How to Set Value of HTML "date" input Element Using PHP?

The HTML <input type="date"> element expects the value attribute to be set in "YYYY-MM-DD" format. Therefore, if you're setting a default value to it using PHP, then you must adhere to the correct date format (i.e. "Y-m-d" in PHP).

For example, you can set the current date using DateTime (or DateTimeImmutable), in the following way:

$dt = new DateTime();

echo '<input type="date" value="' . $dt->format('Y-m-d') . '" />';

Similarly, you can set a specific date using DateTime (or DateTimeImmutable), in the following way:

$dt = new DateTime('16.10.2022');

echo '<input type="date" value="' . $dt->format('Y-m-d') . '" />';

There are several other ways in which you can create a formatted date in PHP. For example, you may use the date_create() function as an alternative, which creates a new DateTime object:

$dt = date_create('16.10.2022');

echo '<input type="date" value="' . $dt->format('Y-m-d') . '" />';