diff --git a/api.js b/api.js
index a54d8fe..da21e62 100644
--- a/api.js
+++ b/api.js
@@ -1,9 +1,20 @@
+/**
+ * Thrown when the passed URL is not a supported post URL on bsky.app.
+ */
+
 class URLError extends Error {
+
+  /** @param {string} message */
   constructor(message) {
     super(message);
   }
 }
 
+
+/**
+ * Caches the mapping of handles to DIDs to avoid unnecessary API calls to resolveHandle or getProfile.
+ */
+
 class HandleCache {
   prepareCache() {
     if (!this.cache) {
@@ -15,17 +26,23 @@ class HandleCache {
     localStorage.setItem('handleCache', JSON.stringify(this.cache));
   }
 
+  /** @param {string} handle, @returns {string | undefined}  */
+
   getHandleDid(handle) {
     this.prepareCache();
     return this.cache[handle];
   }
 
+  /** @param {string} handle, @param {string} did */
+
   setHandleDid(handle, did) {
     this.prepareCache();
     this.cache[handle] = did;
     this.saveCache();    
   }
 
+  /** @param {string} did, @returns {string | undefined}  */
+
   findHandleByDid(did) {
     this.prepareCache();
     let found = Object.entries(this.cache).find((e) => e[1] == did);
@@ -33,6 +50,11 @@ class HandleCache {
   }
 }
 
+
+/**
+ * Stores user's access tokens and data in local storage after they log in.
+ */
+
 class LocalStorageConfig {
   constructor() {
     this.user = {};
@@ -49,6 +71,8 @@ class LocalStorageConfig {
     this.saveItem('avatar', this.user.avatar);
   }
 
+  /** @param {string} key, @param {string | undefined} value */
+
   saveItem(key, value) {
     if (value !== undefined) {
       localStorage.setItem(key, value);
@@ -58,7 +82,14 @@ class LocalStorageConfig {
   }
 }
 
+
+/**
+ * API client for connecting to the Bluesky XRPC API (authenticated or not).
+ */
+
 class BlueskyAPI extends Minisky {
+
+  /** @param {string} host, @param {boolean} useAuthentication */
   constructor(host, useAuthentication) {
     super(host, useAuthentication ? new LocalStorageConfig() : undefined);
 
@@ -66,16 +97,22 @@ class BlueskyAPI extends Minisky {
     this.profiles = {};
   }
 
+  /** @param {object} author */
+
   cacheProfile(author) {
     this.profiles[author.did] = author;
     this.profiles[author.handle] = author;
     this.handleCache.setHandleDid(author.handle, author.did);
   }
 
+  /** @param {string} did, @returns {string | undefined} */
+
   findHandleByDid(did) {
     return this.handleCache.findHandleByDid(did);
   }
 
+  /** @param {string} string, @returns {[string, string]} */
+
   static parsePostURL(string) {
     let url;
 
@@ -105,6 +142,8 @@ class BlueskyAPI extends Minisky {
     return [handle, postId];
   }
 
+  /** @param {string} handle, @returns {Promise<string>} */
+
   async resolveHandle(handle) {
     let did = this.handleCache.getHandleDid(handle);
 
@@ -118,11 +157,15 @@ class BlueskyAPI extends Minisky {
     }
   }
 
+  /** @param {string} url, @returns {Promise<object>} */
+
   async loadThreadByURL(url) {
     let [handle, postId] = BlueskyAPI.parsePostURL(url);
     return await this.loadThreadById(handle, postId);
   }
 
+  /** @param {string} author, @param {string} postId, @returns {Promise<object>} */
+
   async loadThreadById(author, postId) {
     let did = author.startsWith('did:') ? author : await this.resolveHandle(author);
     let postURI = `at://${did}/app.bsky.feed.post/${postId}`;
@@ -130,6 +173,8 @@ class BlueskyAPI extends Minisky {
     return threadJSON;
   }
 
