basic Java Technical Questions
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Q2. Throws Vs Throw
Ans. 
Throws is used for checked exceptions in Java, while throw is used to explicitly throw an exception.
• Throws is used in method signature to declare that the method may throw a checked exception.

• Throw is used to actually throw an exception in the code.

• Example: public void method() throws IOException { //code }

• Example: throw new IOException();
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Q3. Method Overriding Basics and Output-Based Questions
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Q4. Springboot annotations
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Q5. Inheritance and Concept of Abstract Classes and Interfaces
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Inheritance allows a class to inherit properties and behaviors from another class. Abstract classes cannot be instantiated and can have abstract methods. Interfaces define a contract for classes to implement.
• Inheritance allows a class to inherit properties and behaviors from another class

• Abstract classes cannot be instantiated and can have abstract methods

• Interfaces define a contract for classes to implement
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