Array Intersection, Union, Difference

Set operations on arrays can be implemented using combinations of filter, includes, and Set objects. When dealing with large arrays, Set provides O(n) performance.

Intersection (common elements)

const arr1 = [1, 2, 3, 4];
const arr2 = [3, 4, 5, 6];

const intersection = arr1.filter((x) => arr2.includes(x));
console.log(intersection); // [3, 4]

// Using Set for efficiency
const set2 = new Set(arr2);
const intersectionSet = arr1.filter((x) => set2.has(x));
console.log(intersectionSet); // [3, 4]

Union (all unique elements from both arrays)

const union = [...new Set([...arr1, ...arr2])];
console.log(union); // [1, 2, 3, 4, 5, 6]

Difference (elements in arr1 but not in arr2)

const difference = arr1.filter((x) => !arr2.includes(x));
console.log(difference); // [1, 2]

// Using Set
const set2ForDiff = new Set(arr2);
const differenceSet = arr1.filter((x) => !set2ForDiff.has(x));
console.log(differenceSet); // [1, 2]

Symmetric Difference (elements in either, but not both)

const symDiff = [...arr1.filter((x) => !arr2.includes(x)), ...arr2.filter((x) => !arr1.includes(x))];
console.log(symDiff); // [1, 2, 5, 6]

Using Set for all operations (with duplicates removal)

// For arrays with potential duplicates, consider preserving duplicates or using Set logic.