+  /** @param {string} handle, @returns {Promise<object>} */
+
   async loadUserProfile(handle) {
     if (this.profiles[handle]) {
       return this.profiles[handle];
@@ -140,6 +185,8 @@ class BlueskyAPI extends Minisky {
     }
   }
 
+  /** @returns {Promise<object>} */
+
   async loadCurrentUserAvatar() {
     let json = await this.getRequest('com.atproto.repo.getRecord', {
       repo: this.user.did,
@@ -150,11 +197,15 @@ class BlueskyAPI extends Minisky {
     return json.value.avatar;
   }
 
+  /** @param {string} uri, @returns {Promise<number>} */
+
   async getQuoteCount(uri) {
     let json = await this.getRequest('eu.mackuba.private.getQuoteCount', { uri });
     return json.quoteCount;
   }
 
+  /** @param {string} url, @returns {Promise<object>} */
+
   async getQuotes(url) {
     let [handle, postId] = BlueskyAPI.parsePostURL(url);
     let did = handle.startsWith('did:') ? handle : await appView.resolveHandle(handle);
@@ -164,21 +215,29 @@ class BlueskyAPI extends Minisky {
     return json;
   }
 
+  /** @param {string} hashtag, @returns {Promise<object[]>} */
+
   async getHashtagFeed(hashtag) {
     let json = await this.getRequest('eu.mackuba.private.getHashtagFeed', { tag: hashtag });
     return json.feed;
   }
 
+  /** @param {string} postURI, @returns {Promise<object>} */
+
   async loadPost(postURI) {
     let posts = await this.loadPosts([postURI]);
     return posts[0];
   }
 
+  /** @param {string[]} uris, @returns {Promise<object[]>} */
+
   async loadPosts(uris) {
     let response = await this.getRequest('app.bsky.feed.getPosts', { uris });
     return response.posts;
   }
 
+  /** @param {object} post, @returns {Promise<object>} */
+
   async likePost(post) {
     return await this.postRequest('com.atproto.repo.createRecord', {
       repo: this.user.did,
@@ -193,6 +252,8 @@ class BlueskyAPI extends Minisky {
     });
   }
 
+  /** @param {string} uri, @returns {Promise<object>} */
+
   async removeLike(uri) {
     let { rkey } = atURI(uri);
 
diff --git a/embed_component.js b/embed_component.js
index dd1395b..a79e90f 100644
--- a/embed_component.js
+++ b/embed_component.js
@@ -1,9 +1,17 @@
+/**
+ * Renders an embed (e.g. image or quoted post) inside the post view.
+ */
+
 class EmbedComponent {
+
+  /** @param {Post} post, @param {object} embed */
   constructor(post, embed) {
     this.post = post;
     this.embed = embed;
   }
 
+  /** @returns {AnyElement} */
+
   buildElement() {
     let wrapper, quoteView, mediaView;
 
@@ -48,12 +56,16 @@ class EmbedComponent {
     }
   }
 
+  /** @returns {AnyElement} */
+
   quotedPostPlaceholder() {
     return $tag('div.quote-embed', {
       html: '<p class="post placeholder">Loading quoted post...</p>'
     });
   }
 
+  /** @returns {AnyElement} */
+
   buildQuotedPostElement() {
     let div = $tag('div.quote-embed');
 
@@ -68,6 +80,8 @@ class EmbedComponent {
     return div;
   }
 
+  /** @returns {AnyElement} */
+
   buildLinkComponent() {
     let a = $tag('a', { href: this.embed.url, text: this.embed.title || this.embed.url });
 
@@ -76,6 +90,8 @@ class EmbedComponent {
     return p;
   }
 
+  /** @returns {AnyElement} */
+
   buildImagesComponent() {
     let wrapper = $tag('div');
 
