diff --git a/qt/aqt/data/web/js/reviewer.ts b/qt/aqt/data/web/js/reviewer.ts
index 5c6187dec..0d1985efc 100644
--- a/qt/aqt/data/web/js/reviewer.ts
+++ b/qt/aqt/data/web/js/reviewer.ts
@@ -27,7 +27,12 @@ function _queueAction(action: () => Promise<void>): void {
     _updatingQueue = _updatingQueue.then(action);
 }
 
-async function _updateQA(html, fadeTime, onupdate, onshown): Promise<void> {
+async function _updateQA(
+    html: string,
+    fadeTime: number,
+    onupdate: () => void,
+    onshown: () => void
+): Promise<void> {
     onUpdateHook = [onupdate];
     onShownHook = [onshown];
 
@@ -62,44 +67,48 @@ async function _updateQA(html, fadeTime, onupdate, onshown): Promise<void> {
     await _runHook(onShownHook);
 }
 
-function _showQuestion(q, bodyclass) {
-    _queueAction(() => _updateQA(
-        q,
-        qFade,
-        function () {
-            // return to top of window
-            window.scrollTo(0, 0);
+function _showQuestion(q: string, bodyclass: string): void {
+    _queueAction(() =>
+        _updateQA(
+            q,
+            qFade,
+            function () {
+                // return to top of window
+                window.scrollTo(0, 0);
 
-            document.body.className = bodyclass;
-        },
-        function () {
-            // focus typing area if visible
-            typeans = document.getElementById("typeans");
-            if (typeans) {
-                typeans.focus();
+                document.body.className = bodyclass;
+            },
+            function () {
+                // focus typing area if visible
+                typeans = document.getElementById("typeans");
+                if (typeans) {
+                    typeans.focus();
+                }
             }
-        }
-    ));
+        )
+    );
 }
 
-function _showAnswer(a, bodyclass) {
-    _queueAction(() => _updateQA(
-        a,
-        aFade,
-        function () {
-            if (bodyclass) {
-                //  when previewing
-                document.body.className = bodyclass;
-            }
+function _showAnswer(a: string, bodyclass: string): void {
+    _queueAction(() =>
+        _updateQA(
+            a,
+            aFade,
+            function () {
+                if (bodyclass) {
+                    //  when previewing
+                    document.body.className = bodyclass;
+                }
 
-            // scroll to answer?
-            var e = $("#answer");
-            if (e[0]) {
-                e[0].scrollIntoView();
-            }
-        },
-        function () {}
-    ));
+                // scroll to answer?
+                var e = $("#answer");
+                if (e[0]) {
+                    e[0].scrollIntoView();
+                }
+            },
+            function () {}
+        )
+    );
 }
 
 const _flagColours = {
@@ -109,7 +118,7 @@ const _flagColours = {
     4: "#77aaff",
 };
 
-function _drawFlag(flag) {
+function _drawFlag(flag: 0 | 1 | 2 | 3): void {
     var elem = $("#_flag");
     if (flag === 0) {
         elem.hide();
@@ -119,7 +128,7 @@ function _drawFlag(flag) {
     elem.css("color", _flagColours[flag]);
 }
 
-function _drawMark(mark) {
+function _drawMark(mark: boolean): void {
     var elem = $("#_mark");
     if (!mark) {
         elem.hide();
@@ -128,13 +137,13 @@ function _drawMark(mark) {
     }
 }
 
-function _typeAnsPress() {
+function _typeAnsPress(): void {
     if ((window.event as KeyboardEvent).keyCode === 13) {
         pycmd("ans");
     }
 }
 
-function _emulateMobile(enabled: boolean) {
+function _emulateMobile(enabled: boolean): void {
     const list = document.documentElement.classList;
     if (enabled) {
         list.add("mobile");