From de347e1f81c68d3e833c83e7a906fe80a4af28df Mon Sep 17 00:00:00 2001
From: Stefan Kalscheuer <stefan@stklcode.de>
Date: Sat, 9 Dec 2017 11:48:23 +0100
Subject: [PATCH] Only send new Ticks on AJAX update

THis reduces the overhead of re-sending huge amounts of HTML code to the frontend without any new data to display.
---
 includes/class-wpliveticker2.php | 12 ++++++++----
 scripts/wp-liveticker2.js        | 11 ++++++++---
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/includes/class-wpliveticker2.php b/includes/class-wpliveticker2.php
index 2b29115..1f56ef3 100644
--- a/includes/class-wpliveticker2.php
+++ b/includes/class-wpliveticker2.php
@@ -179,8 +179,9 @@ class WPLiveticker2 {
 			$output = '<ul class="wplt2-ticker';
 			if ( 1 === self::$_options['enable_ajax'] ) {
 				$output .= ' wplt2-ticker-ajax" '
-						. 'data-wplt2-ticker="' . $atts['ticker'] . '" '
-						. 'data-wplt2-limit="' . $atts['limit'];
+							. 'data-wplt2-ticker="' . $atts['ticker'] . '" '
+							. 'data-wplt2-limit="' . $atts['limit'] . '" '
+							. 'data-wplt2-last="' . time();
 			}
 			$output .= '">';
 
@@ -266,8 +267,8 @@ class WPLiveticker2 {
 			$res = array();
 			foreach ( wp_unslash( $_POST['update'] ) as $update_req ) {
 				if ( isset( $update_req['s'] ) ) {
-					$slug     = $update_req['s'];
-					$limit    = ( isset( $update_req['l'] ) ) ? intval( $update_req['l'] ) : - 1;
+					$slug      = $update_req['s'];
+					$limit     = ( isset( $update_req['l'] ) ) ? intval( $update_req['l'] ) : - 1;
 					$last_poll = ( isset( $update_req['t'] ) ) ? intval( $update_req['t'] ) : 0;
 
 					// Query new ticks from DB.
@@ -281,6 +282,9 @@ class WPLiveticker2 {
 								'terms'    => $slug,
 							),
 						),
+						'date_query'     => array(
+							'after' => date( 'c', $last_poll ),
+						)
 					);
 
 					$query = new WP_Query( $query_args );
diff --git a/scripts/wp-liveticker2.js b/scripts/wp-liveticker2.js
index 42aa6c2..9dee3dd 100644
--- a/scripts/wp-liveticker2.js
+++ b/scripts/wp-liveticker2.js
@@ -42,9 +42,14 @@ WPLT2.update = function () {
 					jQuery.each(update, function (i, u) {
 						jQuery.each(WPLT2.ticker, function (j, t) {
 							if (t.s === u.s) {
-								// Set HTML content.
-								jQuery(t.e).html(u.h);
-								// Set last poll timestamp.
+								// Prepend HTML of new ticks.
+								jQuery(t.e).prepend(u.h);
+								// Remove tail, if limit is set.
+								const l = jQuery(t.e).data('wplt2Limit');
+								if (l > 0) {
+									jQuery(t.e).find('li').slice(l).remove();
+								}
+								// Update last poll timestamp.
 								jQuery(t.e).data('wplt2Last', u.t);
 							}
 						});