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Node Js Backend Developer

Jarvis Invest

2 rounds | 5 Coding problems

Kuldeep Hada

Experienced | May 2025

Rejected

Interview preparation journey

Journey

I was consistently preparing on a regular basis by learning and implementing new skills, while also applying my knowledge through tasks and projects in my current organization. This approach helped me strengthen both my theoretical understanding and practical application.

Preparation

Topics: NodeJS , MySQL, MongoDB, Restful API's

Application process

Where: Coding Ninjas Placement Cell

Eligibility: Bachelor's or Master's degree in CS

Interview rounds

Round

Easy

Online Coding Interview

Duration

Interview date5 May 2025

Coding problem3

1. Resolving Promises in JavaScript

In JavaScript, promises are used to handle asynchronous operations. The task is to write code that creates a promise, resolves it successfully, and handles its output using .then() for success and .catch() for errors.

Problem approach

I first wrote a simple function to demonstrate the basic logic. After that, I modified the same logic by implementing Promises, showing how the function can handle asynchronous operations. While explaining, I highlighted how using Promises changes the way results are managed—by returning success or failure asynchronously instead of blocking execution.

2. ACID Properties in Database Transactions

Can you explain what ACID properties are in the context of database transactions? Walk me through ACID with an example, say a money transfer between two bank accounts.

3. Primary Key and Foreign Key

What’s the difference between a Primary Key and a Foreign Key?

Round

Medium

Online Coding Interview

Duration

Interview date6 May 2025

Coding problem2

1. Extending Array Prototype with a Custom Method

The task is to create an array of fruits and extend the Array prototype by adding a custom method addFruit. This method should allow users to add a new fruit to the existing array. By implementing this, the array gains a reusable function that can be called on any array instance to dynamically add elements.

Problem approach

Iterate over the array using a for...in loop and log the keys of the array.
Iterate again with a for...in loop and log the indices of the array elements.
Use the custom addFruit method (added to the Array.prototype) to insert a new fruit, "grape", into the array.
Finally, iterate over the array using a for...of loop to print all the fruit names in the array.

2. Find the Top 3 Best-Performing Employees by Sales Revenue

You are given two tables:

employees – contains employee details.
sales – contains the sales data for each employee, including the revenue generated.

The task is to write a query that calculates the total sales revenue for each employee by joining the two tables and then retrieves the top 3 employees who have the highest total sales revenue.

Problem approach

Using of this concepts-