pm_list_dom: Convert module to TypeScript.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

tools/test-js-with-node

@@ -142,7 +142,7 @@ EXEMPT_FILES = make_set(
         "web/src/playground_links_popover.js",
         "web/src/plotly.js.d.ts",
         "web/src/pm_list.js",
-        "web/src/pm_list_dom.js",
+        "web/src/pm_list_dom.ts",
         "web/src/poll_widget.js",
         "web/src/popover_menus.js",
         "web/src/popover_menus_data.js",

web/src/pm_list_dom.ts

@@ -5,10 +5,19 @@ import render_pm_list_item from "../templates/pm_list_item.hbs";
 
 import * as vdom from "./vdom";
 
-export function keyed_pm_li(conversation) {
+// TODO/typescript: Move this to pm_list_data
-    const render = () => render_pm_list_item(conversation);
+type PMListConversation = {
+    user_ids_string: string;
+};
 
-    const eq = (other) => _.isEqual(conversation, other.conversation);
+type PMNode = vdom.Node & {
+    conversation: PMListConversation;
+};
+
+export function keyed_pm_li(conversation: PMListConversation): PMNode {
+    const render = (): string => render_pm_list_item(conversation);
+
+    const eq = (other: PMNode): boolean => _.isEqual(conversation, other.conversation);
 
     const key = conversation.user_ids_string;
 
@@ -20,12 +29,20 @@ export function keyed_pm_li(conversation) {
     };
 }
 
-export function more_private_conversations_li(more_conversations_unread_count) {
+type MorePrivateConversationsNode = vdom.Node & {
-    const render = () => render_more_private_conversations({more_conversations_unread_count});
+    more_items: boolean;
+    more_conversations_unread_count: number;
+};
+
+export function more_private_conversations_li(
+    more_conversations_unread_count: number,
+): MorePrivateConversationsNode {
+    const render = (): string =>
+        render_more_private_conversations({more_conversations_unread_count});
 
     // Used in vdom.js to check if an element has changed and needs to
     // be updated in the DOM.
-    const eq = (other) =>
+    const eq = (other: MorePrivateConversationsNode): boolean =>
         other.more_items &&
         more_conversations_unread_count === other.more_conversations_unread_count;
 
@@ -41,8 +58,8 @@ export function more_private_conversations_li(more_conversations_unread_count) {
     };
 }
 
-export function pm_ul(nodes) {
+export function pm_ul(nodes: vdom.Node[]): vdom.Tag {
-    const attrs = [
+    const attrs: [string, string][] = [
         ["class", "pm-list"],
         ["data-name", "private"],
     ];

web/src/vdom.ts

@@ -151,7 +151,7 @@ export function update(
         like `attrs` for attributes.
 
         For examples of creating vdom objects, look at
-        `pm_list_dom.js`.
+        `pm_list_dom.ts`.
     */
     function do_full_update(): void {
         const rendered_dom = render_tag(new_dom);