JavaScript Dates

The Date object lets you work with dates (years, months, days, hours, minutes, seconds, and milliseconds)

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JavaScript Date Formats

A JavaScript date can be written as a string:
Thu May 07 2015 14:12:12 GMT+0800 (Malay Peninsula Standard Time)
or as a number:
1430979132166
Dates written as numbers, specifies the number of milliseconds since January 1, 1970, 00:00:00.

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Displaying Dates

In this tutorial we use a script to display dates inside a <p> element with id="demo":

Example

<p id="demo"></p>

<script>
document.getElementById("demo").innerHTML = Date();
</script>

 

Creating Date Objects

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.
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)

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

Example

<script>
var d = new Date();
document.getElementById("demo").innerHTML = d;
</script> 

 

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

Example

<script>
var d = new Date("October 13, 2014 11:13:00");
document.getElementById("demo").innerHTML = d;
</script>

 

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:

Example

<script>
var d = new Date(86400000);
document.getElementById("demo").innerHTML = d;
</script> 

 

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:

Example

<script>
var d = new Date(99,5,24,11,33,30,0);
document.getElementById("demo").innerHTML = d;
</script>

 

 Variants of the example above let us omit any of the last 4 parameters:

Example

<script>
var d = new Date(99,5,24);
document.getElementById("demo").innerHTML = d;
</script>

 

Date Methods

When a Date object is created, a number of methods allow you to operate on it.
Date methods allow you to get and set the year, month, day, hour, minute, second, and millisecond of objects, using either local time or UTC (universal, or GMT) time.

	Date methods are covered in a later chapter.

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Displaying Dates

When you display a date object in HTML, it is automatically converted to a string, with the toString() method.

Example

<p id="demo"></p>

<script>
d = new Date();
document.getElementById("demo").innerHTML = d;
</script>

Is the same as:

<p id="demo"></p>

<script>
d = new Date();
document.getElementById("demo").innerHTML = d.toString();
</script> 

 

The toUTCString() method converts a date to a UTC string (a date display standard).

Example

<script>
var d = new Date();
document.getElementById("demo").innerHTML = d.toUTCString();
</script> 

 

The toDateString() method converts a date to a more readable format:

Example

<script>
var d = new Date();
document.getElementById("demo").innerHTML = d.toDateString();
</script>