@@ -110,6 +126,8 @@ class EmbedComponent {
     return wrapper;
   }
 
+  /** @param {string} uri, @param {AnyElement} div, @returns Promise<void> */
+
   async loadQuotedPost(uri, div) {
     let result = await api.loadPost(uri);
     let post = new Post(result, { isEmbed: true });
diff --git a/jsconfig.json b/jsconfig.json
index af564b9..cd4b961 100644
--- a/jsconfig.json
+++ b/jsconfig.json
@@ -1,7 +1,9 @@
 {
   "compilerOptions": {
     "target": "es2022",
-    "checkJs": true
+    "checkJs": true,
+    "strict": true,
+    "noImplicitAny": false
   },
   "include": ["*.js", "*.d.ts"]
 }
diff --git a/minisky.js b/minisky.js
index 6ffebc5..04b5c99 100644
--- a/minisky.js
+++ b/minisky.js
@@ -1,4 +1,10 @@
+/**
+ * Thrown when status code of an API response is not "success".
+ */
+
 class APIError extends Error {
+
+  /** @param {number} code, @param {object} json */
   constructor(code, json) {
     super("APIError status " + code + "\n\n" + JSON.stringify(json));
     this.code = code;
@@ -6,10 +12,27 @@ class APIError extends Error {
   }
 }
 
-class AuthError extends Error {
-}
+
+/**
+ * Thrown when authentication is needed, but access token is invalid or missing.
+ */
+
+class AuthError extends Error {}
+
+
+/**
+ * Base API client for connecting to an ATProto XRPC API.
+ */
 
 class Minisky {
+
+  /**
+   * @typedef {object} MiniskyOptions
+   * @prop {boolean} [sendAuthHeaders]
+   * @prop {boolean} [autoManageTokens]
+   *
+   * @param {string} host, @param {object} config, @param {MiniskyOptions} [options]
+   */
   constructor(host, config, options) {
     this.host = host;
     this.config = config;
@@ -24,10 +47,21 @@ class Minisky {
     }
   }
 
+  /** @returns {boolean} */
+
   get isLoggedIn() {
     return !!(this.user && this.user.accessToken && this.user.refreshToken && this.user.did);
   }
 
+  /**
+   * @typedef {object} MiniskyRequestOptions
+   * @prop {string | boolean} [auth]
+   * @prop {Record<string, string>} [headers]
+   *
+   * @param {string} method, @param {object} params, @param {MiniskyRequestOptions} [options]
+   * @returns {Promise<object>}
+   */
+
   async getRequest(method, params, options) {
     let url = new URL(`${this.baseURL}/${method}`);
     let auth = options && ('auth' in options) ? options.auth : this.sendAuthHeaders;
@@ -56,6 +90,11 @@ class Minisky {
     return await this.parseResponse(response);
   }
 
+  /**
+   * @param {string} method, @param {object} [data], @param {MiniskyRequestOptions} [options]
+   * @returns Promise<object>
+   */
+
   async postRequest(method, data, options) {
     let url = `${this.baseURL}/${method}`;
     let auth = options && ('auth' in options) ? options.auth : this.sendAuthHeaders;
@@ -79,10 +118,8 @@ class Minisky {
     return await this.parseResponse(response);
   }
 
-  /**
-   * @param {string | boolean} auth
-   * @returns {Record<string, string>}
-   */
+  /** @param {string | boolean} auth, @returns {Record<string, string>} */
+
   authHeaders(auth) {
     if (typeof auth == 'string') {
       return { 'Authorization': `Bearer ${auth}` };
@@ -97,6 +134,8 @@ class Minisky {
     }
   }
 
+  /** @param {string} token, @returns {number} */
+
   tokenExpirationTimestamp(token) {
     let parts = token.split('.');
     if (parts.length != 3) {
@@ -113,10 +152,14 @@ class Minisky {
     return exp * 1000;
   }
 
+  /** @param {Response} response, @param {object} json, @returns {boolean} */
+
   isInvalidToken(response, json) {
     return (response.status == 400) && json && ['InvalidToken', 'ExpiredToken'].includes(json.error);
   }
 
