diff --git a/extensions/flags/js/src/forum/components/FlagList.js b/extensions/flags/js/src/forum/components/FlagList.js
index 115df12ad..adfe2ccc6 100644
--- a/extensions/flags/js/src/forum/components/FlagList.js
+++ b/extensions/flags/js/src/forum/components/FlagList.js
@@ -13,6 +13,9 @@ export default class FlagList extends Component {
     this.state = this.attrs.state;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const flags = this.state.cache || [];
 
diff --git a/extensions/flags/js/src/forum/components/FlagPostModal.js b/extensions/flags/js/src/forum/components/FlagPostModal.js
index 49e438cd1..b28982669 100644
--- a/extensions/flags/js/src/forum/components/FlagPostModal.js
+++ b/extensions/flags/js/src/forum/components/FlagPostModal.js
@@ -24,6 +24,9 @@ export default class FlagPostModal extends Modal {
     return app.translator.trans('flarum-flags.forum.flag_post.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.success) {
       return (
diff --git a/extensions/flags/js/src/forum/components/FlagsDropdown.js b/extensions/flags/js/src/forum/components/FlagsDropdown.js
index 72b249a59..a161d92bf 100644
--- a/extensions/flags/js/src/forum/components/FlagsDropdown.js
+++ b/extensions/flags/js/src/forum/components/FlagsDropdown.js
@@ -11,6 +11,9 @@ export default class FlagsDropdown extends NotificationsDropdown {
     super.initAttrs(attrs);
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getMenu() {
     return (
       <div className={'Dropdown-menu ' + this.attrs.menuClassName} onclick={this.menuClick.bind(this)}>
diff --git a/extensions/flags/js/src/forum/components/FlagsPage.js b/extensions/flags/js/src/forum/components/FlagsPage.js
index 6e07ef555..9c54c52b1 100644
--- a/extensions/flags/js/src/forum/components/FlagsPage.js
+++ b/extensions/flags/js/src/forum/components/FlagsPage.js
@@ -18,6 +18,9 @@ export default class FlagsPage extends Page {
     this.bodyClass = 'App--flags';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <div className="FlagsPage">
diff --git a/extensions/package-manager/js/src/admin/components/Updater.tsx b/extensions/package-manager/js/src/admin/components/Updater.tsx
index 4acbfb860..ec6723ac4 100755
--- a/extensions/package-manager/js/src/admin/components/Updater.tsx
+++ b/extensions/package-manager/js/src/admin/components/Updater.tsx
@@ -64,7 +64,7 @@ export default class Updater<Attrs> extends Component<Attrs> {
     super.oninit(vnode);
   }
 
-  view() {
+  view(): Mithril.Children {
     const extensions = this.getExtensionUpdates();
     let coreUpdate: UpdatedPackage | undefined = this.getCoreUpdate();
     let core: any;
diff --git a/extensions/package-manager/js/src/admin/components/WhyNotModal.tsx b/extensions/package-manager/js/src/admin/components/WhyNotModal.tsx
index 352cc769a..8f0b39703 100644
--- a/extensions/package-manager/js/src/admin/components/WhyNotModal.tsx
+++ b/extensions/package-manager/js/src/admin/components/WhyNotModal.tsx
@@ -26,7 +26,7 @@ export default class WhyNotModal<Attrs extends WhyNotModalAttrs = WhyNotModalAtt
     this.requestWhyNot();
   }
 
-  content() {
+  content(): Mithril.Children {
     return <div className="Modal-body">{this.loading ? <LoadingIndicator /> : <pre className="WhyNotModal-contents">{this.whyNot}</pre>}</div>;
   }
 
diff --git a/extensions/statistics/js/src/admin/components/StatisticsWidget.js b/extensions/statistics/js/src/admin/components/StatisticsWidget.js
index f9ac9fb8a..8ae954b28 100644
--- a/extensions/statistics/js/src/admin/components/StatisticsWidget.js
+++ b/extensions/statistics/js/src/admin/components/StatisticsWidget.js
@@ -46,6 +46,9 @@ export default class StatisticsWidget extends DashboardWidget {
     return 'StatisticsWidget';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     const thisPeriod = this.periods[this.selectedPeriod];
 
diff --git a/extensions/tags/js/src/admin/components/EditTagModal.tsx b/extensions/tags/js/src/admin/components/EditTagModal.tsx
index f33025ed7..42c6be56b 100644
--- a/extensions/tags/js/src/admin/components/EditTagModal.tsx
+++ b/extensions/tags/js/src/admin/components/EditTagModal.tsx
@@ -7,7 +7,7 @@ import { slug } from 'flarum/common/utils/string';
 import Stream from 'flarum/common/utils/Stream';
 
 import tagLabel from '../../common/helpers/tagLabel';
-import type Mithril from 'mithril';
+import Mithril from 'mithril';
 import type Tag from '../../common/models/Tag';
 import extractText from 'flarum/common/utils/extractText';
 import { ModelIdentifier } from 'flarum/common/Model';
@@ -50,13 +50,13 @@ export default class EditTagModal extends Modal<EditTagModalAttrs> {
     return 'EditTagModal Modal--small';
   }
 
-  title() {
+  title(): Mithril.Children {
     return this.name()
-      ? tagLabel(app.store.createRecord('tags', { attributes: this.submitData() }))
+      ? tagLabel(app.store.createRecord<Tag>('tags', { attributes: this.submitData() }))
       : app.translator.trans('flarum-tags.admin.edit_tag.title');
   }
 
