popover: Extract with_first_message_id helper.

static/js/stream_popover.js

@@ -548,6 +548,43 @@ export function register_stream_handlers() {
     });
 }
 
+function with_first_message_id(stream_id, topic_name, success_cb, error_cb) {
+    // The API endpoint for editing messages to change their
+    // content, topic, or stream requires a message ID.
+    //
+    // Because we don't have full data in the browser client, it's
+    // possible that we might display a topic in the left sidebar
+    // (and thus expose the UI for moving its topic to another
+    // stream) without having a message ID that is definitely
+    // within the topic.  (The comments in stream_topic_history.js
+    // discuss the tricky issues around message deletion that are
+    // involved here).
+    //
+    // To ensure this option works reliably at a small latency
+    // cost for a rare operation, we just ask the server for the
+    // latest message ID in the topic.
+    const data = {
+        anchor: "newest",
+        num_before: 1,
+        num_after: 0,
+        narrow: JSON.stringify([
+            {operator: "stream", operand: stream_id},
+            {operator: "topic", operand: topic_name},
+        ]),
+    };
+
+    channel.get({
+        url: "/json/messages",
+        data,
+        idempotent: true,
+        success(data) {
+            const message_id = data.messages[0].id;
+            success_cb(message_id);
+        },
+        error_cb,
+    });
+}
+
 export function register_topic_handlers() {
     // Mute the topic
     $("body").on("click", ".sidebar-popover-mute-topic", (e) => {
@@ -668,38 +705,11 @@ export function register_topic_handlers() {
             return;
         }
 
-        // The API endpoint for editing messages to change their
-        // content, topic, or stream requires a message ID.
-        //
-        // Because we don't have full data in the browser client, it's
-        // possible that we might display a topic in the left sidebar
-        // (and thus expose the UI for moving its topic to another
-        // stream) without having a message ID that is definitely
-        // within the topic.  (The comments in stream_topic_history.js
-        // discuss the tricky issues around message deletion that are
-        // involved here).
-        //
-        // To ensure this option works reliably at a small latency
-        // cost for a rare operation, we just ask the server for the
-        // latest message ID in the topic.
-        const data = {
-            anchor: "newest",
-            num_before: 1,
-            num_after: 0,
-            narrow: JSON.stringify([
-                {operator: "stream", operand: current_stream_id},
-                {operator: "topic", operand: old_topic_name},
-            ]),
-        };
-
         message_edit.show_topic_move_spinner();
-        channel.get({
+        with_first_message_id(
-            url: "/json/messages",
+            current_stream_id,
-            data,
+            old_topic_name,
-            idempotent: true,
+            (message_id) => {
-            success(data) {
-                const message_id = data.messages[0].id;
-
                 if (old_topic_name.trim() === new_topic_name.trim()) {
                     // We use `undefined` to tell the server that
                     // there has been no change in the topic name.
@@ -716,10 +726,10 @@ export function register_topic_handlers() {
                     );
                 }
             },
-            error(xhr) {
+            (xhr) => {
                 message_edit.hide_topic_move_spinner();
                 show_error_msg(xhr.responseJSON.msg);
             },
-        });
+        );
     });
 }