+  /** @param {Response} response, @returns {Promise<object>} */
+
   async parseResponse(response) {
     let text = await response.text();
     let json = text.trim().length > 0 ? JSON.parse(text) : undefined;
@@ -128,6 +171,8 @@ class Minisky {
     }
   }
 
+  /** @returns {Promise<void>} */
+
   async checkAccess() {
     if (!this.isLoggedIn) {
       throw new AuthError("Not logged in");
@@ -140,6 +185,8 @@ class Minisky {
     }
   }
 
+  /** @param {string} handle, @param {string} password, @returns {Promise<object>} */
+
   async logIn(handle, password) {
     let params = { identifier: handle, password: password };
     let json = await this.postRequest('com.atproto.server.createSession', params, { auth: false });
@@ -148,6 +195,8 @@ class Minisky {
     return json;
   }
 
+  /** @returns {Promise<object>} */
+
   async performTokenRefresh() {
     console.log('Refreshing access token…');
     let json = await this.postRequest('com.atproto.server.refreshSession', null, { auth: this.user.refreshToken });
@@ -155,6 +204,8 @@ class Minisky {
     return json;
   }
 
+  /** @param {object} json */
+
   saveTokens(json) {
     this.user.accessToken = json['accessJwt'];
     this.user.refreshToken = json['refreshJwt'];
diff --git a/models.js b/models.js
index 9b4058c..8632774 100644
--- a/models.js
+++ b/models.js
@@ -1,4 +1,10 @@
+/**
+ * Generic record type, base class for all records.
+ */
+
 class ATProtoRecord {
+
+  /** @param {object} data, @param {object} [extra] */
   constructor(data, extra) {
     this.data = data;
 
@@ -7,27 +13,40 @@ class ATProtoRecord {
     }
   }
 
+  /** @returns {string} */
   get uri() {
     return this.data.uri;
   }
 
+  /** @returns {string} */
   get cid() {
     return this.data.cid;
   }
 
+  /** @returns {string} */
   get rkey() {
     return atURI(this.uri).rkey;
   }
 
+  /** @returns {string} */
   get type() {
     return this.data.$type;
   }
 }
 
+
+/**
+ * Standard Bluesky post record.
+ */
+
 class Post extends ATProtoRecord {
+  /** @type {ATProtoRecord | undefined} */
   parent;
+
+  /** @type {object | undefined} */
   reason;
 
+  /** @param {object} json, @returns {ATProtoRecord} */
   static parse(json) {
     let post;
 
@@ -75,6 +94,7 @@ class Post extends ATProtoRecord {
     }
   }
 
+  /** @param {object} data, @param {object} [extra] */
   constructor(data, extra) {
     super(data, extra);
 
@@ -98,60 +118,81 @@ class Post extends ATProtoRecord {
     }
   }
 
+  /** @returns {string} */
   get text() {
     return this.record.text;
   }
 
+  /** @returns {object} */
   get facets() {
     return this.record.facets;
   }
 
+  /** @returns {Date} */
   get createdAt() {
     return new Date(this.record.createdAt);
   }
 
+  /** @returns {number} */
   get likeCount() {
     return this.data.likeCount;
   }
 
+  /** @returns {number} */
   get replyCount() {
     return this.data.replyCount;
   }
 
+  /** @returns {boolean} */
   get hasMoreReplies() {
     return this.replyCount !== undefined && this.replyCount !== this.replies.length;
   }
 
+  /** @returns {number} */
   get repostCount() {
     return this.data.repostCount;
   }
 
+  /** @returns {boolean} */
   get liked() {
     return (this.viewerLike !== undefined);
   }
 
+  /** @returns {boolean | undefined} */
   get muted() {
     return this.author.viewer?.muted;
   }
 
