Develop Reference

Javascript - Comparing dates without time

I am trying to compare two dates in javascript without the time portions. The first date comes from a jquery datepicker and the second date comes from a string.
Although I could swear that my method worked a while ago it looks like it is not working now.
My browser is Firefox but I also need my code to work in IE.
function selectedDateRetentionDaysElapsed() {
var dateSelectedDate = $.datepicker.parseDate('dd/mm/yy', $('#selectedDate').val());
// dateSelectedDate is equal to date 2015-09-30T14:00:00.000Z
var parsedRefDate = isoStringToDate('2015-11-10T00:00:00');
var reportingDate = getPredfinedDateWithoutTime(parsedRefDate);
// reportingDate is equal to date 2015-11-10T13:00:00.000Z
var businessDayCountFromCurrentReportingDate = getBusinessDayCount(dateSelectedDate,reportingDate);
// businessDayCountFromCurrentReportingDate is equal to 39.9583333333336
if (businessDayCountFromCurrentReportingDate >= 40) {
return true;
}
return false;
}
function isoStringToDate(dateStr) {
var str = dateStr.split("T");
var date = str[0].split("-");
var time = str[1].split(":");
//constructor is new Date(year, month[, day[, hour[, minutes[, seconds[, milliseconds]]]]]);
return new Date(date[0], date[1]-1, date[2], time[0], time[1], time[2], 0);
}
function getPredfinedDateWithoutTime(myDate) {
myDate.setHours(0,0,0,0)
return myDate;
}
My issues are...
My isoStringToDate function is returning a date with a time even though I am not specifying a time.
The setHours call on a date does not seem to be working either.
Can someone please help me with this.

The simplest way to get the number of whole days between two dates is to create two date objects for the subject dates that are set to the same time. Noon is convenient as it means the date part is unaffected by daylight saving (some places introduce it at midnight) if you happen to print out just the date part.
The following does all calculations in the time zone of the host system. UTC could be used (and the hours set to 0 as daylight saving isn't an issue at all), but it's more to type.
E.g.:
function differenceInDays(d0, d1) {
// Copy dates so don't affect originals
d0 = new Date(+d0);
d1 = new Date(+d1);
// Set to noon
d0.setHours(12,0,0,0);
d1.setHours(12,0,0,0);
// Get difference in whole days, divide by milliseconds in one day
// and round to remove any daylight saving boundary effects
return Math.round((d1-d0) / 8.64e7)
}
// Difference between 2015-11-12T17:35:32.124 and 2015-12-01T07:15:54.999
document.write(differenceInDays(new Date(2015,10,12,17,35,32,124),
new Date(2015,11,01,07,15,54,999)));

Google Form on Submit get values and format the time

I am using Google Apps Script with a Google form. When the user submits the Google Form I get a value from a question. I then take that value and make it a date object, from what I saw on this post about daylight savings I use that to determine the timezone. I run the date object through Utilities.formatDate and want to get the correctly formatted date.
example: 9:00 AM
But instead I am getting a completely different time than expected.
My question is: Can someone help me understand why the below code is outputting a time that is 3 hours different?
function onSubmit(e) {
var values = e.values;
Logger.log(values);
try {
var start1 = new Date(values[3]);
var startN = new Date(start1).toString().substr(25,6)+"00";
var startT = Utilities.formatDate(start1, startN, "h:mm a");
Logger.log(startT);
} catch(error) {
Logger.log(error);
}
}