-  content() {
+  content(): Mithril.Children {
     return (
       <div className="Modal-body">
         <div className="Form">
@@ -67,7 +67,7 @@ export default class EditTagModal extends Modal<EditTagModalAttrs> {
   }
 
   fields() {
-    const items = new ItemList();
+    const items = new ItemList<Mithril.Children>();
 
     items.add('name', <div className="Form-group">
       <label>{app.translator.trans('flarum-tags.admin.edit_tag.name_label')}</label>
diff --git a/extensions/tags/js/src/admin/components/TagsPage.js b/extensions/tags/js/src/admin/components/TagsPage.js
index 142fd2193..52140e9ea 100644
--- a/extensions/tags/js/src/admin/components/TagsPage.js
+++ b/extensions/tags/js/src/admin/components/TagsPage.js
@@ -51,6 +51,9 @@ export default class TagsPage extends ExtensionPage {
     });
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.loading) {
       return <LoadingIndicator />;
@@ -63,7 +66,7 @@ export default class TagsPage extends ExtensionPage {
     const maxSecondaryTags = this.setting('flarum-tags.max_secondary_tags', 0);
 
     const tags = sortTags(app.store.all('tags').filter(tag => !tag.parent()));
-    
+
     return (
       <div className="TagsContent">
         <div className="TagsContent-list">
diff --git a/extensions/tags/js/src/common/helpers/tagIcon.js b/extensions/tags/js/src/common/helpers/tagIcon.tsx
similarity index 67%
rename from extensions/tags/js/src/common/helpers/tagIcon.js
rename to extensions/tags/js/src/common/helpers/tagIcon.tsx
index c15430a50..a1aec6007 100644
--- a/extensions/tags/js/src/common/helpers/tagIcon.js
+++ b/extensions/tags/js/src/common/helpers/tagIcon.tsx
@@ -1,6 +1,9 @@
+import { ComponentAttrs } from 'flarum/common/Component';
 import classList from 'flarum/common/utils/classList';
+import Tag from '../models/Tag';
+import type Mithril from 'mithril';
 
-export default function tagIcon(tag, attrs = {}, settings = {}) {
+export default function tagIcon(tag: Tag, attrs: ComponentAttrs = {}, settings: {useColor?: boolean} = {}): Mithril.Children {
   const hasIcon = tag && tag.icon();
   const { useColor = true } = settings;
 
diff --git a/extensions/tags/js/src/common/helpers/tagLabel.js b/extensions/tags/js/src/common/helpers/tagLabel.tsx
similarity index 66%
rename from extensions/tags/js/src/common/helpers/tagLabel.js
rename to extensions/tags/js/src/common/helpers/tagLabel.tsx
index 8b5df2ae0..3e73fa458 100644
--- a/extensions/tags/js/src/common/helpers/tagLabel.js
+++ b/extensions/tags/js/src/common/helpers/tagLabel.tsx
@@ -1,8 +1,13 @@
+import app from 'flarum/common/app';
+
 import extract from 'flarum/common/utils/extract';
 import Link from 'flarum/common/components/Link';
 import tagIcon from './tagIcon';
+import Tag from '../models/Tag';
+import type { ComponentAttrs } from 'flarum/common/Component';
+import type Mithril from 'mithril';
 
-export default function tagLabel(tag, attrs = {}) {
+export default function tagLabel(tag?: Tag, attrs: ComponentAttrs = {}): Mithril.Children {
   attrs.style = attrs.style || {};
   attrs.className = 'TagLabel ' + (attrs.className || '');
 
@@ -28,11 +33,15 @@ export default function tagLabel(tag, attrs = {}) {
     attrs.className += ' untagged';
   }
 
-  return (
-    m((link ? Link : 'span'), attrs,
-      <span className="TagLabel-text">
+  const children = (
+    <span className="TagLabel-text">
         {tag && tag.icon() && tagIcon(tag, {}, {useColor: false})} {tagText}
       </span>
-    )
   );
+
+  if (link) {
+    return <Link {...attrs}>{children}</Link>
+  }
+
+  return <span {...attrs}>{children}</span>;
 }
diff --git a/extensions/tags/js/src/common/helpers/tagsLabel.js b/extensions/tags/js/src/common/helpers/tagsLabel.tsx
similarity index 63%
rename from extensions/tags/js/src/common/helpers/tagsLabel.js
rename to extensions/tags/js/src/common/helpers/tagsLabel.tsx
index 370e66cd1..2477301f7 100644
--- a/extensions/tags/js/src/common/helpers/tagsLabel.js
+++ b/extensions/tags/js/src/common/helpers/tagsLabel.tsx
@@ -1,15 +1,18 @@
 import extract from 'flarum/common/utils/extract';
 import tagLabel from './tagLabel';
 import sortTags from '../utils/sortTags';
+import Tag from '../models/Tag';
+import type { ComponentAttrs } from 'flarum/common/Component';
+import type Mithril from 'mithril';
 
