Dealing with (birthday) dates and Timezone with Dojo - date

Question

I have a simple widget that has:
<input class="input" id="${id}_dateOfBirth" name="dateOfBirth" data-dojo-type="dijit/form/DateTextBox" />
Note that it's a birthday. So, it's meant to stay the same, regardless of where you are when you are (timezone shouldn't happen). If you are born on the 10th of January at 3:00AM in England, and view your personal information from New York, you are meant to still see 10th of January, NOT the 9th!
I am in GMT+8 right now.
When I submit this form, this actually gets to the server when I put in 1/1/1970:
dateOfBirth: "1969-12-31T16:00:00.000Z"
Which is bad, because it's 8 hours short of the actual date.
Basically, I need a way for the DateTextBox to show the date as it came from the server, effectively ignoring the browser's timezone.

Answer 1

FWIW, here is my variant of UTCDateTextBox:
define([
"dojo/_base/declare",
"dijit/form/DateTextBox"
], function(declare, DateTextBox) {
function isValidDate(value) {
return value instanceof Date && isFinite(value.getTime());
}
function toUTCDate(value) {
if (isValidDate(value)) {
value = new Date(
Date.UTC(value.getFullYear(), value.getMonth(), value.getDate())
);
}
return value;
}
return declare(DateTextBox, {
_getValueAttr : function() {
return toUTCDate(this.inherited("_getValueAttr", arguments));
}
});
});
For my use case, I found that I didn't need to override _setValueAttr(). With the above implementation, when getUTCXXX(), toUTCString(), toISOString() or toJSON() are called on the date object returned from _getValueAttr(), then the correct UTC date with zeroed time elements is returned.
Hope this helps.

Answer 2

After much hacking and analysing Dojo's source code, I came up with this:
var UTCDateTextBox = declare( 'UTCDateTextBox', [ DateTextBox ], {
_getValueAttr: function(){
var ov = this.inherited(arguments);
if( ov ){
ov.setTime( ov.getTime() - ov.getTimezoneOffset() * 60 * 1000 );
}
return ov;
},
_setValueAttr: function( value, priorityChange, formattedValue){
var v = stamp.fromISOString( value );
if( v ){
v.setTime( v.getTime() + v.getTimezoneOffset() * 60 * 1000 );
value = v;
}
this.inherited(arguments);
}
});
Basically:
When the value is set, the timezone difference gets added. This means that if the server has 1979-12-25T00:00:00.000Z, rather than assigning Tue Dec 25 1979 08:00:00 GMT+0800 (WST), it will assign Tue Dec 25 1979 00:00:00 GMT+0800 (WST) . Basically, the date is converted locally to whatever it was in UTC.
When the value is parsed, it will be changed from Tue Dec 25 1979 00:00:00 GMT+0800 (WST) to Tue Dec 25 1979 08:00:00 GMT+0800 (WST)
The changed value is the one submitted to the server. So, it will be correct regardless of what timezone it will be edited at.
Since I only ever ever deal with dates, if the server has 1979-12-31T23:00:00Z (which is an error: for birthdays, the time is actually ignored and mustn't matter), this will happen:
When the value is set, ISO is 1979-12-31T23:00:00.000Z. So, Tue Jan 01 1980 07:00:00 GMT+0800 (WST) is changed into Mon Dec 31 1979 23:00:00 GMT+0800 (WST). This means that the right date is placed into the date textbox (31/12/1979).
When the value is parsed from the textbox, Mon Dec 31 1979 00:00:00 GMT+0800 (WST) becomes Mon Dec 31 1979 08:00:00 GMT+0800 (WST). So, the server will save 1979-12-31T00:00:00Z -- which is, again, the correct date!
If there are bettere solutions, please let me know. Frankly, I hope there are as this one feels like a bit of a cheat!