ts: Convert ui_util module to TypeScript.

static/js/global.d.ts

@@ -7,4 +7,5 @@ declare let zulip_test: any;
 
 interface JQuery {
     expectOne(): JQuery;
+    tab(action?: string): this; // From static/third/bootstrap
 }

static/js/ui_util.ts

@@ -3,28 +3,30 @@ import $ from "jquery";
 // Add functions to this that have no non-trivial
 // dependencies other than jQuery.
 
-export function change_tab_to(tabname) {
+export function change_tab_to(tabname: string): void {
     $(`#gear-menu a[href="${CSS.escape(tabname)}"]`).tab("show");
 }
 
 // https://stackoverflow.com/questions/4233265/contenteditable-set-caret-at-the-end-of-the-text-cross-browser
-export function place_caret_at_end(el) {
+export function place_caret_at_end(el: HTMLElement): void {
     el.focus();
 
     const range = document.createRange();
     range.selectNodeContents(el);
     range.collapse(false);
     const sel = window.getSelection();
-    sel.removeAllRanges();
-    sel.addRange(range);
+    sel?.removeAllRanges();
+    sel?.addRange(range);
 }
 
-export function blur_active_element() {
+export function blur_active_element(): void {
     // this blurs anything that may perhaps be actively focused on.
+    if (document.activeElement instanceof HTMLElement) {
         document.activeElement.blur();
     }
+}
 
-export function convert_enter_to_click(e) {
+export function convert_enter_to_click(e: JQuery.KeyDownEvent): void {
     if (e.key === "Enter") {
         e.preventDefault();
         e.stopPropagation();
@@ -32,7 +34,7 @@ export function convert_enter_to_click(e) {
     }
 }
 
-export function update_unread_count_in_dom(unread_count_elem, count) {
+export function update_unread_count_in_dom(unread_count_elem: JQuery, count: number): void {
     // This function is used to update unread count in top left corner
     // elements.
     const unread_count_span = unread_count_elem.find(".unread_count");

tools/test-js-with-node

@@ -166,7 +166,7 @@ EXEMPT_FILES = {
     "static/js/ui_init.js",
     "static/js/ui.js",
     "static/js/ui_report.ts",
-    "static/js/ui_util.js",
+    "static/js/ui_util.ts",
     "static/js/unread_ops.js",
     "static/js/unread_ui.js",
     "static/js/upload_widget.js",