-export default function tagsLabel(tags, attrs = {}) {
+export default function tagsLabel(tags: Tag[], attrs: ComponentAttrs = {}): Mithril.Children {
   const children = [];
   const link = extract(attrs, 'link');
 
   attrs.className = 'TagsLabel ' + (attrs.className || '');
 
   if (tags) {
-    sortTags(tags).forEach(tag => {
+    sortTags(tags).forEach((tag: Tag) => {
       if (tag || tags.length === 1) {
         children.push(tagLabel(tag, {link}));
       }
diff --git a/extensions/tags/js/src/forum/components/TagDiscussionModal.tsx b/extensions/tags/js/src/forum/components/TagDiscussionModal.tsx
index 814522e8e..17b7cf64a 100644
--- a/extensions/tags/js/src/forum/components/TagDiscussionModal.tsx
+++ b/extensions/tags/js/src/forum/components/TagDiscussionModal.tsx
@@ -139,6 +139,9 @@ export default class TagDiscussionModal extends Modal<TagDiscussionModalAttrs> {
     return '';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.tagsLoading || !this.tags) {
       return <LoadingIndicator />;
diff --git a/extensions/tags/js/src/forum/components/TagHero.js b/extensions/tags/js/src/forum/components/TagHero.js
index bd2b899a0..581588339 100644
--- a/extensions/tags/js/src/forum/components/TagHero.js
+++ b/extensions/tags/js/src/forum/components/TagHero.js
@@ -2,6 +2,9 @@ import Component from 'flarum/common/Component';
 import tagIcon from '../../common/helpers/tagIcon';
 
 export default class TagHero extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const tag = this.attrs.model;
     const color = tag.color();
diff --git a/extensions/tags/js/src/forum/components/TagLinkButton.js b/extensions/tags/js/src/forum/components/TagLinkButton.js
index 9fb2f8b14..911ad9379 100644
--- a/extensions/tags/js/src/forum/components/TagLinkButton.js
+++ b/extensions/tags/js/src/forum/components/TagLinkButton.js
@@ -4,6 +4,9 @@ import classList from 'flarum/common/utils/classList';
 import tagIcon from '../../common/helpers/tagIcon';
 
 export default class TagLinkButton extends LinkButton {
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     const tag = this.attrs.model;
     const active = this.constructor.isActive(this.attrs);
diff --git a/extensions/tags/js/src/forum/components/TagsPage.js b/extensions/tags/js/src/forum/components/TagsPage.js
index c3bc1cb39..00313a694 100755
--- a/extensions/tags/js/src/forum/components/TagsPage.js
+++ b/extensions/tags/js/src/forum/components/TagsPage.js
@@ -35,6 +35,9 @@ export default class TagsPage extends Page {
     });
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     if (this.loading) {
       return <LoadingIndicator />;
diff --git a/extensions/tags/js/src/forum/components/ToggleButton.js b/extensions/tags/js/src/forum/components/ToggleButton.js
index cbf4904ff..68a748ee5 100644
--- a/extensions/tags/js/src/forum/components/ToggleButton.js
+++ b/extensions/tags/js/src/forum/components/ToggleButton.js
@@ -6,6 +6,9 @@ import classList from 'flarum/common/utils/classList';
  * @TODO move to core
  */
 export default class ToggleButton extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     const { className, isToggled, ...attrs } = this.attrs;
     const icon = isToggled ? 'far fa-check-circle' : 'far fa-circle';
diff --git a/framework/core/js/src/admin/components/AdminHeader.js b/framework/core/js/src/admin/components/AdminHeader.tsx
similarity index 52%
rename from framework/core/js/src/admin/components/AdminHeader.js
rename to framework/core/js/src/admin/components/AdminHeader.tsx
index 5472a8064..80c6e83fd 100644
--- a/framework/core/js/src/admin/components/AdminHeader.js
+++ b/framework/core/js/src/admin/components/AdminHeader.tsx
@@ -1,9 +1,15 @@
-import Component from '../../common/Component';
+import Component, { ComponentAttrs } from '../../common/Component';
 import classList from '../../common/utils/classList';
 import icon from '../../common/helpers/icon';
+import type Mithril from 'mithril';
 
