javascriptintermediate10 minutes

Fix the Array Filtering Bug to Return Unique Even Numbers

A function meant to filter even numbers from an array and remove duplicates is currently returning incorrect results. Debug the code to ensure it returns only unique even numbers in ascending order.

Challenge prompt

You are given a function getUniqueEvenNumbers that takes an array of integers and is expected to return an array of unique even numbers sorted in ascending order. However, the provided code currently has bugs that prevent it from functioning correctly. Your task is to fix the bugs so that the function returns the correct output. For example, input [1, 2, 2, 3, 4, 4, 5, 6] should return [2, 4, 6].

Guidance

• Check how the function filters even numbers and removes duplicates.
• Ensure the output array only contains unique even numbers sorted in ascending order.

Hints

• Remember that Array.filter is helpful for filtering based on conditions.
• Use a Set or similar approach to remove duplicates from an array.
• Make sure sort is applied correctly to numbers (not as strings).

Starter code

function getUniqueEvenNumbers(arr) {
  // Filter even numbers
  const evens = arr.filter(num => num % 2 === 0);

  // Remove duplicates
  const uniqueEvens = evens.filter((num, index) => evens.indexOf(num) === index);

  // Sort numbers ascending (bug: sorting as strings)
  uniqueEvens.sort();

  return uniqueEvens;
}

// Example usage:
console.log(getUniqueEvenNumbers([1, 2, 2, 3, 4, 4, 5, 6]));

Expected output

[2, 4, 6]

Core concepts

array filteringremoving duplicatessorting arraysdebugging

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