javascript returns 1 hour behind calendar date

Question

I have the below javascript to retrieve Start date time and an End date time for an event.

while(liEnum.moveNext())
{
    var oLiCal=liEnum.get_current();  
    var localDate =  moment();                               
    var eventDate = oLiCal.get_item("EventDate");
    var eventEndDate = oLiCal.get_item("EndDate");
    var eventAllDayEvent = oLiCal.get_item('fAllDayEvent');
    var eventCompanyWideEvent = oLiCal.get_item('CompanyWideEvent');

    console.log("local date: " + localDate.format('YYYY-MM-DD hh:mm a') );
    console.log("Event Start date: " + moment(eventDate).format('YYYY-MM-DD hh:mm a'));
    console.log("Event End date: " + moment(eventEndDate).format('YYYY-MM-DD hh:mm a'));

The calendar has the following date and times of an event:

The console log shows the following:

As we can see the date start and end times retrieved via javascript is 1 hour behind. Can any one please tell why that would be the case, and how can I get the exact date time from the server.

Much Obliged.

Answer 1

SharePoint displays date/time according to TimeZone in Regional Settings but returns in UTC format in JSOM.

Using SP.TimeZone.Information

The folloiwing example demonstrates how to retrieve time zone offset using SP.TimeZone.Information and then convert to SharePoint date/time using moment().zone():

var listTitle = 'Calendar';

var context = SP.ClientContext.get_current();
var web = context.get_web();
var list = web.get_lists().getByTitle(listTitle);
var item = list.getItemById(1);
context.load(item);

var timeZone = web.get_regionalSettings().get_timeZone();
context.load(timeZone);

context.executeQueryAsync(
 function() {
    var eventDate = item.get_item('EventDate');
    var endDate = item.get_item('EndDate');

    var timeZoneOffset = getTimeZoneOffset(timeZone); //exract TimeZone Offset

    var localEventDate = moment(eventDate).zone(timeZoneOffset);
    var localEndDate = moment(endDate).zone(timeZoneOffset);


    console.log("Event Start date: " + localEventDate.format('YYYY-MM-DD hh:mm a'));
    console.log("Event End date: " + localEndDate.format('YYYY-MM-DD hh:mm a'));

  },
  logError
);  

function logError(sender,args)
{
    console.log(args.get_message());
}


function getTimeZoneOffset(timeZone)
{
   return  timeZone.get_information().get_bias() +    timeZone.get_information().get_daylightBias() + timeZone.get_information().get_standardBias();          
}

Using SP.TimeZone.utcToLocalTime

SP.TimeZone.utcToLocalTime Method - converts the specified DateTime value from Coordinated Universal Time (UTC) to local time

The following example demonstrates how to use SP.TimeZone.utcToLocalTime:

var listTitle = 'Calendar';

var context = SP.ClientContext.get_current();
var web = context.get_web();
var list = web.get_lists().getByTitle(listTitle);
var item = list.getItemById(1);
context.load(item);

var timeZone = web.get_regionalSettings().get_timeZone();
context.load(timeZone);


context.executeQueryAsync(
 function onSucceeded() {
    var eventDate = item.get_item('EventDate');
    var endDate = item.get_item('EndDate');

    var localEventDate = timeZone.utcToLocalTime(eventDate);
    var localEndDate = timeZone.utcToLocalTime(endDate);

    context.executeQueryAsync(
      function() {
          console.log(localEventDate.get_value());   
          console.log(localEndDate.get_value());   
      },
      logError       
    );

 },
 logError
);  

function logError(sender,args)
{
    console.log(args.get_message());
}