js: add get_feed_unread()

feedlist.js

@@ -149,11 +149,10 @@ function viewfeed(feed, subop, is_cat, subop_param, skip_history, offset) {
 				queue: { position:'end', scope: 'FEEDL-' + feed, limit: 1 } } );
 		}
 
-		var unread_ctr = document.getElementById("FEEDU-" + feed);
+		var unread_ctr = get_feed_unread(feed);
 		var cache_check = false;
 
-		if (unread_ctr && !page_offset && !force_nocache && !subop) {
-			unread_ctr = unread_ctr.innerHTML;
+		if (unread_ctr != -1 && !page_offset && !force_nocache && !subop) {
 
 			var cache_prefix = "";
 				

functions.js

@@ -778,6 +778,15 @@ function all_counters_callback2(transport) {
 	}
 }
 
+function get_feed_unread(id) {
+	try {
+		return parseInt(document.getElementById("FEEDU-" + id).innerHTML);	
+	} catch (e) {
+		exception_error("get_feed_unread", e, true);
+		return -1;
+	}
+}
+
 function get_feed_entry_unread(doc, elem) {
 
 	var id = elem.id.replace("FEEDR-", "");