Finding the Union of Arrays in JavaScript

The union of arrays represents all unique elements present in either of the input arrays. This operation is fundamental in set theory and has practical applications in data processing, such as combining data from multiple sources while avoiding duplicates. Your task is to write a JavaScript function that efficiently calculates the union of two arrays.

Problem Description

You are required to implement a function called union that takes two arrays as input and returns a new array containing the union of the two input arrays. The resulting array should contain only unique elements, and the order of elements in the output array does not matter. The function should handle various input scenarios, including empty arrays and arrays with duplicate elements.

Key Requirements:

• The function must accept two arrays as input.
• The function must return a new array containing the union of the input arrays.
• The resulting array must contain only unique elements.
• The function should be efficient in terms of time complexity.
• The function should handle edge cases gracefully.

Expected Behavior:

The function should iterate through both input arrays and add elements to the result array only if they are not already present. Using a Set data structure is a recommended approach for efficient uniqueness checking.

Edge Cases to Consider:

• Empty input arrays: If either or both input arrays are empty, the function should return the other array (or an empty array if both are empty).
• Arrays with duplicate elements: The function should ensure that the resulting array contains only unique elements, even if the input arrays contain duplicates.
• Arrays with different data types: The function should handle arrays containing different data types (e.g., numbers, strings, booleans) correctly. Consider how you want to handle mixed types.
• Arrays with null and undefined values: Decide how you want to handle these values. Should they be included in the union?

Examples

Example 1:

Input: [1, 2, 3], [3, 4, 5]
Output: [1, 2, 3, 4, 5]
Explanation: The union of [1, 2, 3] and [3, 4, 5] is [1, 2, 3, 4, 5]. The duplicate '3' is removed.

Example 2:

Input: [1, 2, 2, 3], [3, 4, 4, 5]
Output: [1, 2, 3, 4, 5]
Explanation: The union of [1, 2, 2, 3] and [3, 4, 4, 5] is [1, 2, 3, 4, 5]. Duplicate elements are removed from both input arrays before creating the union.

Example 3:

Input: [], [1, 2, 3]
Output: [1, 2, 3]
Explanation: The union of an empty array and [1, 2, 3] is [1, 2, 3].

Example 4:

Input: [1, "hello", true], [true, 2, "world"]
Output: [1, "hello", true, 2, "world"]
Explanation: The union of arrays with mixed data types is handled correctly.

Constraints

• The input arrays can contain any data type.
• The length of the input arrays can vary from 0 to 1000.
• The function should have a time complexity of O(n + m), where n and m are the lengths of the input arrays. Using a Set is highly recommended to achieve this.
• The function should not modify the original input arrays.

Notes

Consider using a Set data structure in JavaScript to efficiently track unique elements. Sets provide constant-time complexity for checking the existence of an element. Think about how to handle null and undefined values consistently. The order of elements in the output array is not important, so you can use any suitable data structure to build the union.