I wrote some code to upload multiple files to a server with PHP and JavaScript. I'm happy with the form and JavaScript, below.

<form method="post" enctype="multipart/form-data">
    <input type="file" name="files[]" multiple>
    <input type="submit" value="Upload File" name="submit">
</form>

<script>
    const url = 'process.php';
    const submit = document.querySelector('[type=submit]');

    submit.addEventListener('click', e => {
        e.preventDefault();

        const files = document.querySelector('[type=file]').files;
        const formData = new FormData();

        for (let i = 0; i < files.length; i++) {
            let file = files[i];

            formData.append('files[]', file);
        }

        fetch(url, {
            method: 'POST',
            body: formData
        }).then(response => {
            console.log(response);
        });
    });
</script>

I would appreciate a review of the PHP for handling the $_POST request. I tried to make it as simple as possible, but I'm not sure if there are any major security concerns I'm overlooking. Thanks!

<?php 
if ($_SERVER["REQUEST_METHOD"] === 'POST') {
    if (isset($_FILES['files'])) {
        $errors = [];
        $path = 'uploads/';
        $extensions = ['jpg', 'jpeg', 'png', 'gif', 'html', 'txt', 'pdf', 'doc'];

        $allFiles = count($_FILES['files']['tmp_name']);
        
        for ($i = 0; $i < $allFiles; $i++) {  
            try {
                $file_name = $_FILES['files']['name'][$i];
                $file_tmp = $_FILES['files']['tmp_name'][$i];
                $file_type = $_FILES['files']['type'][$i];
                $file_ext = strtolower(end(explode('.', $_FILES['files']['name'][$i])));

                $file = $path . $file_name;
                
                if (!in_array($file_ext, $extensions)) {
                    throw new Exception('Extension not allowed: ' . $file_name . ' ' . $file_type . "\n");
                }

                if ($file_size > 2097152) {
                    // 2MB
                    throw new Exception('File size exceeds limit: ' . $file_name . ' ' . $file_type. "\n");
                }
                move_uploaded_file($file_tmp, $file);
            } catch (Exception $e) {
                error_log($e->getMessage(), 3, '/path/to/error_log');
            }
        }
    }
}