Interlace India Trainee Software Test 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
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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?
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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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Q1. Difference between function and method
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Q2. A program related to strings
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Q3. A program related to prime numbers
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Q1. What is git, how GitHub work without git
Ans. 
Git is a version control system used for tracking changes in code. GitHub is a platform for hosting code repositories and collaborating with others.
• Git is a distributed version control system that allows multiple developers to work on the same codebase without conflicts.

• GitHub is a web-based platform that provides hosting for Git repositories, along with additional features like issue tracking, pull requests, and proje...read more
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Q2. What is salting, hashing, rainbow table
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Salting, hashing, and rainbow tables are techniques used in cryptography to secure passwords.
• Salting involves adding a random string of characters to a password before hashing to prevent attacks like rainbow tables.

• Hashing is the process of converting a password into a fixed-length string of characters using a cryptographic hash function.

• Rainbow tables are precomputed tables used to crack hashed passwords by matching a
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Q1. What is single page application
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Single page application is a web application that loads a single HTML page and dynamically updates the content as the user interacts with the app.
• SPA uses AJAX and HTML5 to create fluid and responsive user experience.

• It eliminates the need for page reloading during use, making it faster and more efficient.

• Examples include Gmail, Facebook, and Google Maps.
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Q2. What is state management
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State management is the process of managing the state of an application, including data flow, user interface updates, and user interactions.
• State management involves storing and updating the state of an application to ensure data consistency.

• It helps in managing user interface updates based on changes in the application state.

• State management is crucial for handling user interactions and maintaining a seamless user exp...read more
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Q1. Basic flutter coding questions
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Q1. What is jdk, string related questions, basic java oops questions?
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The company came on campus, and it was the very first round in which it was not a group discussion, more it was like an individual interview within a group of 10 people of my college, the interviewer asked question on Polymorphism, Inheritance and difference between class and structure and told everyone to not to speak same answer as the groupmate it was all live and was proctored.
I was the only Person out of sixty one students who were shortlisted for face to face interview in Noida add the company's office itself I reached there add two in the noon There was no receptionist I waited for like 57 minutes on the sofa I knocked the gate nobody answered it again knocked the gate there was a developer standing over I asked him to come out and I had a word with him and what the statement he gave me I was in shock he asked me why are you here and for what purpose you are here I was like bro is this for real I told him I had an interview scheduled and I came all the way from a particular place which is 280 kilometers one side from their office and I started 4 in the morning.

They gave me a coding question paper in which there were two questions number one was reverse a string and input sample input was Helo and we have to reverse that and the next question was of matrix in which the question was there is a matrix of M Cross N Rows you have to spiral traverse it in clockwise direction and output the elements in one day array form this was the question so I had to solve this I solved both the questions but the 1st 1 was absolutely easy I cleared it very easily and the second question it was little bit tricky and it was of medium level so I attempted it and 15 to 20% I made some logic and gave the paper to the HR that I am done with the paper you can give it to the concerned developer and After my paper got checked the developer came It was that developer only Whom I have mentioned in the very first paras he was from Bihar he came to me he told me Explain both the programs I explained him the first one very easily and I explained him the 2nd one program's approach as welI I did knew that it was not absolutely right but yeah I told him the approach that I used so he told me to explain me the very first program which was reversing of string without using the logic which I used the logic that I used was of slicing he said me that he told me that I don't have to use this logic And neither I have to use a direct function he told me you have to solve this program by a logic in which you don't have to define a new variable I was like I asked him questions back and forth for 5 to 7 minutes we had a discussion and I gave him the code in python he said no so I gave him the code in C++, in C++ when I used the loop so I have to initialize i that means I have initialized a new variable I gave him the paper I made my hands up I was like no sir I'm not able to do it if you can do it would be very appreciable so he took the pen and wrote the code and the funniest thing I found about that when he wrote the entire code he defined 3 new variables and I was like you told me not to do that and you're doing it by yourself and I asked the interviewer very politely sir you have defined 3 new variables so he told me no no no the question that I wanted to ask you that there should be low space complexity I was like what the heck bro he didn't ask me this question and to defend his answer he told me that we can erase these things these 3 things I was like if I would have done that you weren't allowing me to erase that and if you did then you can erase that bravo!!! well done this entire process was completed in less than 5 minutes then the HR came she told me we will intimate me the result through my WhatsApp but I asked her again she told me we will intimate you through WhatsApp and when I came out of the office I knew it because they didn't have my WhatsApp number I knew it so moral of the story is I wasted my 20 hours of single day because I traveled back to the same place from where I started I lost my 20 hours just for the sake of 5 minute interview and how on Earth you can judge a software developer trainee interviewe in less than 5 minutes.

Q1. So you have prior experience with Javascript ?
Ans. 
Yes, I have prior experience with Javascript.
• I have worked on various projects using Javascript.

• I am familiar with popular Javascript libraries and frameworks like React and Node.js.

• I have experience in writing clean and efficient Javascript code.

• I have used Javascript for both front-end and back-end development.
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In the previous round, they give you a link to freecodecamp course - basic javascript.
In this round (Coding) every single question is asked from the exact same course, as is.

Q1. The HR discusses salary and commutation and other things
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