symmetric difference

diff.js

const first = ["A", "B", "C"]
const second = ["A", "B"]

// 1) long way
const firstArrayDiff = first.filter((f) => {
  return second.includes(f) === false
})

const secondArrayDiff = second.filter((s) => {
  return first.includes(s) === false
})

if (firstArrayDiff.length || secondArrayDiff.length) {
  // something different
  console.log("long diff");
}


// 2) short way
const totalDiff = [...first.filter(f => !second.includes(f)), ...second.filter(s => !first.includes(s))]

if (totalDiff.length) {
  // something different
  console.log("short diff");
}