+  /** @returns {string | undefined} */
   get muteList() {
     return this.author.viewer?.mutedByList?.name;
   }
 
+  /** @returns {boolean} */
   get hasViewerInfo() {
     return (this.viewerData !== undefined);
   }
 
+  /** @returns {ATProtoRecord | undefined} */
   get parentReference() {
     return this.record.reply?.parent && new ATProtoRecord(this.record.reply?.parent);
   }
 
+  /** @returns {ATProtoRecord | undefined} */
   get rootReference() {
     return this.record.reply?.root && new ATProtoRecord(this.record.reply?.root);
   }
 }
 
+
+/**
+ * Post which is blocked for some reason (the author is blocked, the author has blocked you, or there is a block
+ * between the post author and the parent author). It only includes a reference, but no post content.
+ */
+
 class BlockedPost extends ATProtoRecord {
+
+  /** @param {object} data */
   constructor(data) {
     super(data);
 
@@ -160,16 +201,25 @@ class BlockedPost extends ATProtoRecord {
     this.author = data.author;
   }
 
+  /** @returns {boolean} */
   get blocksUser() {
     return !!this.author.viewer?.blocking;
   }
 
+  /** @returns {boolean} */
   get blockedByUser() {
     return this.author.viewer?.blockedBy;
   }
 }
 
+
+/**
+ * Base class for embed objects.
+ */
+
 class Embed {
+
+  /** @param {object} json, @returns {Embed} */
   static parse(json) {
     switch (json.$type) {
     case 'app.bsky.embed.record':
@@ -201,16 +251,20 @@ class Embed {
     }
   }
 
+  /** @param {object} json */
   constructor(json) {
     this.json = json;
   }
 
+  /** @returns {string} */
   get type() {
     return this.json.$type;
   }
 }
 
 class ImageEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.images = json.images;
@@ -218,6 +272,8 @@ class ImageEmbed extends Embed {
 }
 
 class LinkEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
 
@@ -227,6 +283,8 @@ class LinkEmbed extends Embed {
 }
 
 class RecordEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.record = new ATProtoRecord(json.record);
@@ -234,6 +292,8 @@ class RecordEmbed extends Embed {
 }
 
 class RecordWithMediaEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.record = new ATProtoRecord(json.record.record);
@@ -242,6 +302,8 @@ class RecordWithMediaEmbed extends Embed {
 }
 
 class InlineRecordEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.post = Post.parse(json.record);
@@ -249,6 +311,8 @@ class InlineRecordEmbed extends Embed {
 }
 
 class InlineRecordWithMediaEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.post = Post.parse(json.record.record);
@@ -257,6 +321,8 @@ class InlineRecordWithMediaEmbed extends Embed {
 }
 
 class InlineLinkEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
 
@@ -266,12 +332,17 @@ class InlineLinkEmbed extends Embed {
 }
 
 class InlineImageEmbed extends Embed {
+
+  /** @param {object} json */
   constructor(json) {
     super(json);
     this.images = json.images;
   }
 }
 
+// TODO
+/** @param {object} a, @param {object} b, @param {Post} parent, @returns {-1 | 0 | 1} */
+
 function sortReplies(a, b, parent) {
   if (a.missing && b.missing) {
     return 0;
diff --git a/post_component.js b/post_component.js
index 2fe704f..dcd2e31 100644
--- a/post_component.js
+++ b/post_component.js
@@ -1,28 +1,38 @@
+/**
+ * Renders a post/thread view and its subviews.
+ */
+
 class PostComponent {
+  /** @param {Post} post, @param {Post} [root] */
   constructor(post, root) {
     this.post = post;
     this.root = root ?? post;
     this.isRoot = (this.post === this.root);
   }
 
+  /** @returns {string} */
   get linkToAuthor() {
     return 'https://bsky.app/profile/' + this.post.author.handle;
   }
 
+  /** @returns {string} */
   get linkToPost() {
     return this.linkToAuthor + '/post/' + this.post.rkey;
   }
 
