WordPress img srcset

wpimgsrcset

<?php
    $id = get_post_thumbnail_id();
    $size = 'medium';
    $img_src = wp_get_attachment_image_url( $id, $size );
    $img_srcset = wp_get_attachment_image_srcset( $id, $size );
    $title = get_post($id)->post_title;
    $alt = get_post_meta($id, '_wp_attachment_image_alt')[0];
?>
<img src="<?php echo esc_url( $img_src ); ?>"
     srcset="<?php echo esc_attr( $img_srcset ); ?>"
     sizes="(min-width: 768px) 500px, 100vw" 
     alt="<?php echo $alt; ?>"
     title="<?php echo $title; ?>"
     class="feature">