Google Spreadsheet datetime conversion

Question

I am trying to match two different responses of same Date field in Google Form
For that for one cell I am accessing its value from the spreadsheet generated by filling its response and for other I am accessing its value from the last response generated by filling second form
In first by observing log, it stored value in this format in spreadsheet
"Tue Jan 03 00:00:00 GMT+05:30 2017" (without quotes)
and other stored value in this format "2017-01-03"
And I want to compare these two values, I know if I access the spreadsheet of 2nd form it will be easy to compare but can I compare it in this format for which I don't need to access other form's spreadsheet?
Edit: I tried to compare cells of both spreadsheets but both of them also had different formats
In second spreadsheet format was like
"Thu Mar 16 2017 00:00:00 GMT+0530 (IST)"

Answer 1

The value "2017-01-03" is a string. It carries no information about a timezone with it, so it's something you need to know (from the context in which you collected the form). Perhaps it's Asia/Kolkata, the Indian time? If so, I would format the first date as the string, using the same timezone, and compare the two.

var str = "2017-01-03";     // date as string
var val = range.getValue(); // date as Date object, from spreadsheet
var val2str = Utilities.formatDate(val, 'Asia/Kolkata', 'yyyy-MM-dd'); // now also a string
Logger.log(str == val2str); // test equality

(One can also test inequalities on strings formatted in this way, str < val2str).

Another approach would be parse the second string into a date object, but this is somewhat more complicated as the Google Apps Script date parser is finicky.