How to add File Upload in WooCommerce Checkout Page

add_action( 'woocommerce_after_order_notes', 'wehelpcode_checkout_file_upload' );
function wehelpcode_checkout_file_upload() {
echo 'Application Form (PDF)*';
wc_enqueue_js( "
    $( '#appform' ).change( function() {
    if ( this.files.length ) {
        const file = this.files[0];
        const formData = new FormData();
        formData.append( 'appform', file );
        $.ajax({
            url: wc_checkout_params.ajax_url + '?action=appformupload',
            type: 'POST',
            data: formData,
            contentType: false,
            enctype: 'multipart/form-data',
            processData: false,
            success: function ( response ) {
                $( 'input[name="appform_field"]' ).val( response );
            }
        });
    }
    });
" );
}
add_action( 'wp_ajax_appformupload', 'wehelpcode_appformupload' );
add_action( 'wp_ajax_nopriv_appformupload', 'wehelpcode_appformupload' );
function wehelpcode_appformupload() {
global $wpdb;
$uploads_dir = wp_upload_dir();
if ( isset( $_FILES['appform'] ) ) {
if ( $upload = wp_upload_bits( $_FILES['appform']['name'], 
       null, file_get_contents( $_FILES['appform']['tmp_name'] ) ) ) 
{
echo $upload['url'];
}
}
die;
}
add_action( 'woocommerce_checkout_process', 'wehelpcode_validate_new_checkout_field' );
function wehelpcode_validate_new_checkout_field() {
if ( empty( $_POST['appform_field'] ) ) {
wc_add_notice( 'Please upload your Application Form', 'error' );
}
}
add_action( 'woocommerce_checkout_update_order_meta', 'wehelpcode_save_new_checkout_field' );
function wehelpcode_save_new_checkout_field( $order_id ) {
if ( ! empty( $_POST['appform_field'] ) ) {
update_post_meta( $order_id, '_application', $_POST['appform_field'] );
}
}
add_action( 'woocommerce_admin_order_data_after_billing_address', 
            'wehelpcode_show_new_checkout_field_order', 10, 1 );
function wehelpcode_show_new_checkout_field_order( $order ) {
$order_id = $order->get_id();
if ( get_post_meta( $order_id, '_application', true ) )
echo 'Purchase Order: ' . get_post_meta( $order_id, '_application', true ) . '';
}
add_action( 'woocommerce_email_after_order_table', 'wehelpcode_show_new_checkout_field_emails', 20, 4 );
function wehelpcode_show_new_checkout_field_emails( $order, $sent_to_admin, $plain_text, $email ) {
    if ( $sent_to_admin && get_post_meta( $order->get_id(), '_application', true ) )
echo 'Purchase Order: ' . get_post_meta( order->get_id(), '_application', true ) . '';
}