How to save Date objects in different time zones in JavaScript

Question

Is it possible for JavaScript to store Date objects in different time zones, for example:

date1.toString(); >>> 2012-02-16T14:00+02:00 date2.toString(); >>> 2012-03-16T13:00+01:00 

i.e. I have two date objects that reflect the same point in time, but store their information in different time zones.

Answer 1

Not. Dates in JavaScript represent a point in time; they do not store time zone information. Then you can choose to display the time displayed in a specific time zone. (See Various methods, such as getHours() - the current local time zone - compared to getUTCHours() .)

To display the time in a time zone other than UTC or local, you need to write (or use) a function that does a bit of math:

 function offsetDate( date, hours ){ return date.setUTCHours( date.getUTCHours() + hours ); } 

Change You can save an arbitrary offset along with the date (since you can add custom properties to any JS object):

 Date.prototype.withZone = function(){ var o = new Date(this.getTime()); // Make a copy for mutating o.setUTCHours(o.getUTCHours() + (this.tz || 0)); // Move the UTC time // Return a custom formatted version of the date var offset = this.tz ? (this.tz<0 ? this.tz : ('+'+this.tz)) : 'Z'; return o.customFormat('#YYYY#-#MMM#-#D# @ #h#:#mm##ampm# ('+offset+')'); } // http://phrogz.net/JS/FormatDateTime_js.txt Date.prototype.customFormat = function(formatString){ var YYYY,YY,MMMM,MMM,MM,M,DDDD,DDD,DD,D,hhh,hh,h,mm,m,ss,s,ampm,AMPM,dMod,th; YY = ((YYYY=this.getUTCFullYear())+"").slice(-2); MM = (M=this.getUTCMonth()+1)<10?('0'+M):M; MMM = (MMMM=["January","February","March","April","May","June","July","August","September","October","November","December"][M-1]).substring(0,3); DD = (D=this.getUTCDate())<10?('0'+D):D; DDD = (DDDD=["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"][this.getUTCDay()]).substring(0,3); th=(D>=10&&D<=20)?'th':((dMod=D%10)==1)?'st':(dMod==2)?'nd':(dMod==3)?'rd':'th'; formatString = formatString.replace("#YYYY#",YYYY).replace("#YY#",YY).replace("#MMMM#",MMMM).replace("#MMM#",MMM).replace("#MM#",MM).replace("#M#",M).replace("#DDDD#",DDDD).replace("#DDD#",DDD).replace("#DD#",DD).replace("#D#",D).replace("#th#",th); h=(hhh=this.getUTCHours()); if (h==0) h=24; if (h>12) h-=12; hh = h<10?('0'+h):h; AMPM=(ampm=hhh<12?'am':'pm').toUpperCase(); mm=(m=this.getUTCMinutes())<10?('0'+m):m; ss=(s=this.getUTCSeconds())<10?('0'+s):s; return formatString.replace("#hhh#",hhh).replace("#hh#",hh).replace("#h#",h).replace("#mm#",mm).replace("#m#",m).replace("#ss#",ss).replace("#s#",s).replace("#ampm#",ampm).replace("#AMPM#",AMPM); } var now = new Date; // Make a plain date console.log( now.withZone() ); //-> 2012-Feb-16 @ 9:37pm (Z) now.tz = -7; // Add a custom property for our method to use console.log( now.withZone() ); //-> 2012-Feb-16 @ 2:37pm (-7) 

Answer 2

As far as I can tell, you cannot install it, but you can get it: Here is the link: http://www.w3schools.com/jsref/jsref_gettimezoneoffset.asp

 var d = new Date() var gmtHours = -d.getTimezoneOffset()/60; document.write("The local time zone is: GMT " + gmtHours); 

Answer 3

Most browsers support toISOString (). Converting back to date is not supported by afaik. Here you can find a working solution here for cross-browser support.