The assumption that Utilities formatDate does not support GMT... parameter is not true.
The post you mentioned in reference is used to get calendar events and is a useful way to get the right value when you get events from another daylight saving period (getting the TZ info from the calendar event itself), for example events for next month will be in "summer time" while we are still in "winter time"...
Your issue might come from different sources depending on time zone settings of your script vs timezone of the source. Could you describe the exact configuration in which you use this script ?
In the mean time, here is a small code that demonstrates how the code is working + the logger results :
function testOnSubmit() {
var eventInfo = {};
var values = {};
values['3'] = new Date();
eventInfo['values'] = values;
Logger.log('eventInfo = '+JSON.stringify(eventInfo)+'\n\n');
onSubmit(eventInfo);
}
function onSubmit(e) {
var values = e.values;
try {
var start1 = new Date(values[3]);
Logger.log('onSubmit log results : \n');
Logger.log('start1 = '+start1)
var startN = new Date(start1).toString().substr(25,6)+"00";
Logger.log('startN = '+startN);
var startT = Utilities.formatDate(start1, startN, "h:mm a");
Logger.log('result in timeZone = '+startT);
} catch(error) {
Logger.log(error);
}
}
EDIT : additionally, about the 30 and 45' offset, this can easily be solved by changing the substring length like this :
var startN = new Date(start1).toString().substr(25,8);
the result is the same, I had to use the other version a couple of years ago because Google changed the Utilities.formatDate method at some moment (issue 2204) but this has been fixed.
EDIT 2 : on the same subject, both methods actually return the same result, the GMT string has only the advantage that you don't have to know the exact timezone name... there is also the Session.getScriptTimeZone() method. Below is a demo script that shows the resulst for 2 dates in January and July along with the log results :
function testOnSubmit() {
var eventInfo = {};
var values = {};
values['3'] = new Date(2014,0,1,8,0,0,0);
eventInfo['values'] = values;
Logger.log('eventInfo = '+JSON.stringify(eventInfo)+'\n\n');
onSubmit(eventInfo);
values['3'] = new Date(2014,6,1,8,0,0,0);
eventInfo['values'] = values;
Logger.log('eventInfo = '+JSON.stringify(eventInfo)+'\n');
onSubmit(eventInfo);
}
function onSubmit(e) {
var values = e.values;
var start1 = new Date(values[3]);
Logger.log('onSubmit log results : ');
Logger.log('start1 = '+start1)
var startN = new Date(start1).toString().substr(25,8);
Logger.log('startN = '+startN);
Logger.log('result in timeZone using GMT string = '+Utilities.formatDate(start1, startN, "MMM,d h:mm a"));
Logger.log('result in timeZone using Joda.org string = '+Utilities.formatDate(start1, 'Europe/Brussels', "MMM,d h:mm a"));
Logger.log('result in timeZone using Session.getScriptTimeZone() = '+Utilities.formatDate(start1, Session.getScriptTimeZone(), "MMM,d h:mm a")+'\n');
}
Note also that the Logger has its own way to show the date object value ! it uses ISO 8601 time format which is UTC value.

Try this instead:
var timeZone = Session.getScriptTimeZone();
var startT = Utilities.formatDate(start1, timeZone, "h:mm a");
The Utilities.formatDate function expects a time zone that is a valid IANA time zone (such as America/Los_Angeles), not a GMT offset like GMT+0700.
I am making the assumption that Session.getScriptTimeZone() returns the appropriate zone. If not, then you might need to hard-code a specific zone, or use a different function to determine it.
Additionally, the +"00" in the script you had was assuming that all time zones use whole-hour offsets. In reality, there are several that have 30-minute or 45-minute offsets.

Javascript - Convert ####-##-## to Epoch time

Is there a way to take a date object from a HTML object in the format of ####-##-## and convert it to epoch time. For example, the user inputs the value of August 12, 2012 which shows as 2012-08-12 when I print out the .val() of it, and I need to get this in Epoch time.
EDIT
Code to date:
if (hvStartDate == "") {
hvStartDate = "start"
}
else {
console.log($("#hv-start-date").val()); // => 2012-08-20
hvStartDate = new Date($("#hv-start-date").val()).getTime(); // => NaN
}
if (hvEndDate == "") {
hvEndDate = "end"
}
else {
hvEndDate = new Date($("#hv-end-date").val()).getTime(); // => NaN
}
var myTmp = new Date("2012-08-20");
console.log(myTmp.getTime()); // => NaN