+  /** @returns {string} */
   get didLinkToAuthor() {
     let { repo } = atURI(this.post.uri);
     return `https://bsky.app/profile/${repo}`;
   }
 
+  /** @returns {string} */
   get didLinkToPost() {
     let { repo, rkey } = atURI(this.post.uri);
     return `https://bsky.app/profile/${repo}/post/${rkey}`;
   }
 
+  /** @returns {string} */
   get authorName() {
     if (this.post.author.displayName) {
       return this.post.author.displayName;
@@ -33,6 +43,7 @@ class PostComponent {
     }
   }
 
+  /** @returns {object} */
   get timeFormatForTimestamp() {
     if (this.isRoot) {
       return { day: 'numeric', month: 'short', year: 'numeric', hour: 'numeric', minute: 'numeric' };
@@ -50,7 +61,12 @@ class PostComponent {
     - quote - a quote embed
     - quotes - a post on the quotes page
     - feed - a post on the hashtag feed page
+
+    @typedef {'thread' | 'parent' | 'quote' | 'quotes' | 'feed'} PostContext
+    @param {PostContext} context
+    @returns {AnyElement}
   */
+
   buildElement(context) {
     let div = $tag('div.post');
 
@@ -137,6 +153,8 @@ class PostComponent {
     return div;
   }
 
+  /** @param {PostContext} context, @returns {AnyElement} */
+
   buildPostHeader(context) {
     let timeFormat = this.timeFormatForTimestamp;
     let formattedTime = this.post.createdAt.toLocaleString(window.dateLocale, timeFormat);
@@ -167,6 +185,8 @@ class PostComponent {
     return h;
   }
 
+  /** @param {string} url, @returns {HTMLImageElement} */
+
   buildUserAvatar(url) {
     let avatar = $tag('img.avatar', { src: url });
     let tries = 0;
@@ -184,6 +204,8 @@ class PostComponent {
     return avatar;
   }
 
+  /** @returns {AnyElement} */
+
   buildPostBody() {
     let p = $tag('p.body');
     let richText = new RichText({ text: this.post.text, facets: this.post.facets });
@@ -205,6 +227,8 @@ class PostComponent {
     return p;
   }
 
+  /** @returns {AnyElement} */
+
   buildStatsFooter() {
     let stats = $tag('p.stats');
 
@@ -223,6 +247,8 @@ class PostComponent {
     return stats;
   }
 
+  /** @returns {AnyElement} */
+
   buildLoadMoreLink() {
     let loadMore = $tag('p');
 
@@ -241,6 +267,8 @@ class PostComponent {
     return loadMore;
   }
 
+  /** @param {AnyElement} div, @returns {AnyElement} */
+
   buildBlockedPostElement(div) {
     let p = $tag('p.blocked-header');
     p.innerHTML = `<i class="fa-solid fa-ban"></i> <span>Blocked post</span> ` +
@@ -285,6 +313,8 @@ class PostComponent {
     return div;
   }
 
+  /** @param {string} uri, @param {AnyElement} div, @returns Promise<void> */
+
   async loadBlockedPost(uri, div) {
     let record = await appView.loadPost(this.post.uri);
     this.post = new Post(record);
@@ -306,6 +336,8 @@ class PostComponent {
     div.appendChild(p);
   }
 
+  /** @param {AnyElement} div */
+
   toggleSectionFold(div) {
     let plus = div.querySelector('.plus');
 
@@ -318,6 +350,8 @@ class PostComponent {
     }
   }
 
+  /** @param {AnyElement} heart */
+
   onHeartClick(heart) {
     if (!this.post.hasViewerInfo) {
       showLogin();
diff --git a/rich_text_lite.js b/rich_text_lite.js
index 62c8131..3af55f2 100644
--- a/rich_text_lite.js
+++ b/rich_text_lite.js
@@ -26,25 +26,30 @@
 // packages/api/src/rich-text/rich-text.ts
 
 class RichTextSegment {
+  /** @param {string} text, @param {object} [facet] */
   constructor(text, facet) {
     this.text = text;
     this.facet = facet;
   }
 