-export default class AdminHeader extends Component {
-  view(vnode) {
+export interface IAdminHeaderAttrs extends ComponentAttrs {
+  icon: string;
+  description: string;
+}
+
+export default class AdminHeader<CustomAttrs extends IAdminHeaderAttrs = IAdminHeaderAttrs> extends Component<CustomAttrs> {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>): Mithril.Children {
     return [
       <div className={classList(['AdminHeader', this.attrs.className])}>
         <div className="container">
diff --git a/framework/core/js/src/admin/components/AdminNav.js b/framework/core/js/src/admin/components/AdminNav.js
index 506334a0a..b39c1ae96 100644
--- a/framework/core/js/src/admin/components/AdminNav.js
+++ b/framework/core/js/src/admin/components/AdminNav.js
@@ -14,6 +14,9 @@ export default class AdminNav extends Component {
     this.query = Stream('');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <SelectDropdown className="AdminNav App-titleControl AdminNav-Main" buttonClassName="Button">
diff --git a/framework/core/js/src/admin/components/AppearancePage.js b/framework/core/js/src/admin/components/AppearancePage.js
index 0550f3841..d983254f0 100644
--- a/framework/core/js/src/admin/components/AppearancePage.js
+++ b/framework/core/js/src/admin/components/AppearancePage.js
@@ -17,6 +17,9 @@ export default class AppearancePage extends AdminPage {
     };
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return [
       <div className="Form">
diff --git a/framework/core/js/src/admin/components/BasicsPage.js b/framework/core/js/src/admin/components/BasicsPage.js
index 658eaca68..af427282a 100644
--- a/framework/core/js/src/admin/components/BasicsPage.js
+++ b/framework/core/js/src/admin/components/BasicsPage.js
@@ -38,6 +38,9 @@ export default class BasicsPage extends AdminPage {
     };
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return [
       <div className="Form">
diff --git a/framework/core/js/src/admin/components/EditCustomCssModal.js b/framework/core/js/src/admin/components/EditCustomCssModal.js
index 432961074..068cbe7d0 100644
--- a/framework/core/js/src/admin/components/EditCustomCssModal.js
+++ b/framework/core/js/src/admin/components/EditCustomCssModal.js
@@ -10,6 +10,9 @@ export default class EditCustomCssModal extends SettingsModal {
     return app.translator.trans('core.admin.edit_css.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   form() {
     return [
       <p>
diff --git a/framework/core/js/src/admin/components/EditCustomFooterModal.js b/framework/core/js/src/admin/components/EditCustomFooterModal.js
index 97188ec83..bb5971b19 100644
--- a/framework/core/js/src/admin/components/EditCustomFooterModal.js
+++ b/framework/core/js/src/admin/components/EditCustomFooterModal.js
@@ -10,6 +10,9 @@ export default class EditCustomFooterModal extends SettingsModal {
     return app.translator.trans('core.admin.edit_footer.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   form() {
     return [
       <p>{app.translator.trans('core.admin.edit_footer.customize_text')}</p>,
diff --git a/framework/core/js/src/admin/components/EditCustomHeaderModal.js b/framework/core/js/src/admin/components/EditCustomHeaderModal.js
index 4da7afe9d..b30af60bf 100644
--- a/framework/core/js/src/admin/components/EditCustomHeaderModal.js
+++ b/framework/core/js/src/admin/components/EditCustomHeaderModal.js
@@ -10,6 +10,9 @@ export default class EditCustomHeaderModal extends SettingsModal {
     return app.translator.trans('core.admin.edit_header.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   form() {
     return [
       <p>{app.translator.trans('core.admin.edit_header.customize_text')}</p>,
diff --git a/framework/core/js/src/admin/components/EditGroupModal.js b/framework/core/js/src/admin/components/EditGroupModal.js
index a347a5995..654d147dd 100644
--- a/framework/core/js/src/admin/components/EditGroupModal.js
+++ b/framework/core/js/src/admin/components/EditGroupModal.js
@@ -41,6 +41,9 @@ export default class EditGroupModal extends Modal {
     ];
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return (
       <div className="Modal-body">
diff --git a/framework/core/js/src/admin/components/ExtensionPage.tsx b/framework/core/js/src/admin/components/ExtensionPage.tsx
index fa6acccaa..af4a1fa9d 100644
--- a/framework/core/js/src/admin/components/ExtensionPage.tsx
+++ b/framework/core/js/src/admin/components/ExtensionPage.tsx
@@ -15,7 +15,7 @@ import ReadmeModal from './ReadmeModal';
 import RequestError from '../../common/utils/RequestError';
 import { Extension } from '../AdminApplication';
 import { IPageAttrs } from '../../common/components/Page';
-import type Mithril from 'mithril';
+import Mithril from 'mithril';
 import extractText from '../../common/utils/extractText';
 
 export interface ExtensionPageAttrs extends IPageAttrs {
@@ -54,7 +54,7 @@ export default class ExtensionPage<Attrs extends ExtensionPageAttrs = ExtensionP
     return this.extension.id + '-Page';
   }
 
-  view(vnode: Mithril.VnodeDOM<Attrs, this>) {
+  view(vnode: Mithril.VnodeDOM<Attrs, this>): Mithril.Children {
     if (!this.extension) return null;
 
     return (
@@ -71,7 +71,7 @@ export default class ExtensionPage<Attrs extends ExtensionPageAttrs = ExtensionP
     );
   }
 
-  header() {
+  header(): Mithril.Children {
     const isEnabled = this.isEnabled();
 
     return [
@@ -106,8 +106,8 @@ export default class ExtensionPage<Attrs extends ExtensionPageAttrs = ExtensionP
     ];
   }
 
-  sections(vnode: Mithril.VnodeDOM<Attrs, this>) {
-    const items = new ItemList();
+  sections(vnode: Mithril.VnodeDOM<Attrs, this>): ItemList<Mithril.Children> {
+    const items = new ItemList<Mithril.Children>();
 
     items.add('content', this.content(vnode));
 
@@ -131,7 +131,7 @@ export default class ExtensionPage<Attrs extends ExtensionPageAttrs = ExtensionP
     return items;
   }
 
-  content(vnode: Mithril.VnodeDOM<Attrs, this>) {
+  content(vnode: Mithril.VnodeDOM<Attrs, this>): Mithril.Children {
     const settings = app.extensionData.getSettings(this.extension.id);
 
     return (
@@ -150,7 +150,7 @@ export default class ExtensionPage<Attrs extends ExtensionPageAttrs = ExtensionP
     );
   }
 
-  topItems() {
+  topItems(): ItemList<Mithril.Children> {
     const items = new ItemList<Mithril.Children>();
 
     items.add('version', <span className="ExtensionVersion">{this.extension.version}</span>);
diff --git a/framework/core/js/src/admin/components/ExtensionsWidget.js b/framework/core/js/src/admin/components/ExtensionsWidget.js
index 0647f272f..ae61338f6 100644
--- a/framework/core/js/src/admin/components/ExtensionsWidget.js
+++ b/framework/core/js/src/admin/components/ExtensionsWidget.js
@@ -16,6 +16,9 @@ export default class ExtensionsWidget extends DashboardWidget {
     return 'ExtensionsWidget';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     const categories = app.extensionCategories;
 
