javascript日期减法

Question

我正在寻找一种方法在两个javascript Date对象之间进行适当的减法并获得日期增量.

这是我的方法,但它在今天的日期作为输入失败:

<script type="text/javascript">
function getDayDelta(incomingYear,incomingMonth,incomingDay){
var incomingDate = new Date(incomingYear,incomingMonth,incomingDay);
var today = new Date();

var delta = incomingDate - today;
var resultDate = new Date(delta);
return resultDate.getDate();
}
//works for the future dates:
alert(getDayDelta(2009,9,10));
alert(getDayDelta(2009,8,19));

//fails for the today as input, as expected 0 delta,instead gives 31:
alert(getDayDelta(2009,8,18));
</script>

对此更好的方法是什么？

Answer 1

Date构造函数中的月份数基于零,您应该减去一个,我认为使用时间戳计算增量更简单:

function getDayDelta(incomingYear,incomingMonth,incomingDay){
  var incomingDate = new Date(incomingYear,incomingMonth-1,incomingDay),
      today = new Date(), delta;
  // EDIT: Set time portion of date to 0:00:00.000
  // to match time portion of 'incomingDate'
  today.setHours(0);
  today.setMinutes(0);
  today.setSeconds(0);
  today.setMilliseconds(0);

  // Remove the time offset of the current date
  today.setHours(0);
  today.setMinutes(0);

  delta = incomingDate - today;

  return Math.round(delta / 1000 / 60 / 60/ 24);
}


getDayDelta(2008,8,18); // -365
getDayDelta(2009,8,18); // 0
getDayDelta(2009,9,18); // 31

Answer 2

(2009,8,18)不是8月18日.现在是9月18日.

Answer 3

您可以在每个日期对象上调用getTime(),然后从较早的对象中减去后面的内容.这将为您提供两个对象之间的毫秒数差异.从那里,很容易到达几天.

但要注意几个小问题:1)夏令时,以及2)确保您的时间来自同一时区.