stream_settings: Fix stream row switching behavior.

Add a rule to the switch_rows(event) function to avoid
switching stream row when pressing up/down key by checking
the current URL hash and the add_subscribers_pill focus state.
Add a utility function to hash_parser to help implement new
switch_rows behavior mentioned above.

Fixes #29690

web/src/hash_parser.ts

@@ -91,6 +91,20 @@ export function is_create_new_stream_narrow(): boolean {
     return window.location.hash === "#streams/new";
 }
 
+// this checks whether the use is in the stream settings and in the
+// 'Subscribers' tab on the right panel of stream settings
+export function is_editing_stream_subscribers(): boolean {
+    const hash_components = window.location.hash.slice(1).split(/\//);
+
+    if (hash_components[0] !== "streams") {
+        return false;
+    }
+    if (!hash_components[3]) {
+        return false;
+    }
+    return hash_components[3] === "subscribers"
+}
+
 export const allowed_web_public_narrows = [
     "channels",
     "channel",

web/src/stream_settings_ui.js

@@ -680,6 +680,7 @@ export function setup_page(callback) {
         // streams, either explicitly via user_can_create_streams, or
         // implicitly because realm.realm_is_zephyr_mirror_realm.
         $("#stream_filter input[type='text']").on("keypress", (e) => {
+
             if (!keydown_util.is_enter_event(e)) {
                 return;
             }
@@ -796,10 +797,15 @@ export function launch(section, left_side_tab, right_side_tab) {
 
 export function switch_rows(event) {
     const active_data = stream_settings_components.get_active_data();
+    let $add_subscriber_pill = $(".add_subscribers_container > div > .input");
     let $switch_row;
+
     if (hash_parser.is_create_new_stream_narrow()) {
         // Prevent switching stream rows when creating a new stream
         return false;
+    } else if (hash_parser.is_editing_stream_subscribers && $add_subscriber_pill.is(":focus")) {
+        // Prevent switching stream rows when adding a subscriber
+        return false;
     } else if (!active_data.id || active_data.$row.hasClass("notdisplayed")) {
         $switch_row = $("div.stream-row:not(.notdisplayed)").first();
         if ($("#search_stream_name").is(":focus")) {