My Frontend Interview Experience at Blinkit: A Smooth Yet Challenging Ride

Overview

This document details a candidate's interview experience for a Frontend Developer position at Blinkit. The process involved a resume review, technical assessments, and behavioral questions, providing a comprehensive evaluation of the candidate's skills and suitability for the role.

Interview Rounds

Round 1: Technical Interview

The initial interview, conducted by an SDE-2 at Blinkit, commenced with a discussion of the candidate's resume and previous projects at CLEAR, PerkPass, and other ventures. The technical assessment comprised the following challenges:

JavaScript Nested Object Transformation

• Problem: The candidate was tasked with flattening a deeply nested JavaScript object into a flat structure.

  const input = {
    user: {
      name: "John",
      address: {
        city: "New York",
        zip: "10001"
      }
    }
  };
  
  // Expected Output:
  // {
  //   "user.name": "John",
  //   "user.address.city": "New York",
  //   "user.address.zip": "10001"
  // }
  

• Solution: The candidate employed a recursive approach using forEach to iterate through the object's keys and construct the flattened structure.

  function flattenObject(obj, parent = '', result = {}) {
    Object.keys(obj).forEach(key => {
      const propName = parent ? `${parent}.${key}` : key;
      if (typeof obj[key] === 'object' && obj[key] !== null) {
        flattenObject(obj[key], propName, result);
      } else {
        result[propName] = obj[key];
      }
    });
    return result;
  }
  
  console.log(flattenObject(input));
  

• Discussion: The interviewer inquired about the choice of forEach over map. The candidate clarified that forEach is more appropriate for side effects (modifying an external object), whereas map is intended for creating new arrays.

DSA Challenge: Next Permutation

• Problem: Given an array of integers, find the next lexicographical permutation. If no such permutation exists, rearrange the array to its lowest possible order.

• Sample Input: [1, 2, 3]

• Expected Output: [1, 3, 2]

• Solution:

  function nextPermutation(nums) {
    let i = nums.length - 2;
    while (i >= 0 && nums[i] >= nums[i + 1]) {
      i--;
    }
    if (i >= 0) {
      let j = nums.length - 1;
      while (nums[j] <= nums[i]) {
        j--;
      }
      [nums[i], nums[j]] = [nums[j], nums[i]];
    }
    reverse(nums, i + 1);
  }
  
  function reverse(nums, start) {
    let end = nums.length - 1;
    while (start < end) {
      [nums[start], nums[end]] = [nums[end], nums[start]];
      start++;
      end--;
    }
  }
  
  let nums = [1, 2, 3];
  nextPermutation(nums);
  console.log(nums);
  

Object Destructuring Challenge

• Problem: Destructure a deeply nested object and extract specific values.

• Sample Input:

  const data = {
    user: {
      profile: {
        name: "Alice",
        details: {
          age: 28,
          city: "San Francisco"
        }
      }
    }
  };
  

• Solution:

  const {
    user: {
      profile: {
        name,
        details: { age, city }
      }
    }
  } = data;
  
  console.log(name); // Alice
  console.log(age); // 28
  console.log(city); // San Francisco
  

Candidate's Questions

At the conclusion of the interview, the candidate inquired about Blinkit's work culture, common challenges faced by developers, and the typical work week structure.

Key Takeaways

• A strong understanding of JavaScript fundamentals, including array methods and object manipulation, is crucial.
• Familiarity with data structures and algorithms (DSA) is essential for problem-solving.
• Proficiency in ES6 features, such as object destructuring, is expected.
• Clear communication and the ability to explain one's approach are vital.
• Preparation and a calm demeanor are key to a successful interview experience.