@@ -26,6 +29,9 @@ export default class ExtensionsWidget extends DashboardWidget {
     );
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   extensionCategory(category) {
     return (
       <div className="ExtensionList-Category">
@@ -35,6 +41,9 @@ export default class ExtensionsWidget extends DashboardWidget {
     );
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   extensionWidget(extension) {
     return (
       <li className={'ExtensionListItem ' + (!isExtensionEnabled(extension.id) ? 'disabled' : '')}>
diff --git a/framework/core/js/src/admin/components/HeaderPrimary.js b/framework/core/js/src/admin/components/HeaderPrimary.js
index 8246761a3..95a2bcbd0 100644
--- a/framework/core/js/src/admin/components/HeaderPrimary.js
+++ b/framework/core/js/src/admin/components/HeaderPrimary.js
@@ -7,6 +7,9 @@ import listItems from '../../common/helpers/listItems';
  * default skin, these are shown just to the right of the forum title.
  */
 export default class HeaderPrimary extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return <ul className="Header-controls">{listItems(this.items().toArray())}</ul>;
   }
diff --git a/framework/core/js/src/admin/components/HeaderSecondary.js b/framework/core/js/src/admin/components/HeaderSecondary.js
index 255815be2..8dcbfca06 100644
--- a/framework/core/js/src/admin/components/HeaderSecondary.js
+++ b/framework/core/js/src/admin/components/HeaderSecondary.js
@@ -9,6 +9,9 @@ import listItems from '../../common/helpers/listItems';
  * The `HeaderSecondary` component displays secondary header controls.
  */
 export default class HeaderSecondary extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return <ul className="Header-controls">{listItems(this.items().toArray())}</ul>;
   }
diff --git a/framework/core/js/src/admin/components/MailPage.js b/framework/core/js/src/admin/components/MailPage.js
index 9ff161ee2..cc7184e76 100644
--- a/framework/core/js/src/admin/components/MailPage.js
+++ b/framework/core/js/src/admin/components/MailPage.js
@@ -42,6 +42,9 @@ export default class MailPage extends AdminPage {
       });
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.loading) {
       return <LoadingIndicator />;
diff --git a/framework/core/js/src/admin/components/PermissionGrid.tsx b/framework/core/js/src/admin/components/PermissionGrid.tsx
index 37741ff29..c2be231b0 100644
--- a/framework/core/js/src/admin/components/PermissionGrid.tsx
+++ b/framework/core/js/src/admin/components/PermissionGrid.tsx
@@ -33,7 +33,7 @@ export interface ScopeItem {
 export interface IPermissionGridAttrs extends ComponentAttrs {}
 
 export default class PermissionGrid<CustomAttrs extends IPermissionGridAttrs = IPermissionGridAttrs> extends Component<CustomAttrs> {
-  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>): Mithril.Children {
     const scopes = this.scopeItems().toArray();
 
     const permissionCells = (permission: PermissionGridEntry | { children: PermissionGridEntry[] }) => {
diff --git a/framework/core/js/src/admin/components/PermissionsPage.js b/framework/core/js/src/admin/components/PermissionsPage.js
index c985fa35e..f2d0cfe00 100644
--- a/framework/core/js/src/admin/components/PermissionsPage.js
+++ b/framework/core/js/src/admin/components/PermissionsPage.js
@@ -16,6 +16,9 @@ export default class PermissionsPage extends AdminPage {
     };
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return [
       <div className="PermissionsPage-groups">
diff --git a/framework/core/js/src/admin/components/ReadmeModal.tsx b/framework/core/js/src/admin/components/ReadmeModal.tsx
index e2cc9f0bc..96a906a02 100644
--- a/framework/core/js/src/admin/components/ReadmeModal.tsx
+++ b/framework/core/js/src/admin/components/ReadmeModal.tsx
@@ -38,7 +38,7 @@ export default class ReadmeModal<CustomAttrs extends IReadmeModalAttrs = IReadme
     });
   }
 
-  content() {
+  content(): Mithril.Children {
     const text = app.translator.trans('core.admin.extension.readme.no_readme');
 
     return (
diff --git a/framework/core/js/src/admin/components/SessionDropdown.js b/framework/core/js/src/admin/components/SessionDropdown.js
index 9e28775b4..ae0383855 100644
--- a/framework/core/js/src/admin/components/SessionDropdown.js
+++ b/framework/core/js/src/admin/components/SessionDropdown.js
@@ -18,10 +18,16 @@ export default class SessionDropdown extends Dropdown {
     attrs.menuClassName = 'Dropdown-menu--right';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     return super.view({ ...vnode, children: this.items().toArray() });
   }
 
+  /**
+   * @returns {import('mithril').Children}
+   */
   getButtonContent() {
     const user = app.session.user;
 
diff --git a/framework/core/js/src/admin/components/SettingsModal.js b/framework/core/js/src/admin/components/SettingsModal.js
index e108c78ae..45995499a 100644
--- a/framework/core/js/src/admin/components/SettingsModal.js
+++ b/framework/core/js/src/admin/components/SettingsModal.js
@@ -16,6 +16,9 @@ export default class SettingsModal extends Modal {
     return '';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return (
       <div className="Modal-body">
@@ -28,6 +31,9 @@ export default class SettingsModal extends Modal {
     );
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   submitButton() {
     return (
       <Button type="submit" className="Button Button--primary" loading={this.loading} disabled={!this.changed()}>
diff --git a/framework/core/js/src/admin/components/StatusWidget.js b/framework/core/js/src/admin/components/StatusWidget.js
index 7ced35b47..8d415c77b 100644
--- a/framework/core/js/src/admin/components/StatusWidget.js
+++ b/framework/core/js/src/admin/components/StatusWidget.js
@@ -11,6 +11,9 @@ export default class StatusWidget extends DashboardWidget {
     return 'StatusWidget';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return <ul>{listItems(this.items().toArray())}</ul>;
   }
diff --git a/framework/core/js/src/admin/components/UploadImageButton.js b/framework/core/js/src/admin/components/UploadImageButton.js
index e62454078..ab8ea4e28 100644
--- a/framework/core/js/src/admin/components/UploadImageButton.js
+++ b/framework/core/js/src/admin/components/UploadImageButton.js
@@ -4,6 +4,9 @@ import Button from '../../common/components/Button';
 export default class UploadImageButton extends Button {
   loading = false;
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     this.attrs.loading = this.loading;
     this.attrs.className = (this.attrs.className || '') + ' Button';
diff --git a/framework/core/js/src/admin/components/UserListPage.tsx b/framework/core/js/src/admin/components/UserListPage.tsx
index 3502a24f9..b26a41390 100644
--- a/framework/core/js/src/admin/components/UserListPage.tsx
+++ b/framework/core/js/src/admin/components/UserListPage.tsx
@@ -77,7 +77,7 @@ export default class UserListPage extends AdminPage {
   /**
    * Component to render.
    */
-  content() {
+  content(): Mithril.Children {
     if (typeof this.pageData === 'undefined') {
       this.loadPage(0);
 
