Display Button Variable Products WooCommerce

functions.php

add_action( 'woocommerce_before_add_to_cart_button' , 'woocommerce_before_add_to_cart_button_variation' );
function woocommerce_before_add_to_cart_button_variation() {
    global $woocommerce, $product, $post;

    if ( empty( $available_variations )) {
        echo '<button id="newbutton" type="submit" class="single_add_to_cart_button button alt">' . $product->single_add_to_cart_text() . '</button>';
    } 
}

add_action( 'woocommerce_after_add_to_cart_form' , 'woocommerce_after_add_to_cart_form_remove_button', 1000 );
function woocommerce_after_add_to_cart_form_remove_button() {
    echo "<Script>";
    echo "var myBTN = document.getElementById('monitorthisspace');";
    echo "myBTN.addEventListener('click', function() {";
    echo "document.getElementById('newbutton').style.display = 'none';";
    echo "}, false);";
    echo "</Script>";
 }