Javascript's Date built-in allows you to pass a date string into its constructor, giving you a Date based on that string. From there, calling getTime( ) will give you the epoch time.
new Date($('.user-value').val()).getTime(); // => epoch time
new Date('2012-08-12').getTime(); // 1344729600000
Caveat: Beware of locale strings and locale-specific date formatting (for example, the position of days and months switch depending on locale).
EDIT: Based on your code in the comment below, here's what you need to do. Notice that you have to instantiate a new Date Object before calling getTime():
if (hvStartDate == "") {
hvStartDate = "start"
}
else {
hvStartDate = new Date($("#hv-start-date").val()).getTime();
}

Simply use the getTime() function. It returns the number of milliseconds since Epoch :
var msSinceEpoch = myDate.getTime();
Complete Date reference at MDN : https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Date
EDIT : if you have to parse it too, you may :
use new Date(theString) if it has the good format
set yourself the different date fields (see reference) after having parsed it
use a date parsing library. I use this one : http://www.datejs.com/ which is very powerful for all date parsing, computing and formating.

creating date from a timestring in javascript

I am new to javascript and am trying to compare two date values ,I am getting two time value strings in the format
06:30:47 AM
01:10:47 PM
I need to compare these to find out if the first one is less than the other.I couldn't figure out how to do this in javascript.Can someone help?
o.h

I do not think that the standard implementation can parse this. I would do something like this:
function toDate(dateString) {
var timeComponents = dateString.replace(/\s.*$/, '').split(':');
if (dateString.indexOf("PM") > -1) {
timeComponents[0] += 12;
}
var date = new Date();
date.setHours(timeComponents[0]);
date.setMinutes(timeComponents[1]);
date.setSeconds(timeComponents[2]);
return date;
}
if (toDate('06:30:47 AM') > toDate('01:10:47 PM')) {
// ...
}

JavaScript's specified date/time parsing, what you can rely upon cross-browser, is surprisingly limited. For a long time, there was no single string date format that was mandated in the spec, and as of the recent 5th edition spec, the only mandated format is ISO-8601 (and some subsets). You can't yet rely on browsers having implemented that part of the 5th edition spec.
So you have a couple of choices:
Parse the string yourself and use the Date constructor that takes the individual parts of the date as numbers, e.g. new Date(year, month, day, hour, minute, second, ...). (You need only specify as many of those as you want, so for instance new Date(2010, 9, 14) is September 14th, 2010.)
Use a library like Moment that's already done the work for you. Moment lets you specify the format to parse.

Use the Date object. Check this: http://www.w3schools.com/jsref/jsref_obj_date.asp
Try putting the two values in Date variables and do this:
if(var1.valueOf() > var2.valueOf())
{
//Do Something
}

If your times are always in the format 00:00:00 AM then
var a="06:30:47 AM";
var b="01:10:47 PM";
var at=parseInt(a.substring(0,8).replace(/(^0+|:)/g,""));
var bt=parseInt(b.substring(0,8).replace(/(^0+|:)/g,""));
if (a.charAt(9)=="P") {at=at+120000};
if (b.charAt(9)=="P") {bt=bt+120000};
if (at<bt) {
// a is smaller
}
else
{
// a is not smaller
};
..should be cross-browser and time/format safe.

I tried something like this
var ts1="06:30:47 AM";
var ts2="01:10:47 PM";
var ds=new Date().toDateString();
var d1=new Date(ds+" "+ts1);
var d2=new Date(ds+" "+ts2);
if (!(d2>d1)){
alert("d1 should be less than d2");
}
Is there something wrong with this?

// specific formatter for the time format ##:##:## #M
var formatToMiliseconds = function(t){
t = t.split(/[:\s]/);
t = ((t[0] * 3600000) + (t[1] * 60000) * (t[2] * 1000)); // To ms
t = t + (/PM/i.test(t[3]) ? 43200000 : 0); // adjust for AM/PM
return t;
}
var time01 = formatToMiliseconds('06:30:47 AM');
var time02 = formatToMiliseconds('01:10:47 PM');
alert(time01 > time02); // false
allert(time01 < time02); // true
As a bonus, your time is now more compatible with the Date object and other time calculations.

