如何从javascript中的日期中减去分钟数？

Question

如何将此伪代码转换为工作js [不要担心结束日期的来源,除非它是一个有效的javascript日期].

var myEndDateTime = somedate;  //somedate is a valid js date  
var durationInMinutes = 100; //this can be any number of minutes from 1-7200 (5 days)

//this is the calculation I don't know how to do
var myStartDate = somedate - durationInMuntes;

alert("The event will start on " + myStartDate.toDateString() + " at " + myStartDate.toTimeString());

Answer 1

一旦你知道这个:

• 您可以Date通过从1970年1月1日起以毫秒为单位调用构造函数来创建.
• 在valueOf()一个Date是自1970年1月1日的毫秒数
• 60,000一分钟内有毫秒: - ]

......这不是那么难.

在下面的代码中,Date通过从以下代码中减去适当的毫秒数来创建new myEndDateTime:

var MS_PER_MINUTE = 60000;
var myStartDate = new Date(myEndDateTime - durationInMinutes * MS_PER_MINUTE);

Answer 2

您还可以使用get和set分钟来实现它:

var endDate = somedate;

var startdate = new Date(endDate);

var durationInMinutes = 20;

startdate.setMinutes(endDate.getMinutes() - durationInMinutes);

Answer 3

一切都只是滴答,没有必要记住方法 ......

var aMinuteAgo = new Date( Date.now() - 1000 * 60 );

要么

var aMinuteLess = new Date( someDate.getTime() - 1000 * 60 );

更新

在使用momentjs之后,我不得不说这是一个很棒的图书馆,你应该看看.确实,在许多情况下,刻度线可以使您的代码非常小,并且您应该尝试使您的代码尽可能小,以满足您的需要.但对于任何复杂的事情,请使用momentjs.

Answer 4

moment.js有一些很好的方便方法来操作日期对象

该.subtract方法,允许用户从一个日期减去一定量的时间单位,通过提供量,和一个TIMEUNIT字符串.

var now = new Date();
// Sun Jan 22 2017 17:12:18 GMT+0200 ...
var olderDate = moment(now).subtract(3, 'minutes').toDate();
// Sun Jan 22 2017 17:09:18 GMT+0200 ...

Answer 5

尝试如下：

var dt = new Date();
dt.setMinutes( dt.getMinutes() - 20 );
console.log('#####',dt);

Answer 6

这是我发现的：

//First, start with a particular time
var date = new Date();

//Add two hours
var dd = date.setHours(date.getHours() + 2);

//Go back 3 days
var dd = date.setDate(date.getDate() - 3);

//One minute ago...
var dd = date.setMinutes(date.getMinutes() - 1);

//Display the date:
var monthNames = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var date = new Date(dd);
var day = date.getDate();
var monthIndex = date.getMonth();
var year = date.getFullYear();
var displayDate = monthNames[monthIndex] + ' ' + day + ', ' + year;
alert('Date is now: ' + displayDate);

资料来源：

http://www.javascriptcookbook.com/article/Perform-date-manipulations-based-on-adding-or-subtracting-time/

/sf/answers/895878931/

Answer 7

var date=new Date();

//here I am using "-30" to subtract 30 minutes from the current time.
var minute=date.setMinutes(date.getMinutes()-30); 

console.log(minute) //it will print the time and date according to the above condition in Unix-timestamp format.

您可以使用。new Date()例如将Unix时间戳转换为常规时间。

var extract=new Date(minute)
console.log(minute)//this will print the time in the readable format.