My Interview Experience for Zepto SDE-2 Frontend Role

Overview

This case study outlines a candidate's interview experience for the Software Development Engineer 2 (SDE-2) Frontend position at Zepto. The process was designed to evaluate the candidate's technical skills and problem-solving capabilities. This document provides a structured breakdown of the interview rounds and key takeaways.

Interview Rounds

The interview process consisted of two technical rounds.

Round 1: Technical Interview

This round began with an introduction and a discussion of the candidate's resume, focusing on previous projects and technologies. The interviewer probed the specifics of the candidate's contributions.

Question 1: Infinite Currying

The candidate was asked to implement infinite currying in JavaScript. The solution required a strong understanding of closures, function length properties, and argument management.

function curry(func) {
  let args = func.length;
  const totalArgs = [];
  return function inner(a) {
    args--;
    console.log(args, totalArgs);
    if (args === 0) {
      return func(...totalArgs);
    }
    totalArgs.push(a);
    return inner;
  };
}

function sum(a, b, c) {
  return a + b + c;
}
sum.length = 3;
let curriedSum = curry(sum);
console.log(curriedSum(2)(3)(4)); // Output: 9

The curry function transforms a given function into its curried equivalent. It leverages func.length to determine the expected number of arguments. The inner function recursively collects arguments until the required count is met, then invokes the original function with the accumulated arguments using the spread operator.

Question 2: Countdown Timer

The candidate was tasked with creating a countdown timer in JavaScript with the following features:

• Start/Stop functionality
• Pause functionality
• Reset functionality
• Time display in HH:MM:SS format

This question assessed the candidate's ability to manage time-based operations, manipulate the DOM, and handle events. The candidate implemented the timer using setInterval, maintained state to track the timer's status, and ensured clear time formatting logic.

Round 2: React-Focused Technical Interview

This round concentrated on React.js concepts and practical implementation.

Question 1: Stepper Component

The candidate was required to build a Stepper component in React, allowing users to navigate a multi-step form. The component needed to persist form data across different steps. An example stepper was provided.

Question 2: Traffic Light Simulation

The candidate was challenged to render a sequence of three traffic lights (red, yellow, green) in an infinite loop with the following timings:

• Red light: 3000ms
• Yellow light: 1000ms
• Green light: 300ms

The implemented solution used useState to manage the active light and setInterval for the timing logic. The interviewer assessed the candidate's ability to handle asynchronous updates and state management efficiently.

Key Takeaways

• JavaScript Fundamentals: A strong understanding of JavaScript fundamentals, including closures, function properties, and asynchronous operations, is crucial.
• React Proficiency: Hands-on experience building dynamic components like steppers and timers is essential to demonstrate comfort with React's state management and lifecycle.
• Unforeseen Circumstances: External factors, such as role freezes, can impact the final outcome despite strong performance during the interview process.

Candidates preparing for similar roles should focus on strengthening their JavaScript fundamentals, mastering React hooks, and practicing problem-solving patterns. Clear communication of thought processes is also highly recommended during the interview.