function commonSubString(arr1, arr2) { for (const [i, value] of arr1.entries()) { let isCommon = checkSubString(arr1[i], arr2[i]) console.log(isCommon) } } function checkSubString(s1, s2) { let shortStr; let longStr; if (s1.length < s2.length) { shortStr = s1; longStr = s2; } else { shortStr = s2; longStr = s1; } for (let i = 0; i < shortStr.length; i++) { if (longStr.indexOf(shortStr[i]) !== -1) { return "YES" } } return "NO" } let a = ["ab", "qw"] let b = ["ad", "sdlfjgsldfjaafhjklashflaksdflaskdfaskdhfaskasdf"] console.log(commonSubString(a, b))