Extract topic_list.update_count_in_dom().

This creates the new topic_list.js module, and the first
function that we extract is topic_list.update_count_in_dom().

This function needed to be decoupled from some non-topic-list
stuff which was overly complicated.

static/js/stream_list.js

@@ -362,8 +362,7 @@ exports.set_subject_count = function (stream, subject, count) {
         return;
     }
 
-    count_span.removeClass("zero_count");
-    update_count_in_dom(count_span, value_span, count);
+    topic_list.update_count_in_dom(count_span, value_span, count);
 };
 
 

static/js/topic_list.js

@@ -0,0 +1,20 @@
+var topic_list = (function () {
+
+var exports = {};
+
+exports.update_count_in_dom = function (count_span, value_span, count) {
+    if (count === 0) {
+        count_span.hide();
+        value_span.text('');
+    } else {
+        count_span.removeClass("zero_count");
+        count_span.show();
+        value_span.text(count);
+    }
+};
+
+return exports;
+}());
+if (typeof module !== 'undefined') {
+    module.exports = topic_list;
+}

tools/jslint/check-all.js

@@ -29,7 +29,7 @@ var globals =
     + ' avatar feature_flags search_suggestion referral stream_color Dict'
     + ' Filter summary admin stream_data muting WinChan muting_ui Socket channel gear_menu'
     + ' message_flags bot_data loading favicon resize scroll_bar condense floating_recipient_bar'
-    + ' copy_and_paste click_handlers'
+    + ' copy_and_paste click_handlers topic_list'
 
     // colorspace.js
     + ' colorspace'

zproject/settings.py

@@ -760,6 +760,7 @@ JS_SPECS = {
             'js/viewport.js',
             'js/rows.js',
             'js/unread.js',
+            'js/topic_list.js',
             'js/stream_list.js',
             'js/filter.js',
             'js/message_list_view.js',