- json_encode: documentation ( source)
<?php
$now = new DateTime();
echo json_encode($now->format(\DateTime::ISO8601));
$new = new DateTime('2016-01-12T10:25:29+0100');
echo $new->__toString();
echo json_encode(new DateTime('@1419237113'));
$datetime = new DateTime('2014-12-22 08:31:53');
echo $datetime->__toString();