diff --git a/framework/core/js/src/common/components/Alert.tsx b/framework/core/js/src/common/components/Alert.tsx
index d9601b04e..09a0a1ea3 100644
--- a/framework/core/js/src/common/components/Alert.tsx
+++ b/framework/core/js/src/common/components/Alert.tsx
@@ -22,7 +22,7 @@ export interface AlertAttrs extends ComponentAttrs {
  * some controls, and may be dismissible.
  */
 export default class Alert<T extends AlertAttrs = AlertAttrs> extends Component<T> {
-  view(vnode: Mithril.VnodeDOM<T, this>) {
+  view(vnode: Mithril.VnodeDOM<T, this>): Mithril.Children {
     const attrs = Object.assign({}, this.attrs);
 
     const type = extract(attrs, 'type');
diff --git a/framework/core/js/src/common/components/AlertManager.js b/framework/core/js/src/common/components/AlertManager.js
deleted file mode 100644
index 90aa2e93d..000000000
--- a/framework/core/js/src/common/components/AlertManager.js
+++ /dev/null
@@ -1,31 +0,0 @@
-import Component from '../Component';
-
-/**
- * The `AlertManager` component provides an area in which `Alert` components can
- * be shown and dismissed.
- */
-export default class AlertManager extends Component {
-  oninit(vnode) {
-    super.oninit(vnode);
-
-    this.state = this.attrs.state;
-  }
-
-  view() {
-    return (
-      <div class="AlertManager">
-        {Object.entries(this.state.getActiveAlerts()).map(([key, alert]) => {
-          const urgent = alert.attrs.type === 'error';
-
-          return (
-            <div class="AlertManager-alert" role="alert" aria-live={urgent ? 'assertive' : 'polite'}>
-              <alert.componentClass {...alert.attrs} ondismiss={this.state.dismiss.bind(this.state, key)}>
-                {alert.children}
-              </alert.componentClass>
-            </div>
-          );
-        })}
-      </div>
-    );
-  }
-}
diff --git a/framework/core/js/src/common/components/AlertManager.tsx b/framework/core/js/src/common/components/AlertManager.tsx
new file mode 100644
index 000000000..4e094bf13
--- /dev/null
+++ b/framework/core/js/src/common/components/AlertManager.tsx
@@ -0,0 +1,39 @@
+import Mithril from 'mithril';
+import Component, { ComponentAttrs } from '../Component';
+import type AlertManagerState from '../states/AlertManagerState';
+
+export interface IAlertManagerAttrs extends ComponentAttrs {
+  state: AlertManagerState;
+}
+
+/**
+ * The `AlertManager` component provides an area in which `Alert` components can
+ * be shown and dismissed.
+ */
+export default class AlertManager<CustomAttrs extends IAlertManagerAttrs = IAlertManagerAttrs> extends Component<CustomAttrs> {
+  alertsState!: AlertManagerState;
+
+  oninit(vnode: Mithril.Vnode<CustomAttrs, this>) {
+    super.oninit(vnode);
+
+    this.alertsState = this.attrs.state;
+  }
+
+  view(): Mithril.Children {
+    return (
+      <div class="AlertManager">
+        {Object.entries(this.alertsState.getActiveAlerts()).map(([key, alert]) => {
+          const urgent = alert.attrs.type === 'error';
+
+          return (
+            <div class="AlertManager-alert" role="alert" aria-live={urgent ? 'assertive' : 'polite'}>
+              <alert.componentClass {...alert.attrs} ondismiss={this.alertsState.dismiss.bind(this.alertsState, parseInt(key))}>
+                {alert.children}
+              </alert.componentClass>
+            </div>
+          );
+        })}
+      </div>
+    );
+  }
+}
diff --git a/framework/core/js/src/common/components/Badge.js b/framework/core/js/src/common/components/Badge.js
index 39f63e16b..27127548b 100644
--- a/framework/core/js/src/common/components/Badge.js
+++ b/framework/core/js/src/common/components/Badge.js
@@ -17,6 +17,9 @@ import classList from '../utils/classList';
  * All other attrs will be assigned as attributes on the badge element.
  */
 export default class Badge extends Component {
+  /**
+   * @returns {import('mithril').Children}
+   */
   view() {
     const { type, icon: iconName, label, color, style = {}, ...attrs } = this.attrs;
 
diff --git a/framework/core/js/src/common/components/Button.tsx b/framework/core/js/src/common/components/Button.tsx
index 86e9ce001..07ed32e7b 100644
--- a/framework/core/js/src/common/components/Button.tsx
+++ b/framework/core/js/src/common/components/Button.tsx
@@ -67,7 +67,7 @@ export interface IButtonAttrs extends ComponentAttrs {
  * styles can be applied by providing `className="Button"` to the Button component.
  */
 export default class Button<CustomAttrs extends IButtonAttrs = IButtonAttrs> extends Component<CustomAttrs> {
-  view(vnode: Mithril.VnodeDOM<CustomAttrs, this>) {
+  view(vnode: Mithril.VnodeDOM<CustomAttrs, this>): Mithril.Children {
     let { type, title, 'aria-label': ariaLabel, icon: iconName, disabled, loading, className, class: _class, ...attrs } = this.attrs;
 
