Remove Duplicates from an Array

📌 Definition:

📖 Detailed Explanation:

The idiomatic ES6 way uses a Set, which stores unique values: [...new Set(arr)]. For arrays of objects (deduping by a key) you use a Map or a seen-set of keys.

💻 Solutions:

• JavaScript

const unique = (arr) => [...new Set(arr)];

// Dedupe objects by a key:
function uniqueBy(arr, key) {
  const seen = new Set();
  return arr.filter((o) => {
    if (seen.has(o[key])) return false;
    seen.add(o[key]);
    return true;
  });
}

🔑 Key Points:

• [...new Set(arr)] dedupes primitives in O(n)
• Set uses SameValueZero equality (NaN dedupes correctly)
• Objects need dedupe-by-key (Set of references won't help)
• Preserves insertion order

🌍 Real-World Example: