Comparing Two Arrays in Optimized Way 0(n)

CompareArrays.js

function itemInCommon(arr1, arr2) {
    let obj = {}
    for(let i = 0; i < arr1.length; i++)
        obj[arr1[i]] = true

    for (let i = 0; i < arr1.length; i++) {
        obj[arr1[i]] = true
    }
    for (let j = 0; j < arr2.length; j++) {
        if (obj[arr2[j]]) return true
    }
    return false
}

console.log(itemInCommon(array1, array2));