My Apple Frontend Interview Experience | Frontend Engineer | Hyderabad

Overview

The candidate interviewed for a Frontend Engineer position at Apple in Hyderabad. The process began with a referral and progressed to a single round of online screening. This assessment evaluated the candidate's skills in problem-solving, JavaScript fundamentals, and React expertise. This document details the questions presented and the candidate's approaches to solving them.

Interview Rounds

Round 1: Online Screening (Platform Assessment)

• Role: Frontend Engineer
• Location: Hyderabad (Remote)
• Duration: 60 minutes
• Format: 10 questions (coding and theoretical)

1. Problem Solving: Fetch Keys from Nested Object / Array

The candidate was required to implement a function to extract keys pointing to primitive values from a nested object or array. The expected output was a flattened array of key paths.

Example Inputs/Outputs:

Input:

{ a: { b: {c:1}, d:2 }, e: 3 }

Output:

["a.b.c", "a.d", "e"]

Input:

[1, {a:2, b: [3,4]}, 5]

Output:

["0", "1.a", "1.b.0", "1.b.1", "2"]

Solution:

/**
 * Recursively fetches all the paths (keys) to primitive 
    values from a nested object or array.
 * 
 * @param {Object|Array} input - The input object or array to traverse.
 * @returns {Array} - An array of strings, 
    each representing the path to a primitive value.
 */
function fetchKeys(input) {
  const result = [];

  /**
   * Recursive helper function to traverse the input object/array.
   * 
   * @param {*} value - The current value being traversed.
   * @param {string} path - The current path constructed so far.
   */
  function traverse(value, path) {
    // Check if the current value is a primitive 
    // (string, number, boolean, null, etc.)
    const isPrimitive = (val) =>
      val === null || typeof val !== 'object';

    // If it's a primitive, add the path to result and stop recursion
    if (isPrimitive(value)) {
      result.push(path);
      return;
    }

    // If the value is an array, iterate over each element
    if (Array.isArray(value)) {
      value.forEach((item, index) => {
        // Construct the new path with the index
        const newPath = path ? `${path}.${index}` : `${index}`;
        traverse(item, newPath); // Recursively traverse each item
      });
    } else {
      // If it's an object, iterate over its keys
      for (const key in value) {
        if (value.hasOwnProperty(key)) {
          // Construct the new path with the key
          const newPath = path ? `${path}.${key}` : key;
          traverse(value[key], newPath); // Recursively traverse the value
        }
      }
    }
  }

  // Start traversing from the root of the input
  traverse(input, '');

  // Return the list of all paths to primitive values
  return result;
}