JS中的日期值是datetime值。

因此，直接日期计算是不一致的:

(2013-11-05 00:00:00) - (2013-11-04 10:10:10) < 1 day

例如，我们需要转换第2个日期:

(2013-11-05 00:00:00) - (2013-11-04 00:00:00) = 1 day

该方法可以在两个日期截断轧机:

var date1 = new Date('2013/11/04 00:00:00'); var date2 = new Date('2013/11/04 10:10:10'); //less than 1 var start = Math.floor(date1.getTime() / (3600 * 24 * 1000)); //days as integer from.. var end = Math.floor(date2.getTime() / (3600 * 24 * 1000)); //days as integer from.. var daysDiff = end - start; // exact dates console.log(daysDiff); date2 = new Date('2013/11/05 00:00:00'); //1 var start = Math.floor(date1.getTime() / (3600 * 24 * 1000)); //days as integer from.. var end = Math.floor(date2.getTime() / (3600 * 24 * 1000)); //days as integer from.. var daysDiff = end - start; // exact dates console.log(daysDiff);

使用毫秒时要小心。

date.getTime()返回毫秒，用毫秒做数学运算需要包含

日光节约时间(DST) 检查两个日期的时间是否相同(小时，分钟，秒，毫秒) 请确定需要哪些天数差异:2016年9月19日- 2016年9月29日= 1天或2天的差异?

上面评论中的例子是我迄今为止找到的最好的解决方案 https://stackoverflow.com/a/11252167/2091095。但是，如果你想计算所有涉及的天数，则对其结果使用+1。

function treatAsUTC(date) {
    var result = new Date(date);
    result.setMinutes(result.getMinutes() - result.getTimezoneOffset());
    return result;
}

function daysBetween(startDate, endDate) {
    var millisecondsPerDay = 24 * 60 * 60 * 1000;
    return (treatAsUTC(endDate) - treatAsUTC(startDate)) / millisecondsPerDay;
}

var diff = daysBetween($('#first').val(), $('#second').val()) + 1;

下面的解决方案将假设这些变量在代码中可用:

const startDate  = '2020-01-01';
const endDate    = '2020-03-15';

原生 JS

步骤:

设定开始日期 设定结束日期 计算的区别 将毫秒转换为天

const diffInMs   = new Date(endDate) - new Date(startDate)
const diffInDays = diffInMs / (1000 * 60 * 60 * 24);

备注:

我知道这不是你问题的一部分，但一般来说，我不建议在香草JavaScript中做任何日期计算或操作，而是使用date-fns, Luxon或moment.js这样的库，因为有许多边缘情况。

这个简单的JavaScript回答以十进制数计算天数。此外，在使用夏令时时，它可能会遇到边缘情况

使用图书馆

- 日期-fns

const differenceInDays = require('date-fns/differenceInDays');
const diffInDays = differenceInDays(new Date(endDate), new Date(startDate));

文档:https://date-fns.org/v2.16.1/docs/differenceInDays

——国际光子

const { DateTime } = require('luxon');
const diffInDays = DateTime.fromISO(endDate).diff(DateTime.fromISO(startDate), 'days').toObject().days;

文档:https://moment.github.io/luxon/docs/class/src/datetime.js DateTime.html # instance-method-diff

——Moment.js

const moment = require('moment');
const diffInDays = moment(endDate).diff(moment(startDate), 'days');

文档:https://momentjs.com/docs/ / /显示/不同

RunKit示例

我建议使用moment.js库(http://momentjs.com/docs/#/displaying/difference/)。它正确地处理夏令时，通常是很好的工作。

例子:

var start = moment("2013-11-03");
var end = moment("2013-11-04");
end.diff(start, "days")
1

我从其他答案中得到一些灵感，使输入具有自动卫生。我希望这是对其他答案的改进。

我还推荐使用<input type="date">字段，这将有助于验证用户输入。

//use best practices by labeling your constants. let MS_PER_SEC = 1000 , SEC_PER_HR = 60 * 60 , HR_PER_DAY = 24 , MS_PER_DAY = MS_PER_SEC * SEC_PER_HR * HR_PER_DAY ; //let's assume we get Date objects as arguments, otherwise return 0. function dateDiffInDays(date1Time, date2Time) { if (!date1Time || !date2Time) return 0; return Math.round((date2Time - date1Time) / MS_PER_DAY); } function getUTCTime(dateStr) { const date = new Date(dateStr); // If use 'Date.getTime()' it doesn't compute the right amount of days // if there is a 'day saving time' change between dates return Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()); } function calcInputs() { let date1 = document.getElementById("date1") , date2 = document.getElementById("date2") , resultSpan = document.getElementById("result") ; if (date1.value && date2.value && resultSpan) { //remove non-date characters console.log(getUTCTime(date1.value)); let date1Time = getUTCTime(date1.value) , date2Time = getUTCTime(date2.value) , result = dateDiffInDays(date1Time, date2Time) ; resultSpan.innerHTML = result + " days"; } } window.onload = function() { calcInputs(); }; //some code examples console.log(dateDiffInDays(new Date("1/15/2019"), new Date("1/30/2019"))); console.log(dateDiffInDays(new Date("1/15/2019"), new Date("2/30/2019"))); console.log(dateDiffInDays(new Date("1/15/2000"), new Date("1/15/2019"))); <input type="date" id="date1" value="2000-01-01" onchange="calcInputs();" /> <input type="date" id="date2" value="2022-01-01" onchange="calcInputs();"/> Result: <span id="result"></span>

试试这个

let today = new Date(). toisostring()。片(0,10) const startDate = '2021-04-15'; const endDate = today; const diffInMs = new Date(endDate) - new Date(startDate) const diffInDays = diffInMs / (1000 * 60 * 60 * 24); alert(diffInDays);