From fcb212721a1f8898aaa0ff73b3e43c5c1e0e155e Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <anders@zulip.com>
Date: Fri, 22 Sep 2023 01:42:54 -0700
Subject: [PATCH] list_cursor: Convert module to TypeScript.

Signed-off-by: Anders Kaseorg <anders@zulip.com>
---
 web/src/{list_cursor.js => list_cursor.ts} | 45 +++++++++++-----------
 web/src/stream_list.js                     |  4 +-
 web/tests/list_cursor.test.js              |  5 ---
 3 files changed, 24 insertions(+), 30 deletions(-)
 rename web/src/{list_cursor.js => list_cursor.ts} (82%)

diff --git a/web/src/list_cursor.js b/web/src/list_cursor.ts
similarity index 82%
rename from web/src/list_cursor.js
rename to web/src/list_cursor.ts
index cd138a91ae..cff71248d5 100644
--- a/web/src/list_cursor.js
+++ b/web/src/list_cursor.ts
@@ -3,26 +3,25 @@ import $ from "jquery";
 import * as blueslip from "./blueslip";
 import * as scroll_util from "./scroll_util";
 
-export class ListCursor {
-    constructor({highlight_class, list}) {
-        const config_ok =
-            highlight_class &&
-            list &&
-            list.scroll_container_sel &&
-            list.find_li &&
-            list.first_key &&
-            list.prev_key &&
-            list.next_key;
-        if (!config_ok) {
-            blueslip.error("Programming error");
-            return;
-        }
+type List<Key> = {
+    scroll_container_sel: string;
+    find_li(opts: {key: Key; force_render: boolean}): JQuery;
+    first_key(): Key | undefined;
+    prev_key(key: Key): Key | undefined;
+    next_key(key: Key): Key | undefined;
+};
 
+export class ListCursor<Key> {
+    highlight_class: string;
+    list: List<Key>;
+    curr_key?: Key;
+
+    constructor({highlight_class, list}: {highlight_class: string; list: List<Key>}) {
         this.highlight_class = highlight_class;
         this.list = list;
     }
 
-    clear() {
+    clear(): void {
         if (this.curr_key === undefined) {
             return;
         }
@@ -33,11 +32,11 @@ export class ListCursor {
         this.curr_key = undefined;
     }
 
-    get_key() {
+    get_key(): Key | undefined {
         return this.curr_key;
     }
 
-    get_row(key) {
+    get_row(key: Key | undefined): {highlight(): void; clear(): void} | undefined {
         // TODO: The list class should probably do more of the work
         //       here, so we're not so coupled to jQuery, and
         //       so we instead just get back a widget we can say
@@ -69,12 +68,12 @@ export class ListCursor {
         };
     }
 
-    adjust_scroll($li) {
+    adjust_scroll($li: JQuery): void {
         const $scroll_container = $(this.list.scroll_container_sel);
         scroll_util.scroll_element_into_container($li, $scroll_container);
     }
 
-    redraw() {
+    redraw(): void {
         // We should only call this for situations like the buddy
         // list where we redraw the whole list without necessarily
         // changing it, so we just want to re-highlight the current
@@ -88,7 +87,7 @@ export class ListCursor {
         row.highlight();
     }
 
-    go_to(key) {
+    go_to(key: Key | undefined): void {
         if (key === undefined) {
             blueslip.error("Caller is not checking keys for ListCursor.go_to");
             return;
@@ -106,7 +105,7 @@ export class ListCursor {
         row.highlight();
     }
 
-    reset() {
+    reset(): void {
         this.clear();
         const key = this.list.first_key();
         if (key === undefined) {
@@ -116,7 +115,7 @@ export class ListCursor {
         this.go_to(key);
     }
 
-    prev() {
+    prev(): void {
         if (this.curr_key === undefined) {
             return;
         }
@@ -128,7 +127,7 @@ export class ListCursor {
         this.go_to(key);
     }
 
-    next() {
+    next(): void {
         if (this.curr_key === undefined) {
             // This is sort of a special case where we went from
             // an empty filter to having data.
diff --git a/web/src/stream_list.js b/web/src/stream_list.js
index 02254d7845..f1273d89e5 100644
--- a/web/src/stream_list.js
+++ b/web/src/stream_list.js
@@ -691,8 +691,8 @@ export function initialize_stream_cursor() {
             scroll_container_sel: "#left_sidebar_scroll_container",
             find_li(opts) {
                 const stream_id = opts.key;
-                const li = get_stream_li(stream_id);
-                return li;
+                const $li = get_stream_li(stream_id);
+                return $li;
             },
             first_key: stream_list_sort.first_stream_id,
             prev_key: stream_list_sort.prev_stream_id,
diff --git a/web/tests/list_cursor.test.js b/web/tests/list_cursor.test.js
index 5e9fa7b0bd..dc886d62d2 100644
--- a/web/tests/list_cursor.test.js
+++ b/web/tests/list_cursor.test.js
@@ -9,11 +9,6 @@ const $ = require("./lib/zjquery");
 
 const {ListCursor} = zrequire("list_cursor");
 
-run_test("config errors", () => {
-    blueslip.expect("error", "Programming error");
-    new ListCursor({});
-});
-
 function basic_conf({first_key, prev_key, next_key}) {
     const list = {
         scroll_container_sel: "whatever",