> For the complete documentation index, see [llms.txt](https://docs.wem.io/platform/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wem.io/platform/tutorials/building-widgets/wemscript/8-types/4-datetime.md).

# 4. Datetime

A `datetime` type represents a single moment in time in a platform-independent format.

```
<?
	var @d: datetime
	@d := Date(1643, 1, 4)
	@d := '1643-01-04'
	@d := '1643-01-04T13:03:34'
?>
```

#### Postback Format

When performing a postback, the WEM runtime expects the `datetime` to be in ISO date format. You can use the `FormatDate()` function with the `Iso8601` constant as the second argument to convert the `datetime` to this format.

| Valid Formats              |
| -------------------------- |
| 2025-12-31                 |
| 2025-12-31 23:59           |
| 2025-12-31 23:59:59        |
| 2025-12-31 23:59:59.999999 |

An optional "T" can be included between the date and time parts, as in "2025-12-31T23:59". Additionally, you can add timezone-specific parts such as "Z", "+2:00", or "-5:00", as in "2025-12-31T23:59-5:00". Be aware that if you include a timezone part, the WEM runtime will convert the time to local time. For example, a `datetime` of "2025-01-01T01:00:00-2:00" will be converted to "2025-01-01T03:00:00". You can test this with the text datetime input field widget below.

#### Text Datetime Input Field Example

```
<? register input @DateTimeProperty ?>
<label>
	Current date: <?= @DateTimeProperty ?>
	<input type="text" name="<?attr OutputId(@DateTimeProperty) ?>" value="<?attr FormatDate(@DateTimeProperty, Iso8601) ?>">
</label>
```

This is straightforward. The only requirement is to convert the `datetime` value of `@DateTimeProperty` into the correct format using `FormatDate(@DateTimeProperty, Iso8601)`.

#### Native Browser Datetime Input Field Example

```
<? register input @DateTimeProperty ?>
<label>
	Select date and time:
	<input type="datetime-local" name="<?attr OutputId(@DateTimeProperty) ?>" value="<?attr FormatDate(@DateTimeProperty, Iso8601) ?>">
</label>
```

This example is almost identical to the text datetime input field example. The only difference is that we set `type="datetime-local"` on the input field. Since the browser adheres to the same datetime specifications, we can again use `FormatDate(@DateTimeProperty, Iso8601)`.

#### Native Browser Date Input Field Example

```
<? register input @DateProperty ?>
<label>
	Select date:
	<input type="date" name="<?attr OutputId(@DateProperty) ?>" value="<?attr FormatDate(@DateProperty, "yyyy-MM-dd") ?>">
</label>
```

Unfortunately, the browser is a bit stricter in this case. Since we do not need to consider time, we set `type="date"` on the input field. However, we cannot use `Iso8601` as the second argument for `FormatDate()`. The reason is that the browser we tested does not accept a value that includes time. For instance, if you have `value="2025-01-01T23:59:59"`, the entire value will be ignored. Fortunately, we can provide our own format in the `FormatDate()` function, as demonstrated in the widget example above: `FormatDate(@DateProperty, "yyyy-MM-dd")`.

#### JavaScript

Using a `datetime` type within a JavaScript context is quite simple. By printing it with the JavaScript encode `<?js`, you will receive a `new Date()` object in return. For example, if we have a `@DateTimeProperty` and we want to log the year from that datetime in JavaScript:

```
<? startupscript ?>
    const d = <?js @DateTimeProperty ?>;
    console.log(d.getFullYear());
<? end ?>
```

This will result in:

```
<? startupscript ?>
    const d = new Date(2025, 2, 24, 16, 56, 37, 42);
    console.log(d.getFullYear());
<? end ?>
```


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