How can I check if a [recurring] event is occurring *right now* using JavaScript?

Question

I have a site with a calendar. In the calendar I have a mix of recurring and non-recurring events.

On a WebPart page I have a CEWP that uses WebServices (_vti_bin/Lists.asmx?op=GetListItems) through JavaScript to get a list of those events for a specific month (a la https://sharepoint.stackexchange.com/questions/160778/daterangesoverlap-to-show-events-for-last-month-in-a-dvwp). So I have a list of dates like so:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="..." xmlns:xsi="..." xmlns:xsd="...">
    <soap:Body>
        <GetListItemsResponse xmlns="...">
            <GetListItemsResult>
                <listitems xmlns:s='...' xmlns:dt='...' xmlns:rs='...' xmlns:z='...'>
                    <rs:data ItemCount="1">
                        <z:row
                            ows_Title='recurring meeting one'
                            ows_EventDate='2016-01-26 11:00:00'
                            ows_EndDate='2016-01-26 12:00:00'
                            ows_Description='...'
                            ows_fRecurrence='1'
                            ows_RecurrenceData='...'
                            ows_fAllDayEvent='0'
                            ows__ModerationStatus='0'
                            ows__Level='1'
                            ows_ID='2.0.2016-01-26T16:00:00Z'
                            ows_UniqueId='...'
                            ows_owshiddenversion='2'
                            ows_FSObjType='2;#0'
                            ows_Created='2015-10-22 08:34:47'
                            ows_PermMask='0x7fffffffffffffff'
                            ows_Modified='2015-10-22 09:22:05'
                            ows_FileRef='2;#/xxx/Lists/Meeting Calendar/2_.000'
                            ows_MetaInfo='2;#' />
                    </rs:data>
                </listitems>
            </GetListItemsResult>
        </GetListItemsResponse>
    </soap:Body>
</soap:Envelope>

What I'm trying to do now is iterate over each event to see if it is occurring right now.

I could use new Date() to get the date now, but that would be for the client's timezone/settings. The SharePoint site may use a different regional setting. And, the user's regional settings may inherit from the site or the user may have their own regional setting -- both of which would effect the output from the GetListItems call.

Ideally I'd love a way to get the current time accounting for, in order:

• the user's regional settings
• the site's regional settings if the user is inheriting from the site

Any thoughts/ideas?

Answer 1

I was able to do what I needed by using the ows_ID attribute of the event. It has the start time in UTC in it; something like 3.0.2015-11-25T22:00:00Z. The ows_EventDate has the time taking into account all the regional settings. Using some simple math I was able to do what I needed.

// get the ID (e.g. 3.0.2015-11-25T22:00:00Z), split to get the start time part, remove the T and Z and parse into a Date object
var eventStartDateUTC = new Date(rows[i].getAttribute("ows_ID").split(/\./g)[2].slice(0,-1).replace(/T/, " ").replace(/-/g, "/")).getTime();

// get the start time after all regional settings are applied
var eventStartDate = new Date(rows[i].getAttribute("ows_EventDate").replace(/-/g, "/")).getTime();

// find the UTC offset
var serverUTCOffset = eventStartDate - eventStartDateUTC;

// get the end time after all regional settings are applied
var eventEndDate = new Date(rows[i].getAttribute("ows_EndDate").replace(/-/g, "/")).getTime();

// find the end time in UTC using the previously calculated offset
var eventEndDateUTC = eventEndDate - serverUTCOffset;

// get the time now
var now = new Date();

// calculate the offset to get the UTC time
now = now.getTime() + (now.getTimezoneOffset() * 60 * 1000);

if(now >= eventStartDateUTC && now <= eventEndDateUTC) 
{
    // active event
}