Unicode编码:小写字母a-z的code为97 - 122，大写字母A-Z的code为65 - 90

统计大写字母的个数

var str ="abcABCadDGSDVBSDVDSVdavver"var count=0for(let i = 0;i<str.length;i++){var char = str[i].charCodeAt()if(char>=65&&char<=90){count++}}console.log(count+'个')//大写字母共15个

小写字母的个数

var str ="abcABCadDGSDVBSDVDSVdavver"var count=0for(let i = 0;i<str.length;i++){var char = str[i].charCodeAt()if(char>=97&&char<=122){count++}}console.log(count+'个')//小写字母共11个