<?php
 $args = array( 'post_type' => 'product', 'posts_per_page' => 200, 'product_cat' => 'books');
       $loop = new WP_Query( $args );


    $send_array = array();
       while ( $loop->have_posts() ) : $loop->the_post();
        global $product;

    $send_array[] = array(

        'id' => get_the_ID(),
        'title' => get_the_title(),
        'content' => get_the_content(),
        'regular_price' => get_post_meta( get_the_ID(), '_regular_price', true),
        'sale_price'=> get_post_meta( get_the_ID(), '_sale_price', true),
        'weight' => woocommerce_get_product_terms($product->id, 'weight', 'names')

    );

     endwhile;

     wp_reset_query();
        ob_clean();
        echo json_encode($send_array);
        exit();

    ?>

$weight = woocommerce_get_product_terms($product->id, 'pa_weight', 'names');

$send_array[] = array(

    'id' => get_the_ID(),
    'title' => get_the_title(),
    'content' => get_the_content(),
    'regular_price' => get_post_meta( get_the_ID(), '_regular_price', true),
    'sale_price'=> get_post_meta( get_the_ID(), '_sale_price', true),
    'weight' => $weight[0]

);

$item_weight=wp_get_post_terms($post->ID, 'pa_weight', array("fields" => "names"));

$send_array[] = array(

    'id' => get_the_ID(),
    'title' => get_the_title(),
    'content' => get_the_content(),
    'regular_price' => get_post_meta( get_the_ID(), '_regular_price', true),
    'sale_price'=> get_post_meta( get_the_ID(), '_sale_price', true),
    'weight' => $item_weight[0]

);

$items = WC()->cart->get_cart();
           $x = 0;
        foreach($items as $item => $values) {
            $_product2 = $values['data'];

            $getProductDetail = wc_get_product( $values['product_id'] );

               echo $getProductDetail->get_image(); // accepts 2 arguments ( size,      attr )


              $weight = $getProductDetail->product_attributes;
                 echo 'Weight: '.$weight["weight"]["value"].'<br>';

                    }