JavaScript Date Input
There are generally 3 types of JavaScript date input formats:
| Type | Example |
|---|---|
| ISO Date | “2015-03-25” (The International Standard) |
| Short Date | “03/25/2015” |
| Long Date | “Mar 25 2015” or “25 Mar 2015” |
The ISO format follows a strict standard in JavaScript.
The other formats are not so well defined and might be browser specific.
JavaScript Date Output
Independent of input format, JavaScript will (by default) output dates in full text string format:Wed Aug 24 2022 11:33:32 GMT-0700 (Pacific Daylight Time)
JavaScript ISO Dates
ISO 8601 is the international standard for the representation of dates and times.
The ISO 8601 syntax (YYYY-MM-DD) is also the preferred JavaScript date format:
Example (Complete date)
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript ISO Dates</h2>
<p id="demo"></p>
<script>
const d = new Date("2015-03-25");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript ISO Dates
Tue Mar 24 2015 17:00:00 GMT-0700 (Pacific Daylight Time)
ISO Dates (Year and Month)
ISO dates can be written without specifying the day (YYYY-MM):
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript ISO Dates</h2>
<p id="demo"></p>
<script>
const d = new Date("2015-03");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript ISO Dates
Sat Feb 28 2015 16:00:00 GMT-0800 (Pacific Standard Time)
Time zones will vary the result above between February 28 and March 01.
ISO Dates (Only Year)
ISO dates can be written without month and day (YYYY):
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript ISO Dates</h2>
<p id="demo"></p>
<script>
const d = new Date("2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript ISO Dates
Wed Dec 31 2014 16:00:00 GMT-0800 (Pacific Standard Time)
Time zones will vary the result above between December 31 2014 and January 01 2015.
ISO Dates (Date-Time)
ISO dates can be written with added hours, minutes, and seconds (YYYY-MM-DDTHH:MM:SSZ):
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript ISO Dates</h2>
<p>Separate date and time with a capital T.</p>
<p>Indicate UTC time with a capital Z.</p>
<p id="demo"></p>
<script>
const d = new Date("2015-03-25T12:00:00Z");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript ISO Dates
Separate date and time with a capital T.
Indicate UTC time with a capital Z.
Wed Mar 25 2015 05:00:00 GMT-0700 (Pacific Daylight Time)
Date and time is separated with a capital T.
UTC time is defined with a capital letter Z.
If you want to modify the time relative to UTC, remove the Z and add +HH:MM or -HH:MM instead:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript ISO Dates</h2>
<p>Modify the time relative to UTC by adding +HH:MM or subtraction -HH:MM to the time.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML =
new Date("2015-03-25T12:00:00-06:00");
</script>
</body>
</html>
Result:
JavaScript ISO Dates
Modify the time relative to UTC by adding +HH:MM or subtraction -HH:MM to the time.
Wed Mar 25 2015 11:00:00 GMT-0700 (Pacific Daylight Time)
UTC (Universal Time Coordinated) is the same as GMT (Greenwich Mean Time).
Omitting T or Z in a date-time string can give different results in different browsers.
Time Zones
When setting a date, without specifying the time zone, JavaScript will use the browser’s time zone.
When getting a date, without specifying the time zone, the result is converted to the browser’s time zone.
In other words: If a date/time is created in GMT (Greenwich Mean Time), the date/time will be converted to CDT (Central US Daylight Time) if a user browses from central US.
JavaScript Short Dates.
Short dates are written with an “MM/DD/YYYY” syntax like this:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("03/25/2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Wed Mar 25 2015 00:00:00 GMT-0700 (Pacific Daylight Time)
WARNINGS !
In some browsers, months or days with no leading zeroes may produce an error:
const d = new Date(“2015-3-25”);
The behavior of “YYYY/MM/DD” is undefined.
Some browsers will try to guess the format. Some will return NaN.
const d = new Date(“2015/03/25”);
The behavior of “DD-MM-YYYY” is also undefined.
Some browsers will try to guess the format. Some will return NaN.
const d = new Date(“25-03-2015”);
JavaScript Long Dates.
Long dates are most often written with a “MMM DD YYYY” syntax like this:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("Mar 25 2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Wed Mar 25 2015 00:00:00 GMT-0700 (Pacific Daylight Time)
Month and day can be in any order:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("25 Mar 2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Wed Mar 25 2015 00:00:00 GMT-0700 (Pacific Daylight Time)
And, month can be written in full (January), or abbreviated (Jan):
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("January 25 2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Sun Jan 25 2015 00:00:00 GMT-0800 (Pacific Standard Time)
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("Jan 25 2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Sun Jan 25 2015 00:00:00 GMT-0800 (Pacific Standard Time)
Commas are ignored. Names are case insensitive:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript new Date()</h2>
<p id="demo"></p>
<script>
const d = new Date("JANUARY, 25, 2015");
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript new Date()
Sun Jan 25 2015 00:00:00 GMT-0800 (Pacific Standard Time)
Date Input – Parsing Dates
If you have a valid date string, you can use the Date.parse() method to convert it to milliseconds.
Date.parse() returns the number of milliseconds between the date and January 1, 1970:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Date.parse()</h2>
<p>Date.parse() returns the number of milliseconds between the date and January 1, 1970:</p>
<p id="demo"></p>
<script>
const msec = Date.parse("March 21, 2012");
document.getElementById("demo").innerHTML = msec;
</script>
</body>
</html>
Result:
JavaScript Date.parse()
Date.parse() returns the number of milliseconds between the date and January 1, 1970:
1332313200000
You can then use the number of milliseconds to convert it to a date object:
Example
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Date.parse()</h2>
<p>Date.parse(string) returns milliseconds.</p>
<p>You can use the return value to convert the string to a date object:</p>
<p id="demo"></p>
<script>
let msec = Date.parse("March 21, 2012");
const d = new Date(msec);
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>
Result:
JavaScript Date.parse()
Date.parse(string) returns milliseconds.
You can use the return value to convert the string to a date object:
Wed Mar 21 2012 00:00:00 GMT-0700 (Pacific Daylight Time)