How can I convert datetime microformat to local time in javascript?

I have a page that is currently using the datetime microformat to display a timestamp, but I have only been showing the human-readable time for my own time zone:
<abbr class="published" title="2009-01-09T09:16:00-05:00">
Friday, January 9, 2009 at 9:16 am (EST)</abbr>
What I'd like to do is rewrite the innerHTML for the abbr tag to be the same format, but in the user's local timezone. So for a reader in Seattle, the above should be converted to:
<abbr class="published" title="2009-01-09T09:16:00-05:00">
Friday, January 9, 2009 at 6:16 am (PST)</abbr>
I've looked at the Javascript Date object, which allows me to get the local timezone offset. But I have a few problems:
I don't see an easy way to create a new Date object from an ISO-8601 timestamp. (I suppose I could parse with substrings or regex if there's no faster way.)
I don't see a way to get the named abbreviation for the timezone. For example, for a reader in Seattle, I'd want the time to have "(PST)" appended to the end, otherwise it is not clear to that user that the timestamp has been converted (especially if he is a frequent visitor and has become accustomed to the fact that my times are in EST).

Here is code of mine that parses an ISO timestamp:
function isoDateStringToDate (datestr) {
if (! this.re) {
// The date in YYYY-MM-DD or YYYYMMDD format
var datere = "(\\d{4})-?(\\d{2})-?(\\d{2})";
// The time in HH:MM:SS[.uuuu] or HHMMSS[.uuuu] format
var timere = "(\\d{2}):?(\\d{2}):?(\\d{2}(?:\\.\\d+)?)";
// The timezone as Z or in +HH[:MM] or -HH[:MM] format
var tzre = "(Z|(?:\\+|-)\\d{2}(?:\\:\\d{2})?)?";
this.re = new RegExp("^" + datere + "[ T]" + timere + tzre + "$");
}
var matches = this.re.exec(datestr);
if (! matches)
return null;
var year = matches[1];
var month = matches[2] - 1;
var day = matches[3];
var hour = matches[4];
var minute = matches[5];
var second = Math.floor(matches[6]);
var ms = matches[6] - second;
var tz = matches[7];
var ms = 0;
var offset = 0;
if (tz && tz != "Z") {
var tzmatches = tz.match(/^(\+|-)(\d{2})(\:(\d{2}))$/);
if (tzmatches) {
offset = Number(tzmatches[2]) * 60 + Number(tzmatches[4]);
if (tzmatches[1] == "-")
offset = -offset;
}
}
offset *= 60 * 1000;
var dateval = Date.UTC(year, month, day, hour, minute, second, ms) - offset;
return new Date(dateval);
}
Unfortunately, it doesn't handle timezone abbreviations either. You would have to modify the "tzre" expression to accept letters, and the only solution I know of to deal with timezone abbreviations in Javascript is to have a look-up table which you keep up to date manually in the event of changes to regional daylight savings times.

EcmaScript formalized the addition of an ISO-8601 style string as an imput for a JavaScript date. Since most JS implementations don't support this, I created a wrapper to the Date object, that has this functionality. If you set the title tags to output in UTC/GMT/Z/Zulu offset, you can use my EcmaScript 5 extensions for JS's Date object.
For DateTime values that are to be used in client-side scripts, I generally try to always do the following. Store date+time in UTC zone (even in databases). Transmit date-times in UTC zone. From client to server, you can use the .toISOString() method in the above link. From server-to client this is relatively easy.
Via jQuery (with extension):
$('.published').each(function(){
var dtm = new Date(this.title);
if (!isNaN(dtm)) {
this.text(dtm.toString());
}
});
I don't recall if I added support for non-utc date-times in the input, but wouldn't be too hard to account for them.