function trans(s, n) { let arr = s.split(/\s/); let res = []; let temp; while (arr.length) { temp = arr.pop() temp = temp.split('') temp.forEach((word,i) => { if (/[a-z]/.test(word)) { temp[i] = word.toUpperCase() }else if (/[A-Z]/.test(word)) { temp[i] = word.toLowerCase() } }); res.push(temp); ...