使用时刻计算两个日期之间的天数

Question

我正在尝试使用以下代码计算 Javascript 中两个日期之间的天数。

    console.log(self.StartDate());
    var start = moment(self.StartDate(), "YYYY-MM-DD");
    console.log(start);
    console.log(self.EndDate());
    var end = moment(self.EndDate(), "YYYY-MM-DD");
    console.log(end);
    var duration = moment.duration(start.diff(end));
    console.log(duration);

    //no of days between start and end
    console.log(duration.asDays());

控制台输出：

Thu Jun 20 2019 01:00:00 GMT+0100 (British Summer Time)
n {_isAMomentObject: true, _i: Thu Jun 20 2019 01:00:00 GMT+0100 (British Summer Time), _f: "YYYY-MM-DD", _isUTC: false, _pf: {…}, …}_d: Wed Aug 19 0020 00:00:00 GMT-0001 (British Summer Time) {}_f: "YYYY-MM-DD"_i: Thu Jun 20 2019 01:00:00 GMT+0100 (British Summer Time) {}_isAMomentObject: true_isUTC: false_locale: r {_ordinalParse: /\d{1,2}(th|st|nd|rd)/, ordinal: ƒ, _abbr: "en", _ordinalParseLenient: /\d{1,2}(th|st|nd|rd)|\d{1,2}/}_pf: {empty: false, unusedTokens: Array(0), unusedInput: Array(3), overflow: 1, charsLeftOver: 49, …}__proto__: Object
Mon Jun 24 2019 15:10:41 GMT+0100 (British Summer Time)
n {_isAMomentObject: true, _i: Mon Jun 24 2019 15:10:41 GMT+0100 (British Summer Time), _f: "YYYY-MM-DD", _isUTC: false, _pf: {…}, …}
Ea {_milliseconds: -126230400000, _days: 0, _months: 0, _data: {…}, _locale: r}
-1461

self.StartDate() 是 20/06/2019 和 self.EndDate() 是 24/06/2019 所以我很高兴警报显示 4 但它显示 -1461。

为什么会这样？

Answer 1

问题是您的日期不是formatted the way you tell moment.js they are。 20/06/2019 是 DD/MM/YYYY 而不是 YYYY-MM-DD。根据文档，非数字字符将被忽略，因此 20/06/2019 将被解析为 2006-20-19。由于不存在这样的日期，Moment.js 会尝试猜测您的实际意思并提出2020-06-19：

var start = moment("20/06/2019", "YYYY-MM-DD");

console.log(start);

<script src="https://cdn.jsdelivr.net/momentjs/2.14.1/moment-with-locales.min.js"></script>

结束日期也会发生同样的事情。

您需要更改您告诉 Moment.js 的格式或修复开始和结束日期以使用您指定的格式，在这两种情况下，您都会得到正确的结果：

var self = {
    StartDate: () => "20/06/2019",
    EndDate: () => "24/06/2019"
}

var start = moment(self.StartDate(), "DD/MM/YYYY"); //using the correct format
var end = moment(self.EndDate(), "DD/MM/YYYY");
var duration = moment.duration(start.diff(end));

console.log(duration.asDays());

<script src="https://cdn.jsdelivr.net/momentjs/2.14.1/moment-with-locales.min.js"></script>

var self = {
    StartDate: () => "2019-06-20", //using dates in the correct format
    EndDate: () => "2019-06-24"
}

var start = moment(self.StartDate(), "YYYY-MM-DD");
var end = moment(self.EndDate(), "YYYY-MM-DD");
var duration = moment.duration(start.diff(end));

console.log(duration.asDays());

<script src="https://cdn.jsdelivr.net/momentjs/2.14.1/moment-with-locales.min.js"></script>

Answer 2

您的代码应该可以正常工作。您应该只在差异计算中交换 start 和 end 以获得正值。

var startDate = moment("2019-06-20", "YYYY-MM-DD");
var endDate = moment("2019-06-24", "YYYY-MM-DD");
var duration = moment.duration(startDate.diff(endDate));

//no of days between start and end
console.log(duration.asDays());


var duration = moment.duration(endDate.diff(startDate));
console.log(duration.asDays());

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.js"></script>

如果您只对以天计算的差异感兴趣，则此代码会更短：

var startDate = moment("2019-06-20", "YYYY-MM-DD");
var endDate = moment("2019-06-24", "YYYY-MM-DD");
var diff  = startDate.diff(endDate, 'days');
console.log(diff);


var diff  = endDate.diff(startDate, 'days');
console.log(diff);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.js"></script>

日期本身肯定有问题。
事实上，这就是你解析日期字符串的方式

// This is parsed as the 19th day of 6th month in year 2020
var startDate = moment("20/06/2019", "YYYY-MM-DD");
// This is parsed as the 19th day of 6th month in year 2024
var endDate = moment("24/06/2019", "YYYY-MM-DD");
var diff  = endDate.diff(startDate, 'days');
console.log({"start": startDate, "end": endDate, "diff": diff});

// You either need to change the date strings or the format strings
var startDate = moment("20/06/2019", "DD/MM/YYYY");
var endDate = moment("24/06/2019", "DD/MM/YYYY");
var diff  = endDate.diff(startDate, 'days');
console.log({"start": startDate, "end": endDate, "diff": diff});


// You either need to change the date strings or the format strings
var startDate = moment("2019-06-20", "YYYY-MM-DD");
var endDate = moment("2019-06-24", "YYYY-MM-DD");
var diff  = endDate.diff(startDate, 'days');
console.log({"start": startDate, "end": endDate, "diff": diff});

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.js"></script>

Answer 3

您的日期无效，您指定的开始日期是“20/06/2019”，它是“DD/MM/YYYY”的模板，但告诉时刻使用“YYYY-MM-DD”的模板。

你只需要替换你传递给 moment 的模板，这里有一个更简洁的方法：

const DEFAULT_DATE_TEMPLATE = "DD/MM/YYYY";

const getDaysBetweenDates = (date1, date2, dateTemplate = DEFAULT_DATE_TEMPLATE) => {
    const start = moment(date1, dateTemplate);
    const end = moment(date2, dateTemplate);
    const duration = moment.duration(start.diff(end));
    const daysDiff = duration.asDays();

    // for your example you will get -4, abs will make it into 4 for you
    return Math.abs(daysDiff); 
}


const myDiff = getDaysBetweenDates('20/06/2019', '24/06/2019');
console.log(myDiff); // 4

// or if you rather keep your other template
const myDiff2 = getDaysBetweenDates('2019-06-20', '2019-06-24', 'YYYY-MM-DD');
console.log(myDiff2); // 4