diff --git a/static/js/channel.js b/static/js/channel.js
index 50fee79743..60bed8f69f 100644
--- a/static/js/channel.js
+++ b/static/js/channel.js
@@ -9,7 +9,7 @@ function add_pending_request(jqXHR) {
 }
 
 function remove_pending_request(jqXHR) {
-    const pending_request_index = _.indexOf(pending_requests, jqXHR);
+    const pending_request_index = pending_requests.indexOf(jqXHR);
     if (pending_request_index !== -1) {
         pending_requests.splice(pending_request_index, 1);
     }
diff --git a/static/js/message_events.js b/static/js/message_events.js
index 68c94bc272..a14b68c5de 100644
--- a/static/js/message_events.js
+++ b/static/js/message_events.js
@@ -142,7 +142,7 @@ exports.update_messages = function update_messages(events) {
             // where the user initiated the edit.
             topic_edited = true;
 
-            const going_forward_change = _.indexOf(['change_later', 'change_all'], event.propagate_mode) >= 0;
+            const going_forward_change = ['change_later', 'change_all'].indexOf(event.propagate_mode) >= 0;
 
             const stream_name = stream_data.get_sub_by_id(event.stream_id).name;
             const compose_stream_name = compose_state.stream_name();
@@ -161,7 +161,7 @@ exports.update_messages = function update_messages(events) {
             const current_filter = narrow_state.filter();
             if (going_forward_change) {
                 const current_id = current_msg_list.selected_id();
-                const selection_changed_topic = _.indexOf(event.message_ids, current_id) >= 0;
+                const selection_changed_topic = event.message_ids.indexOf(current_id) >= 0;
                 if (selection_changed_topic) {
                     if (current_filter && stream_name) {
                         if (current_filter.has_topic(stream_name, orig_topic)) {
diff --git a/static/js/topic_generator.js b/static/js/topic_generator.js
index 0ef93dfc79..4ceace1cf6 100644
--- a/static/js/topic_generator.js
+++ b/static/js/topic_generator.js
@@ -80,7 +80,7 @@ exports.wrap = function (lst, val) {
         return exports.list_generator(lst);
     }
 
-    const i = _.indexOf(lst, val);
+    const i = lst.indexOf(val);
     if (i < 0) {
         return exports.list_generator(lst);
     }
@@ -98,7 +98,7 @@ exports.wrap_exclude = function (lst, val) {
         return exports.list_generator(lst);
     }
 
-    const i = _.indexOf(lst, val);
+    const i = lst.indexOf(val);
     if (i < 0) {
         return exports.list_generator(lst);
     }
@@ -116,7 +116,7 @@ exports.reverse_wrap_exclude = function (lst, val) {
         return exports.reverse_list_generator(lst);
     }
 
-    const i = _.indexOf(lst, val);
+    const i = lst.indexOf(val);
     if (i < 0) {
         return exports.reverse_list_generator(lst);
     }
diff --git a/static/js/upload_widget.js b/static/js/upload_widget.js
index f315856703..a082eaca3e 100644
--- a/static/js/upload_widget.js
+++ b/static/js/upload_widget.js
@@ -12,7 +12,7 @@ function is_image_format(file) {
     if (!type) {
         return false;
     }
-    return _.indexOf(supported_types, type) >= 0;
+    return supported_types.indexOf(type) >= 0;
 }
 
 exports.build_widget = function (