PHP uses iframe to implement code for uploading files without refreshing_PHP tutorial

　
　
　php code
　　sleep(2);
　$fileTypes = array('jpg','png','gif','bmp') ;
$result = null;
$uploadDir = './upfiles';
$maxSize = 1 * pow(2,20);
if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['sub'])) {
$myfile = $_FILES['myfile'];
$myfileType = substr($myfile['name'], strrpos($myfile ['name'], ".") + 1);
if ($myfile['size'] > $maxSize) {
$result = 1;
} else if (!in_array( $myfileType, $fileTypes)) {
$result = 2;
} elseif (is_uploaded_file($myfile['tmp_name'])) {
$toFile = $uploadDir . '/' . $myfile[ 'name'];
if (@move_uploaded_file($myfile['tmp_name'], $toFile)) {
$result = 0;
} else {
$result = -1;
　}
　} else {
　$result = 1;
　}
　}
　?>