JavaScript - New Date

JavaScript dates are calculated in milliseconds from 01 January, 1970 00:00:00 Universal Time (UTC). One day contains 86,400,000 millisecond. The Date object lets us work with dates. A date consists of a year, a month, a day, an hour, a minute, a second, and milliseconds.

// static method
document.getElementById("demo").innerHTML = Date();

Date objects are created with the new Date() constructor. There are 4 ways of initiating a date:

• new Date();
• new Date(milliseconds);
• new Date(dateString);
• new Date(year, month, day, hours, minutes, seconds, milliseconds);

new Date()
Using new Date(), creates a new date object with the current date and time.

// var d = new Date();
// document.write(d);
Thu Nov 30 2017 07:22:49 GMT-0500 (Eastern Standard Time)

new Date([string])
Using new Date(date string), creates a new date object from the specified date and time.

var d = new Date("October 13, 2014 11:13:00");
document.getElementById("demo").innerHTML = d;
Mon Oct 13 2014 11:13:00 GMT-0400 (Eastern Daylight Time)

new Date([number])
Using new Date(number), creates a new date object as zero time plus the number. Zero time is 01 January 1970 00:00:00 UTC. The number is specified in milliseconds:

    
var d = new Date(86400000);
document.getElementById("demo").innerHTML = d;
Thu Jan 01 1970 19:00:00 GMT-0500 (Eastern Standard Time)
        
        

new Date([7 numbers])
Using new Date(7 numbers), creates a new date object with the specified date and time. The 7 numbers specify the year, month, day, hour, minute, second, and millisecond, in that order. Only the first 3 are required.

// year, month, day, hour (optional), minute (optional), second (optional), millisecond (optional)
var d = new Date(99,5,24,11,33,30,0);
document.getElementById("demo").innerHTML = d;