Add a simple search functionality to the catalog

Requires commit 20ce699 which adds a wrapper for the controls on the
catalog page.

js/catalog-search.js

@@ -0,0 +1,45 @@
+/*
+ * catalog-search.js
+ * https://github.com/mgrabovsky/lainchan/lainchan/blob/catalog-search/js/catalog-search.js
+ *
+ * Released under the MIT license
+ * Copyright (c) 2015 Matěj Grabovský <matej.grabovsky@gmail.com>
+ *
+ * Usage:
+ *   $config['additional_javascript'][] = 'js/jquery.min.js';
+ *   $config['additional_javascript'][] = 'js/catalog-search.js';
+ */
+
+(function() {
+
+var catalogSearch = function() {
+	var $controls = $('.controls'),
+		$threads = $('.threads .thread'),
+		$searchLabel = $('<label for="catalog_search">Search: </label>'),
+		$searchBox = $('<input id="catalog_search" type="search" placeholder="Search" />');
+
+	$controls.append($searchLabel)
+			.append($searchBox);
+
+	$searchBox.change(function() {
+		var query = new RegExp(this.value, 'm'),
+			$found = searchThreads($threads, query);
+		$threads.hide();
+		$found.show();
+	});
+};
+
+// Filter threads by their content, given a regex. Can be extended later to load data
+// remotely and filter by multiple fields
+var searchThreads = function($threads, re) {
+	return $threads.filter(function() {
+		return re.test($('.replies', this).text());
+	});
+};
+
+// Only load in the catalog
+if (active_page == 'catalog') {
+	onready(catalogSearch);
+}
+
+}());