Date

The Date constructor can be used with several types of input:

• You can pass values for year, month, date of the month, hour, minute, second, and millisecond, like so:

          > new Date(2015, 0, 1, 13, 30, 35, 505); 
          Thu Jan 01 2015 13:30:35 GMT-0800 (PST) 
  

• You can skip any of the input parameters, in which case they are assumed to be 0. Note that month values are from 0 (January) to 11 (December), hours are from 0 to 23, minutes and seconds 0 to 59, and milliseconds 0 to 999.

• You can pass a timestamp:

          > new Date(1420147835505); 
          Thu Jan 01 2015 13:30:35 GMT-0800 (PST) 
  

• If you don't pass anything, the current date/time is assumed:

          > new Date(); 
          Fri Jan 11 2013 12:20:45 GMT-0800 (PST) 
  

• If you pass a string, it's parsed in an attempt to extract a possible date value:

          > new Date('May 4, 2015'); 
          Mon May 04 2015 00:00:00 GMT-0700 (PDT) 
  

Omitting new gives you a string version of the current date:

    > Date() === new Date().toString(); 
    true 

Members of the Date constructor

Following are the members of the Date constructor:

Property/method	Description
Date.parse(string)	Similar to passing a string to new Date() constructor, this method parses the input string in attempt to extract a valid date value. Returns a timestamp on success, NaN on failure: > Date.parse('May 5, 2015'); 1430809200000 > Date.parse('4th'); NaN
Date.UTC(year, month, date, hours, minutes, seconds, ms)	Returns a timestamp but in UTC (Coordinated Universal Time), not in local time. > Date.UTC (2015, 0, 1, 13, 30, 35, 505); 1420119035505

The Date.prototype members

Following are the list of Date.prototype members:

Property/method	Description/example
toUTCString()	Same as toString() but in universal time. Here's how Pacific Standard (PST) local time differs from UTC: > var d = new Date(2015, 0, 1); > d.toString(); "Thu Jan 01 2015 00:00:00 GMT-0800 (PST)" > d.toUTCString(); "Thu, 01 Jan 2015 08:00:00 GMT"
toDateString()	Returns only the date portion of toString(): > new Date(2015, 0, 1).toDateString(); "Thu Jan 01 2010"
toTimeString()	Returns only the time portion of toString(): > new Date(2015, 0, 1).toTimeString(); "00:00:00 GMT-0800 (PST)"
toLocaleString() toLocaleDateString() toLocaleTimeString()	Equivalent to toString(), toDateString(), and toTimeString() respectively, but in a friendlier format, according to the current user's locale: > new Date(2015, 0, 1).toString(); "Thu Jan 01 2015 00:00:00 GMT-0800 (PST)" > new Date(2015, 0, 1).toLocaleString(); "1/1/2015 12:00:00 AM"
getTime() setTime(time)	Get or set the time (using a timestamp) of a date object. The following example creates a date and moves it one day forward: > var d = new Date(2015, 0, 1); > d.getTime(); 1420099200000 > d.setTime(d.getTime() + 1000 * 60 * 60 * 24); 1420185600000 > d.toLocaleString(); "Fri Jan 02 2015 00:00:00 GMT-0800 (PST)"
getFullYear() getUTCFullYear() setFullYear(year, month, date) setUTCFullYear(year, month, date)	Get or set a full year using local or UTC time. There is also getYear() but it is not Y2K compliant, so use getFullYear() instead: > var d = new Date(2015, 0, 1); > d.getYear(); 115 > d.getFullYear(); 2015 > d.setFullYear(2020); 1577865600000 > d; Wed Jan 01 2020 00:00:00 GMT-0800 (PST)
getMonth() getUTCMonth() setMonth(month, date) setUTCMonth(month, date)	Get or set month, starting from 0 (January): > var d = new Date(2015, 0, 1); > d.getMonth(); 0 > d.setMonth(11); 1448956800000 > d.toLocaleDateString(); "12/1/2015"
getDate() getUTCDate() setDate(date) setUTCDate(date)	Get or set date of the month. > var d = new Date(2015, 0, 1); > d.toLocaleDateString(); "1/1/2015" > d.getDate(); 1 > d.setDate(31); 1422691200000 > d.toLocaleDateString(); "1/31/2015"
getHours() getUTCHours() setHours(hour, min, sec, ms) setUTCHours(hour, min, sec, ms) getMinutes() getUTCMinutes() setMinutes(min, sec, ms) setUTCMinutes(min, sec, ms) getSeconds() getUTCSeconds() setSeconds(sec, ms) setUTCSeconds(sec, ms) getMilliseconds() getUTCMilliseconds() setMilliseconds(ms) setUTCMilliseconds(ms)	Get/Set hour, minutes, seconds, milliseconds, all starting from 0: > var d = new Date(2015, 0, 1); > d.getHours() + ':' + d.getMinutes(); "0:0" > d.setMinutes(59); 1420102740000 > d.getHours() + ':' + d.getMinutes(); "0:59"
getTimezoneOffset()	Returns the difference between local and universal (UTC) time, measured in minutes. For example the difference between PST (Pacific Standard Time) and UTC: > new Date().getTimezoneOffset(); 480 > 420 / 60; // hours 8
getDay() getUTCDay()	Returns the day of the week, starting from 0 (Sunday): > var d = new Date(2015, 0, 1); > d.toDateString(); "Thu Jan 01 2015" > d.getDay(); 4 > var d = new Date(2015, 0, 4); > d.toDateString(); "Sat Jan 04 2015" > d.getDay(); 0

ECMAScript 5 additions to Date

Following are the additions to the Date constructor:

Property/method	Description
Date.now()	A convenient way to get the current timestamp: > Date.now() === new Date().getTime(); true
Date.prototype.toISOString()	Yet another toString(): > var d = new Date(2015, 0, 1); > d.toString(); "Thu Jan 01 2015 00:00:00 GMT-0800 (PST)" > d.toUTCString(); "Thu, 01 Jan 2015 08:00:00 GMT" > d.toISOString(); "2015-01-01T00:00:00.000Z"
Date.prototype.toJSON()	Used by JSON.stringify() (refer to the end of this appendix) and returns the same as toISOString(): > var d = new Date(); > d.toJSON() === d.toISOString(); true