Frontend Developer

What is the difference between let, var, and const in JavaScript? (Learn)

Given an array of objects, group the objects based on a specific key.
The key can be any property present in the objects and will be provided as input.

Input:
const data = [
 { name: "Alice", city: "Delhi", age: 25 },
 { name: "Bob", city: "Mumbai", age: 30 },
 { name: "Charlie", city: "Delhi", age: 22 },
 { name: "David", city: "Mumbai", age: 28 },
 { name: "Eve", city: "Pune", age: 26 }
];
const groupByKey = "city";

Expected Output:
{
 "Delhi": [
   { name: "Alice", city: "Delhi", age: 25 },
   { name: "Charlie", city: "Delhi", age: 22 }
 ],
 "Mumbai": [
   { name: "Bob", city: "Mumbai", age: 30 },
   { name: "David", city: "Mumbai", age: 28 }
 ],
 "Pune": [
   { name: "Eve", city: "Pune", age: 26 }
 ]
}

What is the difference between debouncing and throttling? (Learn)

What is useEffect, and how does the cleanup function work in useEffect? (Learn)

A few basic CSS questions, such as positioning and flexbox.

Problems based on speed, distance, and time, missing numbers, and seating arrangements were asked.

You are given a starting position for a rat which is stuck in a maze at an initial point (0, 0) (the maze can be thought of as a 2-dimensional plane). The maze would be given in the form of a square matrix of order 'N' * 'N' where the cells with value 0 represent the maze’s blocked locations while value 1 is the open/available path that the rat can take to reach its destination. The rat's destination is at ('N' - 1, 'N' - 1). Your task is to find all the possible paths that the rat can take to reach from source to destination in the maze. The possible directions that it can take to move in the maze are 'U'(up) i.e. (x, y - 1) , 'D'(down) i.e. (x, y + 1) , 'L' (left) i.e. (x - 1, y), 'R' (right) i.e. (x + 1, y).

Note:

Here, sorted paths mean that the expected output should be in alphabetical order.

For Example:

Given a square matrix of size 4*4 (i.e. here 'N' = 4):
1 0 0 0
1 1 0 0
1 1 0 0
0 1 1 1 
Expected Output:
DDRDRR DRDDRR 
i.e. Path-1: DDRDRR and Path-2: DRDDRR

The rat can reach the destination at (3, 3) from (0, 0) by two paths, i.e. DRDDRR and DDRDRR when printed in sorted order, we get DDRDRR DRDDRR.

A monkey is given ‘n’ piles of bananas, where the 'ith' pile has ‘a[i]’ bananas. An integer ‘h’ is also given, which denotes the time (in hours) in which all the bananas should be eaten.

Each hour, the monkey chooses a non-empty pile of bananas and eats ‘m’ bananas. If the pile contains less than ‘m’ bananas, then the monkey consumes all the bananas and won’t eat any more bananas in that hour.

Find the minimum number of bananas ‘m’ to eat per hour so that the monkey can eat all the bananas within ‘h’ hours.

Example:

Input: ‘n’ = 4, ‘a’ =  [3, 6, 2, 8] , ‘h’ = 7

Output: 3

Explanation: If ‘m’ = 3, then 
The time taken to empty the 1st pile is 1 hour.
The time taken to empty the 2nd pile is 2 hour.
The time taken to empty the 3rd pile is 1 hour.
The time taken to empty the 4th pile is 3 hour.
Therefore a total of 7 hours is taken. It can be shown that if the rate of eating bananas is reduced, they can’t be eaten in 7 hours.

• The interviewer asked about my projects: what I did and how I implemented them.
• Questions on the folder structure I followed.
• Why I used Redux instead of React Context for global state management.
• Whether I applied any optimization techniques in my projects.
• Questions about useCallback and useMemo in React.
• Asked me to implement useCallback in my existing project.
• Rendering-related questions:
• If there is a parent component with a child component inside it, will the child re-render when the parent state updates?
• If yes, how can we prevent the child from re-rendering if it does not use any state or props from the parent?

function update(obj) {
 obj.x = 2;
 obj = { x: 3 };
 obj.y = 4;
}
const myObj = { x: 1 };
update(myObj);
console.log(myObj);

What is the difference between a deep copy and a shallow copy? (Learn)

This round was with the CEO. He asked general questions about my tech stack, my work experience, and the career gap in my resume. He was not satisfied with the gap and ultimately rejected me.