javascript - Javascript:输入日期-当前日期函数接近但不太正确？

我正在尝试编写一个函数，该函数在给定过去的日期时将以滴加余数的方式计算年，月和日。与“2年1个月3天”一样，不是所有3种格式的总时间(2年= 24个月= 730天)。

码:

    //Function to tell years/months/days since birthday to today
var ageID = function(date){
    var nowDate = new Date();

  //current date
    var nowYear = nowDate.getFullYear();
    var nowMonth = nowDate.getMonth();
    var nowDay =  nowDate.getDay();

  //input birthday
    var year = date[0];
    var month = date[1];
    var day = date[2];

  var longMonth = [1, 3, 5, 7, 8, 10, 12];
    var shortMonth = [4, 6, 9, 11];
    var febMonth = [2];
  var specfMonth = 0;

  //finding month that corresponds to 28, 30, or 31 days in length
  for (i = 0; i < longMonth.length; i++){
    if (longMonth[i] === month){
        specfMonth = 31;
    }
  }
  for (i = 0; i < shortMonth.length; i++){
        if (shortMonth[i] === month){
            specfMonth = 30;
    }
    }
    for (i = 0; i < febMonth.length; i++){
        if (febMonth[i] === month){
            specfMonth = 28;
      }
    }

  //Reduced input and current date
  var redYear = nowYear - year - 1;
  var redMonth = 0;
  var redDay = 0;




  //The following 2 if/else are to produce positive output instead of neg dates.
  if (nowMonth < month){
    redMonth = month - nowMonth;
  }else{
    redMonth = nowMonth - month;
  }

  if (nowDay < day){
    redDay = day - nowDay;
  }else{
    redDay= nowDay - day;
  }

    var adjMonth = 12 - redMonth;
    var adjDay = specfMonth - redDay;

  if (redYear < 1){
      return adjMonth + " months, " + adjDay + " days ago.";
    }else{
      return redYear + " years, " + adjMonth + " months, " + adjDay + " days ago.";
    }
};

console.log(ageID([2001, 9, 11]));

输出:13 years, 10 months, 20 days ago.
但是，准确的输出将是:13 years, 10 months, 30 days ago.

最佳答案

您的问题是:var nowDay = nowDate.getDay();
您应该使用:nowDate = nowDate.getDate();代替。
getDay()返回一周中的天数。
星期一是“1”，星期二是“2”，依此类推。