如何计算两个日期之间的天数?

下面是一个函数:

function days_between(date1, date2) {


// The number of milliseconds in one day
const ONE_DAY = 1000 * 60 * 60 * 24;


// Calculate the difference in milliseconds
const differenceMs = Math.abs(date1 - date2);


// Convert back to days and return
return Math.round(differenceMs / ONE_DAY);


}

const oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
const firstDate = new Date(2008, 1, 12);
const secondDate = new Date(2008, 1, 22);


const diffDays = Math.round(Math.abs((firstDate - secondDate) / oneDay));

调整以允许夏令时的差异。试试这个:

  function daysBetween(date1, date2) {


// adjust diff for for daylight savings
var hoursToAdjust = Math.abs(date1.getTimezoneOffset() /60) - Math.abs(date2.getTimezoneOffset() /60);
// apply the tz offset
date2.addHours(hoursToAdjust);


// The number of milliseconds in one day
var ONE_DAY = 1000 * 60 * 60 * 24


// Convert both dates to milliseconds
var date1_ms = date1.getTime()
var date2_ms = date2.getTime()


// Calculate the difference in milliseconds
var difference_ms = Math.abs(date1_ms - date2_ms)


// Convert back to days and return
return Math.round(difference_ms/ONE_DAY)


}


// you'll want this addHours function too


Date.prototype.addHours= function(h){
this.setHours(this.getHours()+h);
return this;
}

我为另一篇文章写了这个解决方案，他问我如何计算两个日期之间的差异，所以我分享了我准备的:

// Here are the two dates to compare
var date1 = '2011-12-24';
var date2 = '2012-01-01';


// First we split the values to arrays date1[0] is the year, [1] the month and [2] the day
date1 = date1.split('-');
date2 = date2.split('-');


// Now we convert the array to a Date object, which has several helpful methods
date1 = new Date(date1[0], date1[1], date1[2]);
date2 = new Date(date2[0], date2[1], date2[2]);


// We use the getTime() method and get the unixtime (in milliseconds, but we want seconds, therefore we divide it through 1000)
date1_unixtime = parseInt(date1.getTime() / 1000);
date2_unixtime = parseInt(date2.getTime() / 1000);


// This is the calculated difference in seconds
var timeDifference = date2_unixtime - date1_unixtime;


// in Hours
var timeDifferenceInHours = timeDifference / 60 / 60;


// and finaly, in days :)
var timeDifferenceInDays = timeDifferenceInHours  / 24;


alert(timeDifferenceInDays);

你可以跳过代码中的一些步骤，我写它是为了让它容易理解。

你会在这里找到一个运行的例子:http://jsfiddle.net/matKX/

这是我用的。如果只是减去日期，它将无法跨越夏令时边界(例如4月1日至4月30日或10月1日至10月31日)。这省去了所有的小时，以确保您有一天的时间，并通过使用UTC消除了任何DST问题。

var nDays = (    Date.UTC(EndDate.getFullYear(), EndDate.getMonth(), EndDate.getDate()) -
Date.UTC(StartDate.getFullYear(), StartDate.getMonth(), StartDate.getDate())) / 86400000;

作为函数:

function DaysBetween(StartDate, EndDate) {
// The number of milliseconds in all UTC days (no DST)
const oneDay = 1000 * 60 * 60 * 24;


// A day in UTC always lasts 24 hours (unlike in other time formats)
const start = Date.UTC(EndDate.getFullYear(), EndDate.getMonth(), EndDate.getDate());
const end = Date.UTC(StartDate.getFullYear(), StartDate.getMonth(), StartDate.getDate());


// so it's safe to divide by 24 hours
return (start - end) / oneDay;
}

用我的日期差计算器:

var startDate = new Date(2000, 1-1, 1);  // 2000-01-01
var endDate =   new Date();              // Today


// Calculate the difference of two dates in total days
function diffDays(d1, d2)
{
var ndays;
var tv1 = d1.valueOf();  // msec since 1970
var tv2 = d2.valueOf();


ndays = (tv2 - tv1) / 1000 / 86400;
ndays = Math.round(ndays - 0.5);
return ndays;
}

所以你可以调用:

var nDays = diffDays(startDate, endDate);

(完整源代码位于http://david.tribble.com/src/javascript/jstimespan.html。)

齿顶高

代码可以通过更改以下几行来改进:

  var tv1 = d1.getTime();  // msec since 1970
var tv2 = d2.getTime();

这是我的实现:

function daysBetween(one, another) {
return Math.round(Math.abs((+one) - (+another))/8.64e7);
}

+<date>对整数表示进行类型强制转换，其效果与<date>.getTime()和8.64e7是一天中的毫秒数相同。