Uploading files in PHP

upload.php

<?php
//Here is our upload script resides
//Check whether the form really submits
if($_SERVER["REQUEST_METHOD"] == "POST"){
    if(!empty($_FILES['image']['name'])) {
        $uploadDir = './uploads/';
        $uploadFilename = $uploadDir.basename($_FILES['image']['name']);

        //Check extension
        $ext = pathinfo($filename, PATHINFO_EXTENSION);
        if(!in_array($ext,array('jpg','png'))) {
            echo "Oops. Invalid file type";
            exit;
        }

        if (move_uploaded_file($_FILES['file']['tmp_name'], $uploadFile)) {
            echo "File Uploaded successfully!";
        }
        else {
            echo "Oops!. something went wrong!";
        }

    }
}