SOURCE

function solution(arr1, arr2){
    let diff1 = [] // 只有arr1有
    let diff2 = [] // 只有arr2有
    for(let t of arr1){
        if(!arr2.includes(t)){
            diff1.push(t)
        }
    }

    for(let t of arr2){
        if(!arr1.includes(t)){
            diff2.push(t)
        }
    }
    //
    if(diff1.length===0 && diff2.length ===0){
        console.log("same")
    }
    if(diff1.length===0 && diff2.length !==0){
        console.log("arr1 in arr2")
    }

    if(diff1.length!==0 && diff2.length ===0){
        console.log("arr2 in arr1")
    }

    if(diff1.length!==0 && diff2.length !==0){
        console.log("arr2 different from arr1")
    }
}

solution([1,2,3], [2,3])
const a = [1,2]
const b = a
solution([1,2,3,a], [2,3,b])