     // If no `type` attr provided, set to "button"
diff --git a/framework/core/js/src/common/components/Checkbox.js b/framework/core/js/src/common/components/Checkbox.js
index bc7ed5db1..3b531de84 100644
--- a/framework/core/js/src/common/components/Checkbox.js
+++ b/framework/core/js/src/common/components/Checkbox.js
@@ -17,6 +17,9 @@ import withAttr from '../utils/withAttr';
  * - `children` A text label to display next to the checkbox.
  */
 export default class Checkbox extends Component {
+  /**
+   * @returns {import('mithril').Children}
+   */
   view(vnode) {
     // Sometimes, false is stored in the DB as '0'. This is a temporary
     // conversion layer until a more robust settings encoding is introduced
diff --git a/framework/core/js/src/common/components/ColorPreviewInput.tsx b/framework/core/js/src/common/components/ColorPreviewInput.tsx
index a33944244..50bf719cd 100644
--- a/framework/core/js/src/common/components/ColorPreviewInput.tsx
+++ b/framework/core/js/src/common/components/ColorPreviewInput.tsx
@@ -5,7 +5,7 @@ import classList from '../utils/classList';
 import icon from '../helpers/icon';
 
 export default class ColorPreviewInput extends Component {
-  view(vnode: Mithril.Vnode<ComponentAttrs, this>) {
+  view(vnode: Mithril.Vnode<ComponentAttrs, this>): Mithril.Children {
     const { className, id, ...attrs } = this.attrs;
 
     attrs.type ||= 'text';
diff --git a/framework/core/js/src/common/components/Dropdown.js b/framework/core/js/src/common/components/Dropdown.js
index 47c63b3a3..c99abdc65 100644
--- a/framework/core/js/src/common/components/Dropdown.js
+++ b/framework/core/js/src/common/components/Dropdown.js
@@ -36,6 +36,9 @@ export default class Dropdown extends Component {
     this.showing = false;
   }
 
+  /**
+   * @returns {import('mithril').Children}
+   */
   view(vnode) {
     const items = vnode.children ? listItems(vnode.children) : [];
     const renderItems = this.attrs.lazyDraw ? this.showing : true;
@@ -134,6 +137,9 @@ export default class Dropdown extends Component {
     ];
   }
 
+  /**
+   * @returns {import('mithril').Children}
+   */
   getMenu(items) {
     return <ul className={'Dropdown-menu dropdown-menu ' + this.attrs.menuClassName}>{items}</ul>;
   }
diff --git a/framework/core/js/src/common/components/EditUserModal.tsx b/framework/core/js/src/common/components/EditUserModal.tsx
index f876acb37..c2de1f477 100644
--- a/framework/core/js/src/common/components/EditUserModal.tsx
+++ b/framework/core/js/src/common/components/EditUserModal.tsx
@@ -6,7 +6,7 @@ import Group from '../models/Group';
 import extractText from '../utils/extractText';
 import ItemList from '../utils/ItemList';
 import Stream from '../utils/Stream';
-import type Mithril from 'mithril';
+import Mithril from 'mithril';
 import type User from '../models/User';
 import type { SaveAttributes, SaveRelationships } from '../Model';
 
@@ -45,11 +45,11 @@ export default class EditUserModal<CustomAttrs extends IEditUserModalAttrs = IEd
     return 'EditUserModal Modal--small';
   }
 
-  title() {
+  title(): Mithril.Children {
     return app.translator.trans('core.lib.edit_user.title');
   }
 
-  content() {
+  content(): Mithril.Children {
     const fields = this.fields().toArray();
     return (
       <div className="Modal-body">
@@ -58,8 +58,8 @@ export default class EditUserModal<CustomAttrs extends IEditUserModalAttrs = IEd
     );
   }
 
-  fields() {
-    const items = new ItemList();
+  fields(): ItemList<Mithril.Children> {
+    const items = new ItemList<Mithril.Children>();
 
     if (this.attrs.user.canEditCredentials()) {
       items.add(
diff --git a/framework/core/js/src/common/components/FieldSet.js b/framework/core/js/src/common/components/FieldSet.js
index 9b829fbe0..ee75d07eb 100644
--- a/framework/core/js/src/common/components/FieldSet.js
+++ b/framework/core/js/src/common/components/FieldSet.js
@@ -11,6 +11,9 @@ import listItems from '../helpers/listItems';
  * The children should be an array of items to show in the fieldset.
  */
 export default class FieldSet extends Component {
+  /**
+   * @returns {import('mithril').Children}
+   */
   view(vnode) {
     return (
       <fieldset className={this.attrs.className}>
diff --git a/framework/core/js/src/common/components/Link.js b/framework/core/js/src/common/components/Link.js
index deca94683..05d28cf50 100644
--- a/framework/core/js/src/common/components/Link.js
+++ b/framework/core/js/src/common/components/Link.js
@@ -10,6 +10,9 @@ import extract from '../utils/extract';
  * `true` for the link to be external.
  */
 export default class Link extends Component {
+  /**
+   * @returns {import('mithril').Children}
+   */
   view(vnode) {
     let { options = {}, ...attrs } = vnode.attrs;
 
