SOURCE

function calcDate(preDate, issueDate, issueType) { // FIXME: 计算时间 
    // issueType(0 日, 1 周, 2 月, 3 季, 4 年)
  	debugger;
    let time = new Date(preDate).getTime();
    let day2ms = 1000 * 60 * 60 * 24;
    switch (issueType) {
      case '0':
        time += issueDate * day2ms;
        break;
      case '1':
        time += issueDate * day2ms * 7;
        break;
      case '2':
        time += issueDate * day2ms * 30;
        break;
      case '3':
        time += issueDate * day2ms * 30 * 3;
        break;
      case '4':
        time += issueDate * day2ms * 30 * 365;
        break;
    }
  	console.log('time',time)
    let ms2date = new Date(time);
    console.log('ms2date',ms2date);
  }

calcDate('2019-04-01',10,0);