ajax latest posts ( http://stackoverflow.com/questions/17738638/concatenate-arrays-from-foreach-loop-into-single-variable-of-nested-arrays )

gistfile1.php

function ajax_get_latest_posts(){   
   $attachments = get_children(array('post_parent' => $post->ID,
                    'post_status' => 'inherit',
                    'post_type' => 'attachment',
                    'post_mime_type' => 'image',
                    'order' => 'ASC',
                    'orderby' => 'menu_order ID'));

   $allimagesizes = array();
   foreach($attachments as $att_id => $attachment) {
      $large_bg_url = wp_get_attachment_image_src($attachment->ID, 'background-large');
      $medium_bg_url = wp_get_attachment_image_src($attachment->ID, 'background-medium');
      $small_bg_url = wp_get_attachment_image_src($attachment->ID, 'background-small');
      $imagesizes = array('background_large' => $large_bg_url[0], 'background_medium' => $medium_bg_url[0], 'background_small' => $small_bg_url[0]);
      $allimagesizes[] = $imagesizes;
   }
   return $allimagesizes;
}