JS：如何比较从UTC到定义的时区的2个日期？

Question

I stored a string of UTC Date (without time):

var limitDateStr = "2017-07-04T00:00:00.000Z";

And a TIMEZONE in hours (based on this) , not in Zone Name (like America/Antigua)

var timezone = "-6.0"; //could be from -12.0 to 12.0 

The problem is: Verify if actual date, is greater than limitDate in the same Timezone.

---

What I Do with Moment.js

I Used moment for change the timezone, but when y change the offset. The date is changed too:

  var _expirationDateUTC = moment.utc(limitDateStr).utcOffset(parseFloat(timezone)).format();
  // "2017-07-03T18:00:00-06:00"

Instead of 2017-07-04T00:00:00-06:00

Actual date, works great: (except for Days Savings)

var today = moment.utc().utcOffset(parseFloat(timezone)).format();
//"2017-07-04T15:32:49-06:00"

And I want to compare... maybe with moment function:

today.isAfter(_expirationDateUTC);

but the expiration date is now working like expect.

Answer 1

Ok, there problem seems to be this:

var _expirationDateUTC = moment.utc(limitDateStr).utcOffset(parseFloat(timezone)).format();

where limitDateStr = "2017-07-04T00:00:00.000Z" ;

What you are doing up to this point is feeding moment with this date and then apply the timezone offset, which will substract the timezone(in this case -6) to the date you are actually feeding.

"2017-07-04T00:00:00.000Z" - 6 hours = "2017-07-03T18:00:00-06:00"

What you are looking for is not to calculate the limitDate in a different timezone but to have limitDate to be the same as the utc but in a different timezone.

So you need this block of code which will add the hours from the target zone:

var limitDateStr = moment("2017-07-04T00:00:00.000Z");
var timezone = "-6.0"

//Substract the timezone offset to the time;
//This should be: "2017-07-04T06:00:00.000Z"
limitDateStr.subtract({hours: parseFloat(timezone)});

//Now you can apply the offseting
//and this will become: "2017-07-04T00:00:00-06:00"
var _expirationDateUTC = moment.utc(limitDateStr).utcOffset(parseFloat(timezone)).format();

var today = moment.utc().utcOffset(parseFloat(timezone)).format();

var hasExpired = today.isAfter(_expirationDateUTC);

Answer 2

Primitive solution was: "add the difference in hours"

function validateDateBefore(date, timezone){
  /** enable this for end day limit **/
  //var _expirationDateUTC = moment.utc(date).utcOffset(parseFloat(timezone)).startOf('hour').add((parseFloat(timezone) * -1) + 23, 'hours').add(59, 'minute').add(59, 'second').format();
  var _expirationDateUTC = moment.utc(date).utcOffset(parseFloat(timezone)).startOf('hour').add((parseFloat(timezone) * -1), 'hours').format();
  var _todayUTC = moment.utc().utcOffset(parseFloat(timezone)).format();

  var today = moment(_todayUTC);
  var expiration = moment(_expirationDateUTC);

  return expiration.isAfter(today);
}