diff --git a/public/scripts/AppCollapsible.js b/public/scripts/AppCollapsible.js
index 02003ee..67e963f 100644
--- a/public/scripts/AppCollapsible.js
+++ b/public/scripts/AppCollapsible.js
@@ -1,3 +1,6 @@
+/**
+ * @param {HTMLElement} el
+ */
 export function AppCollapsible(el) {
   const state = {
     show: true,
diff --git a/public/scripts/AppDatePicker.js b/public/scripts/AppDatePicker.js
index 6f8233a..5dad4af 100644
--- a/public/scripts/AppDatePicker.js
+++ b/public/scripts/AppDatePicker.js
@@ -17,6 +17,9 @@ const datesRow = `
   </tr>
 `;
 
+/**
+ * @param {HTMLElement} el
+ */
 export function AppDatePicker(el) {
   const now = new Date();
   const state = {
diff --git a/public/scripts/AppDraggable.js b/public/scripts/AppDraggable.js
index 885db05..055cbe3 100644
--- a/public/scripts/AppDraggable.js
+++ b/public/scripts/AppDraggable.js
@@ -1,3 +1,11 @@
+/**
+ * @param {HTMLElement} el
+ * @param {{
+ *  dropSelector: string;
+ *  dragThreshold?: number;
+ *  dropRange?: number;
+ * }} options
+ */
 export function AppDraggable(el, options) {
   const dragThreshold = options.dragThreshold ?? 5;
   const dropRange = options.dropRange ?? 50;
diff --git a/public/scripts/AppFlip.js b/public/scripts/AppFlip.js
index 6800abd..5d8f013 100644
--- a/public/scripts/AppFlip.js
+++ b/public/scripts/AppFlip.js
@@ -1,3 +1,11 @@
+/**
+ * @param {HTMLElement} el
+ * @param {{
+ *  initialDelay?: number;
+ *  removeTimeout: number;
+ *  selector: string;
+ * }} options
+ */
 export function AppFlip(el, options) {
   let enabled = options.initialDelay === 0;
   let first;
diff --git a/public/scripts/AppFps.js b/public/scripts/AppFps.js
index fe9a461..7a77f40 100644
--- a/public/scripts/AppFps.js
+++ b/public/scripts/AppFps.js
@@ -1,3 +1,6 @@
+/**
+ * @param {HTMLElement} el
+ */
 export function AppFps(el) {
   const sampleSize = 20;
   let times = [];
diff --git a/public/scripts/AppIcon.js b/public/scripts/AppIcon.js
index 1233bc9..484211d 100644
--- a/public/scripts/AppIcon.js
+++ b/public/scripts/AppIcon.js
@@ -2,6 +2,9 @@ export const BASE_URL = 'https://unpkg.com/@primer/octicons@19.8.0/build/svg/';
 
 const cache = {};
 
+/**
+ * @param {HTMLElement} el
+ */
 export function AppIcon(el) {
   if (el.children.length > 0) return;
 
