isEqualArray.js

function isEqualArray(a, b) {
  if (a === b) return true
  if (a == null || b == null) return a !== a && b !== b
  if (a.length !== b.length) return false

  const aHasB = a.every(aValue => b.includes(aValue))
  const bHasA = b.every(bValue => a.includes(bValue))
  return aHasB && bHasA
}

isEqualArray([1], undefined) // false
isEqualArray(undefined, undefined) // true
isEqualArray(null, undefined) // false
isEqualArray(null, [1]) // false
isEqualArray(undefined, [1]) // false
isEqualArray([1], [1]) // true
isEqualArray([1], [1, 2]) // false
isEqualArray([1, 2], [1]) // false
isEqualArray([1, 2], [1, undefined]) // false
isEqualArray([1, undefined], [1, undefined]) // true