+  /** @returns {object | undefined} */
   get link() {
     return this.facet?.features?.find(v => v.$type === 'app.bsky.richtext.facet#link');
   }
 
+  /** @returns {object | undefined} */
   get mention() {
     return this.facet?.features?.find(v => v.$type === 'app.bsky.richtext.facet#mention');
   }
 
+  /** @returns {object | undefined} */
   get tag() {
     return this.facet?.features?.find(v => v.$type === 'app.bsky.richtext.facet#tag');
   }
 }
 
 class RichText {
+  /** @params {object} props */
   constructor(props) {
     this.unicodeText = new UnicodeString(props.text);
     this.facets = props.facets;
@@ -54,14 +59,17 @@ class RichText {
     }
   }
 
+  /** @returns {string} */
   get text() {
     return this.unicodeText.toString();
   }
 
+  /** @returns {number} */
   get length() {
     return this.unicodeText.length;
   }
 
+  /** @returns {number} */
   get graphemeLength() {
     return this.unicodeText.graphemeLength;
   }
@@ -125,23 +133,28 @@ class UnicodeString {
   static decoder = new TextDecoder();
   static segmenter = window.Intl && Intl.Segmenter && new Intl.Segmenter();
 
+  /** @param {string} utf16 */
   constructor(utf16) {
     this.utf16 = utf16;
     this.utf8 = UnicodeString.encoder.encode(utf16);
   }
 
+  /** @returns number */
   get length() {
     return this.utf8.byteLength;
   }
 
+  /** @returns number */
   get graphemeLength() {
     return Array.from(UnicodeString.segmenter.segment(this.utf16)).length;
   }
 
+  /** @param {number} start, @param {number} end, @returns string */
   slice(start, end) {
     return UnicodeString.decoder.decode(this.utf8.slice(start, end));
   }
 
+  /** @returns string */
   toString() {
     return this.utf16;
   }
diff --git a/skythread.js b/skythread.js
index 42c6f8a..f67a56a 100644
--- a/skythread.js
+++ b/skythread.js
@@ -88,6 +88,8 @@ function parseQueryParams() {
   }
 }
 
+/** @param {Post} post, @returns {AnyElement} */
+
 function buildParentLink(post) {
   let p = $tag('p.back');
 
@@ -154,6 +156,8 @@ function toggleAccount() {
   menu.style.visibility = (menu.style.visibility == 'visible') ? 'hidden' : 'visible';
 }
 
+/** @param {string} [avatar] */
+
 function showLoggedInStatus(avatar) {
   let account = $id('account');
 
@@ -258,10 +262,14 @@ function submitSearch() {
   }
 }
 
+/** @param {Post} post */
+
 function setPageTitle(post) {
   document.title = `${post.author.displayName}: "${post.text}" - Skythread`;
 }
 
+/** @param {string} hashtag */
+
 function loadHashtagPage(hashtag) {
   hashtag = hashtag.replace(/^\#/, '');
   document.title = `#${hashtag} - Skythread`;
@@ -306,6 +314,8 @@ function loadHashtagPage(hashtag) {
   });
 }
 
+/** @param {string} url */
+
 function loadQuotesPage(url) {
   blue.getQuotes(url).then(data => {
     let uris = data.posts;
@@ -363,6 +373,8 @@ function loadQuotesPage(url) {
   });
 }
 
+/** @param {string[]} uris, @param {(p: object[]) => void} callback, @returns Promise<void> */
+
 async function loadPostsInBatches(uris, callback) {
   if (uris.length > 0) {
     for (let i = 0; i < uris.length; i += 25) {
@@ -374,6 +386,8 @@ async function loadPostsInBatches(uris, callback) {
   }
 }
 
