i do not know how to fix this message that appears on line with $newfilename = uniqid() ... :
$allowedExts = array("gif", "jpeg", "jpg", "png", "zip", "html", "htm", "js", "css", "less", "txt", "php");
$temp = explode(".", $_FILES["file"]["name"]);
$extension = end($temp);
// skipped
echo // here the echo's
$newfilename = uniqid().".".end(explode(".",$_FILES["file"]["name"]));
move_uploaded_file($_FILES["file"]["tmp_name"], "uploads/" . $newfilename);
// het pad naar het bestand dat geupload is; ervan uitgaande dat de map uploads in de root staat
echo 'Url: ' . '<b>http://www.jouwwebsite.nl/uploads/' . $newfilename.'</b>';
echo '<br /><br />';
}
// skipped...