Convert JavaScript DateTime to UTC with no milliseconds - datetime

Question

Right now I'm trying to parse a date that's written in a human-readable format into a DateTime String that a SharePoint list will accept. In order to do this I've determined that I need a String in a format similar to ISO that looks like: 2007-08-20T00:00:00Z. It seems that SharePoint only accepts DateTimes that are in UTC with no milliseconds included (for whatever reason, SharePoint gives errors and won't accept the DateTime when you include the milliseconds), so I need to convert my local time into a UTC time before converting it to the ISO string.
Here's the process that the code below is using.
First I use DateJS to parse my human-date into a JavaScript Date.
(Works fine, but apparently DateJS has been abandoned, so maybe I
should change this to use MomentJS.)
Next I tried to create a new
moment in UTC. (This line is very, very wrong, and crashes my
program.)
Then I have SPServices convert it into an ISO. SPServices drops the milliseconds off the DateTime so that SharePoint will accept it. (Works
fine).
I'm sure there has to be a more elegant/working way to achieve this, instead of stitching together 3 different libraries. I'm just not sure what it is.
var jScriptStartDate = Date.parse("6/29/2014 8:30am"); //JS Date
var jScriptStartDateUTC = moment(jScriptStartDate).utc(); //local date to UTC.
var startDate = $().SPServices.SPConvertDateToISO({ //Sharepoint ISO 8601 format
dateToConvert: jScriptStartDateUTC,
dateOffset: "" //Sharepoint dates only accept UTC times, aka no dateOffset.
});
newItem.set_item('EventDate', startDate); //EventDate is internal for StartTime

Answer 1

You can just use moment.js, and this is all in the documentation.
moment('6/29/2014 8:30am','M/D/YYYY h:mma').toISOString()
This assumes all of the following:
The source value is in the user's time zone (that is - the time zone of the machine where the JavaScript code is running)
The input will always be in the specified format
It's also worth mentioning that if you put a space before the "am", that most modern browsers can do this natively without any library:
new Date('6/29/2014 8:30 am').toISOString()
If you take that approach, realize that the date parts are ordered according to the users locale, which might be m/d/y, or d/m/y or y/m/d.
Also, you said in the title "... with no milliseconds", but didn't elaborate on that in your question. I'm fairly certain you can pass the milliseconds without issue. There's no good reason to go out of your way to remove them. But if you must, then that would be like this with moment:
moment('6/29/2014 8:30am','M/D/YYYY h:mma').utc().format('YYYY-MM-DD[T]HH:mm:ss[Z]')

Answer 2

I ended up adjusting this code to use the updated DateJS (https://github.com/abritinthebay/datejs/) and a custom function I made called .toShortISOString().
The process is down to 3 lines:
var jScriptStartDate = Date.parse("6/28/2014 8:00am"); //convert to Javascript Date
var startDate = jScriptStartDate.toShortISOString(); //convert to Sharepoint ISO format (UTC with no milliseconds)
newItem.set_item('EventDate', startDate); //Strangely the internal name for Start Time is EventDate
.toShortISOString()'s main change is the removal of milliseconds, since SharePoint doesn't like milliseconds. It's code looks like this inside of the date.js file:
if ( !$P.toShortISOString ) {
$P.toShortISOString = function() {
return this.getUTCFullYear() +
"-" + p(this.getUTCMonth() + 1) +
"-" + p(this.getUTCDate()) +
"T" + p(this.getUTCHours()) +
":" + p(this.getUTCMinutes()) +
":" + p(this.getUTCSeconds()) +
//Remove the milliseconds.
//"." + String( (this.getUTCMilliseconds()/1000).toFixed(3)).slice(2, 5) +
"Z";
};
}
If you're trying to add this to date.js, make sure you have the latest version from the link above, then search the file for toISOString and place the code right below the handler for toISOString.