message_lists: Convert module to typescript.

tools/test-js-with-node

@@ -137,7 +137,7 @@ EXEMPT_FILES = make_set(
         "web/src/message_list_hover.js",
         "web/src/message_list_tooltips.js",
         "web/src/message_list_view.js",
-        "web/src/message_lists.js",
+        "web/src/message_lists.ts",
         "web/src/message_live_update.js",
         "web/src/message_notifications.js",
         "web/src/message_scroll.js",

web/src/message_lists.ts

@@ -1,22 +1,45 @@
 import $ from "jquery";
+import assert from "minimalistic-assert";
 
 import * as blueslip from "./blueslip";
 import * as inbox_util from "./inbox_util";
+import type {Message} from "./message_store";
 import * as recent_view_util from "./recent_view_util";
 import * as ui_util from "./ui_util";
 
-export let home;
-export let current;
+// TODO(typescript): Move this to message_list_view when it's
+// converted to typescript.
+type MessageListView = {
+    update_recipient_bar_background_color: () => void;
+    _render_win_start: number;
+    _render_win_end: number;
+};
 
-export function set_current(msg_list) {
+type MessageList = {
+    table_name: string;
+    view: MessageListView;
+    selected_id: () => number;
+    selected_row: () => JQuery;
+    selected_idx: () => number;
+    all_messages: () => Message[];
+    get: (id: number) => Message | undefined;
+    pre_narrow_offset?: number;
+};
+
+export let home: MessageList | undefined;
+export let current: MessageList | undefined;
+
+export function set_current(msg_list: MessageList): void {
     current = msg_list;
 }
 
-export function set_home(msg_list) {
+export function set_home(msg_list: MessageList): void {
     home = msg_list;
 }
 
-export function all_rendered_message_lists() {
+export function all_rendered_message_lists(): MessageList[] {
+    assert(home !== undefined);
+    assert(current !== undefined);
     const rendered_message_lists = [home];
     if (current !== home && !recent_view_util.is_visible()) {
         rendered_message_lists.push(current);
@@ -24,26 +47,28 @@ export function all_rendered_message_lists() {
     return rendered_message_lists;
 }
 
-export function all_current_message_rows() {
+export function all_current_message_rows(): JQuery {
+    assert(current !== undefined);
     return $(`#${CSS.escape(current.table_name)}.message-list .message_row`);
 }
 
-export function update_recipient_bar_background_color() {
+export function update_recipient_bar_background_color(): void {
     for (const msg_list of all_rendered_message_lists()) {
         msg_list.view.update_recipient_bar_background_color();
     }
     inbox_util.update_stream_colors();
 }
 
-export function save_pre_narrow_offset_for_reload() {
+export function save_pre_narrow_offset_for_reload(): void {
+    assert(current !== undefined);
     if (current.selected_id() !== -1) {
         if (current.selected_row().length === 0) {
+            const current_message = current.get(current.selected_id());
             blueslip.debug("narrow.activate missing selected row", {
                 selected_id: current.selected_id(),
                 selected_idx: current.selected_idx(),
-                selected_idx_exact: current
-                    .all_messages()
-                    .indexOf(current.get(current.selected_id())),
+                selected_idx_exact:
+                    current_message && current.all_messages().indexOf(current_message),
                 render_start: current.view._render_win_start,
                 render_end: current.view._render_win_end,
             });
@@ -52,7 +77,7 @@ export function save_pre_narrow_offset_for_reload() {
     }
 }
 
-export function initialize() {
+export function initialize(): void {
     // For users with automatic color scheme, we need to detect change
     // in `prefers-color-scheme` as it changes based on time.
     ui_util.listener_for_preferred_color_scheme_change(update_recipient_bar_background_color);