JS Array Data Transformation

Requirements

Given a list of developer profiles containing name, active status, age, and skills, write a JavaScript function that filters out inactive developers, averages the ages of active developers, and returns a sorted list of all active developer skills without duplicates.

Expected Output

A single utility function returning the aggregated telemetry: { activeDevs: string[], averageAge: number, uniqueSkills: string[] }.

Hints & Tips

1Use `.filter()` to select active developers.
2Use `.reduce()` to accumulate total ages.
3Use a ES6 `Set` to collect and deduplicate skills arrays, then sort the output.

Senior Code Review Checklist

0 / 4 Checked

Common Architectural Mistakes

1Mutating original object states instead of returning new copies.
2Forgetting to handle empty arrays, resulting in NaN division outputs.
3Using nested loops (O(N^2)) instead of mapping arrays into Set buffers.

Developer Solution

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Architectural Explanation

This function filters the arrays, computes divisions safely, extracts skills via Set, and chains conversions immutably without altering reference structures.

Code Snippet

javascript

export function transformDevelopers(devs) {
  const activeDevs = devs.filter(d => d.active);
  if (activeDevs.length === 0) {
    return { activeNames: [], averageAge: 0, uniqueSkills: [] };
  }
  
  const totalAge = activeDevs.reduce((sum, d) => sum + d.age, 0);
  const averageAge = totalAge / activeDevs.length;
  
  const skillsSet = new Set();
  activeDevs.forEach(d => {
    d.skills.forEach(skill => skillsSet.add(skill));
  });
  
  const uniqueSkills = Array.from(skillsSet).sort();
  
  return {
    activeNames: activeDevs.map(d => d.name),
    averageAge,
    uniqueSkills
  };
}

Explain in Interview

How to pitch this solution during technical interviews

I process array transformations by chaining pure immutable routines. I aggregate values like average age using reduce, and isolate arrays of lists into a unique, sorted array by leveraging ES6 Set collections.

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Requirements

Expected Output

A single utility function returning the aggregated telemetry: { activeDevs: string[], averageAge: number, uniqueSkills: string[] }.

export function transformDevelopers(devs) { const activeDevs = devs.filter(d => d.active); if (activeDevs.length === 0) { return { activeNames: [], averageAge: 0, uniqueSkills: [] }; } const totalAge = activeDevs.reduce((sum, d) => sum + d.age, 0); const averageAge = totalAge / activeDevs.length; const skillsSet = new Set(); activeDevs.forEach(d => { d.skills.forEach(skill => skillsSet.add(skill)); }); const uniqueSkills = Array.from(skillsSet).sort(); return { activeNames: activeDevs.map(d => d.name), averageAge, uniqueSkills }; }