时间增加和转换问题,谢谢解答

Question

在原有的时间基础上增加半个小时，时间类型为字符串
增加半小时，最终要的结果是字符串形式

const time = ‘8:00’
//想要的结果是'8:30'

const timeTwo = '8:30'
//想要的结果是‘9:00’

const timeThree = '14:00'
//想要的结果是‘14:30’

Answer 1

new Date(2020, 1, 1, time.split(':')[0], Number(time.split(':')[1]) + 30).toTimeString().slice(0, 5)

Answer 2

var str2minute = (str) =>{
  str = str.split(":");
 return str[0]*60 + str[1]*1
};
var minute2str = (minute) => {
  minute = minute % (24 * 60);
  var hour = Math.floor(minute/60);
  minute = minute % 60;
  return hour + 30;
};
minute2str(str2minute("12:30") + 30);