diff --git a/public/scripts/AppSortable.js b/public/scripts/AppSortable.js
index fa16379..d86da53 100644
--- a/public/scripts/AppSortable.js
+++ b/public/scripts/AppSortable.js
@@ -1,3 +1,9 @@
+/**
+ * @param {HTMLElement} el
+ * @param {{
+ *  direction?: 'horizontal' | 'vertical';
+ * }} options
+ */
 export function AppSortable(el, options) {
   let placeholder;
   let placeholderSource;
diff --git a/public/scripts/TodoApp.js b/public/scripts/TodoApp.js
index 1f0a937..b4b971e 100644
--- a/public/scripts/TodoApp.js
+++ b/public/scripts/TodoApp.js
@@ -7,6 +7,9 @@ import { TodoFrameDays } from './TodoFrameDays.js';
 import { TodoStore } from './TodoStore.js';
 import { formatDateId } from './util.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoApp(el) {
   const state = {
     items: [],
diff --git a/public/scripts/TodoCustomList.js b/public/scripts/TodoCustomList.js
index f3f9452..71458eb 100644
--- a/public/scripts/TodoCustomList.js
+++ b/public/scripts/TodoCustomList.js
@@ -2,6 +2,9 @@ import { AppDraggable } from './AppDraggable.js';
 import { AppIcon } from './AppIcon.js';
 import { TodoList } from './TodoList.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoCustomList(el) {
   const state = {
     list: null,
diff --git a/public/scripts/TodoDay.js b/public/scripts/TodoDay.js
index 263aaee..c4d45ac 100644
--- a/public/scripts/TodoDay.js
+++ b/public/scripts/TodoDay.js
@@ -1,6 +1,9 @@
 import { TodoList } from './TodoList.js';
 import { formatDate, formatDayOfWeek } from './util.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoDay(el) {
   const state = {
     dateId: el.dataset.key,
diff --git a/public/scripts/TodoFrameCustom.js b/public/scripts/TodoFrameCustom.js
index efee7e1..bc8d5aa 100644
--- a/public/scripts/TodoFrameCustom.js
+++ b/public/scripts/TodoFrameCustom.js
@@ -2,6 +2,9 @@ import { AppIcon } from './AppIcon.js';
 import { AppSortable } from './AppSortable.js';
 import { TodoCustomList } from './TodoCustomList.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoFrameCustom(el) {
   const state = {
     customLists: [],
diff --git a/public/scripts/TodoFrameDays.js b/public/scripts/TodoFrameDays.js
index 64bcf9c..62a4b3c 100644
--- a/public/scripts/TodoFrameDays.js
+++ b/public/scripts/TodoFrameDays.js
@@ -3,6 +3,9 @@ import { AppIcon } from './AppIcon.js';
 import { TodoDay } from './TodoDay.js';
 import { formatDateId } from './util.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoFrameDays(el) {
   const RANGE = 14;
   const state = {
diff --git a/public/scripts/TodoItem.js b/public/scripts/TodoItem.js
index cb3dc52..b92ca20 100644
--- a/public/scripts/TodoItem.js
+++ b/public/scripts/TodoItem.js
@@ -1,6 +1,9 @@
 import { AppDraggable } from './AppDraggable.js';
 import { AppIcon } from './AppIcon.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoItem(el) {
   const state = {
     item: null,
diff --git a/public/scripts/TodoItemInput.js b/public/scripts/TodoItemInput.js
index 9a9d338..96b87ca 100644
--- a/public/scripts/TodoItemInput.js
+++ b/public/scripts/TodoItemInput.js
@@ -1,5 +1,8 @@
 import { AppIcon } from './AppIcon.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoItemInput(el) {
   let saveOnBlur = true;
 
diff --git a/public/scripts/TodoList.js b/public/scripts/TodoList.js
index c476356..489ce8f 100644
--- a/public/scripts/TodoList.js
+++ b/public/scripts/TodoList.js
@@ -2,6 +2,9 @@ import { AppSortable } from './AppSortable.js';
 import { TodoItem } from './TodoItem.js';
 import { TodoItemInput } from './TodoItemInput.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoList(el) {
   const state = {
     items: [],
diff --git a/public/scripts/TodoStore.js b/public/scripts/TodoStore.js
index b77733b..c8e07dd 100644
--- a/public/scripts/TodoStore.js
+++ b/public/scripts/TodoStore.js
@@ -1,5 +1,8 @@
 import { formatDateId, uuid } from './util.js';
 
+/**
+ * @param {HTMLElement} el
+ */
 export function TodoStore(el) {
   const state = {
     items: [],
diff --git a/public/scripts/util.js b/public/scripts/util.js
index c9bb47b..0388ca1 100644
--- a/public/scripts/util.js
+++ b/public/scripts/util.js
@@ -7,6 +7,10 @@ export function uuid() {
   });
 }
 
+/**
+ * @param {Date} date
+ * @returns {string}
+ */
 export function formatDateId(date) {
   const y = date.getFullYear();
   const m = date.getMonth() + 1;
@@ -18,6 +22,10 @@ export function formatDateId(date) {
   return `${ys}-${ms}-${ds}`;
 }
 
+/**
+ * @param {Date} date
+ * @returns {string}
+ */
 export function formatDate(date) {
   const m = formatMonth(date);
   const d = formatDayOfMonth(date);
@@ -26,6 +34,10 @@ export function formatDate(date) {
   return `${m} ${d} ${y}`;
 }
 
+/**
+ * @param {Date} date
+ * @returns {string}
+ */
 export function formatDayOfMonth(date) {
   const d = date.getDate();
   const t = d % 10;
@@ -51,6 +63,10 @@ export const DAY_NAMES = [
   'Saturday',
 ];
 
+/**
+ * @param {Date} date
+ * @returns {string}
+ */
 export function formatDayOfWeek(date) {
   return DAY_NAMES[date.getDay()];
 }
@@ -70,6 +86,10 @@ export const MONTH_NAMES = [
   'December',
 ];
 
+/**
+ * @param {Date} date
+ * @returns {string}
+ */
 export function formatMonth(date) {
   return MONTH_NAMES[date.getMonth()];
 }