+/** @param {string} url, @param {string} [postId], @param {AnyElement} [nodeToUpdate] */
+
 function loadThread(url, postId, nodeToUpdate) {
   let load = postId ? api.loadThreadById(url, postId) : api.loadThreadByURL(url);
 
diff --git a/types.d.ts b/types.d.ts
index 5ee69a3..12665b4 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -8,3 +8,24 @@ declare var api: BlueskyAPI;
 declare var blue: BlueskyAPI;
 declare var appView: BlueskyAPI;
 
+type SomeElement = Element | HTMLElement | AnyElement;
+
+interface AnyElement {
+  classList: CSSClassList;
+  className: string;
+  innerText: string;
+  nextElementSibling: AnyElement;
+  parentNode: AnyElement;
+  src: string;
+
+  addEventListener<K extends keyof DocumentEventMap>(
+    type: K, listener: EventListenerOrEventListenerObject
+  ): void;
+
+  append(e: string | SomeElement): void;
+  appendChild(e: SomeElement): void;
+  querySelector(q: string): AnyElement;
+  remove(): void;
+  replaceChildren(e: SomeElement): void;
+  replaceWith(e: SomeElement): void;
+}
diff --git a/utils.js b/utils.js
index f268d2f..bd4f5f7 100644
--- a/utils.js
+++ b/utils.js
@@ -1,3 +1,24 @@
+class AtURI {
+  /** @param {string} uri */
+  constructor(uri) {
+    if (!uri.startsWith('at://')) {
+      throw new URLError(`Not an at:// URI: ${uri}`);
+    }
+
+    let parts = uri.split('/');
+
+    if (parts.length != 5) {
+      throw new URLError(`Invalid at:// URI: ${uri}`);
+    }
+
+    this.repo = parts[2];
+    this.collection = parts[3];
+    this.rkey = parts[4];
+  }
+}
+
+/** @param {string} tag, @param {string | object} [params], @returns {any} */
+
 function $tag(tag, params) {
   let element;
 
@@ -27,35 +48,19 @@ function $tag(tag, params) {
   return element;
 }
 
-/**
-  * @param {string} name
-  * @returns {any}
-  */
+/** @param {string} name, @returns {any} */
+
 function $id(name) {
   return document.getElementById(name);
 }
 
+/** @param {string} uri, @returns {AtURI} */
+
 function atURI(uri) {
   return new AtURI(uri);
 }
 
-class AtURI {
-  constructor(uri) {
-    if (!uri.startsWith('at://')) {
-      throw new URLError(`Not an at:// URI: ${uri}`);
-    }
-
-    let parts = uri.split('/');
-
-    if (parts.length != 5) {
-      throw new URLError(`Invalid at:// URI: ${uri}`);
-    }
-
-    this.repo = parts[2];
-    this.collection = parts[3];
-    this.rkey = parts[4];
-  }
-}
+/** @param {string} html, @returns {string} */
 
 function escapeHTML(html) {
   return html.replace(/&/g, '&amp;')
@@ -63,10 +68,14 @@ function escapeHTML(html) {
              .replace(/>/g,'&gt;');
 }
 
+/** @returns {string} */
+
 function getLocation() {
   return location.origin + location.pathname;
 }
 
+/** @param {Date} date1, @param {Date} date2, @returns {boolean} */
+
 function sameDay(date1, date2) {
   return (
     date1.getDate() == date2.getDate() &&
@@ -75,10 +84,14 @@ function sameDay(date1, date2) {
   );
 }
 
+/** @param {Post} post, @returns {string} */
+
 function linkToPostThread(post) {
   return linkToPostById(post.author.handle, post.rkey);
 }
 
+/** @param {string} handle, @param {string} postId, @returns {string} */
+
 function linkToPostById(handle, postId) {
   let url = new URL(getLocation());
   url.searchParams.set('author', handle);