diff --git a/framework/core/js/src/common/components/LoadingIndicator.tsx b/framework/core/js/src/common/components/LoadingIndicator.tsx
index 66330b6bb..119c58025 100644
--- a/framework/core/js/src/common/components/LoadingIndicator.tsx
+++ b/framework/core/js/src/common/components/LoadingIndicator.tsx
@@ -1,6 +1,7 @@
 import app from '../../common/app';
 import Component, { ComponentAttrs } from '../Component';
 import classList from '../utils/classList';
+import type Mithril from 'mithril';
 
 export interface LoadingIndicatorAttrs extends ComponentAttrs {
   /**
@@ -55,7 +56,7 @@ export interface LoadingIndicatorAttrs extends ComponentAttrs {
  * All other attrs will be assigned as attributes on the DOM element.
  */
 export default class LoadingIndicator extends Component<LoadingIndicatorAttrs> {
-  view() {
+  view(): Mithril.Children {
     const { display = 'block', size = 'medium', containerClassName, className, ...attrs } = this.attrs;
 
     const completeClassName = classList('LoadingIndicator', className);
diff --git a/framework/core/js/src/common/components/Modal.tsx b/framework/core/js/src/common/components/Modal.tsx
index b8656860d..cf3a2c542 100644
--- a/framework/core/js/src/common/components/Modal.tsx
+++ b/framework/core/js/src/common/components/Modal.tsx
@@ -81,7 +81,7 @@ export default abstract class Modal<ModalAttrs extends IInternalModalAttrs = IIn
   /**
    * @todo split into FormModal and Modal in 2.0
    */
-  view() {
+  view(): Mithril.Children {
     if (this.alertAttrs) {
       this.alertAttrs.dismissible = false;
     }
diff --git a/framework/core/js/src/common/components/Navigation.js b/framework/core/js/src/common/components/Navigation.js
index 157d07538..042c3c80f 100644
--- a/framework/core/js/src/common/components/Navigation.js
+++ b/framework/core/js/src/common/components/Navigation.js
@@ -19,6 +19,9 @@ import LinkButton from './LinkButton';
  *   there is no more history to pop.
  */
 export default class Navigation extends Component {
+  /**
+   * @returns {import('mithril').Children}
+   */
   view() {
     const { history, pane } = app;
 
diff --git a/framework/core/js/src/common/components/Placeholder.js b/framework/core/js/src/common/components/Placeholder.js
deleted file mode 100644
index a5d556351..000000000
--- a/framework/core/js/src/common/components/Placeholder.js
+++ /dev/null
@@ -1,19 +0,0 @@
-import Component from '../Component';
-
-/**
- * The `Placeholder` component displays a muted text with some call to action,
- * usually used as an empty state.
- *
- * ### Attrs
- *
- * - `text`
- */
-export default class Placeholder extends Component {
-  view() {
-    return (
-      <div className="Placeholder">
-        <p>{this.attrs.text}</p>
-      </div>
-    );
-  }
-}
diff --git a/framework/core/js/src/common/components/Placeholder.tsx b/framework/core/js/src/common/components/Placeholder.tsx
new file mode 100644
index 000000000..60bb4d8ef
--- /dev/null
+++ b/framework/core/js/src/common/components/Placeholder.tsx
@@ -0,0 +1,20 @@
+import type Mithril from 'mithril';
+import Component, { ComponentAttrs } from '../Component';
+
+interface IPlaceholderAttrs extends ComponentAttrs {
+  text: Mithril.Children;
+}
+
+/**
+ * The `Placeholder` component displays a muted text with some call to action,
+ * usually used as an empty state.
+ */
+export default class Placeholder<CustomAttrs extends IPlaceholderAttrs = IPlaceholderAttrs> extends Component<CustomAttrs> {
+  view(): Mithril.Children {
+    return (
+      <div className="Placeholder">
+        <p>{this.attrs.text}</p>
+      </div>
+    );
+  }
+}
diff --git a/framework/core/js/src/common/components/RequestErrorModal.tsx b/framework/core/js/src/common/components/RequestErrorModal.tsx
index abada7796..64c73f4ca 100644
--- a/framework/core/js/src/common/components/RequestErrorModal.tsx
+++ b/framework/core/js/src/common/components/RequestErrorModal.tsx
@@ -1,3 +1,4 @@
+import type Mithril from 'mithril';
 import type RequestError from '../utils/RequestError';
 import Modal, { IInternalModalAttrs } from './Modal';
 
@@ -15,7 +16,7 @@ export default class RequestErrorModal<CustomAttrs extends IRequestErrorModalAtt
     return this.attrs.error.xhr ? `${this.attrs.error.xhr.status} ${this.attrs.error.xhr.statusText}` : '';
   }
 
-  content() {
+  content(): Mithril.Children {
     const { error, formattedError } = this.attrs;
 
     let responseText;
diff --git a/framework/core/js/src/common/components/Select.js b/framework/core/js/src/common/components/Select.js
index 07866012a..16e9e3da4 100644
--- a/framework/core/js/src/common/components/Select.js
+++ b/framework/core/js/src/common/components/Select.js
@@ -16,6 +16,9 @@ import classList from '../utils/classList';
  * Other attributes are passed directly to the `<select>` element rendered to the DOM.
  */
 export default class Select extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const {
       options,
diff --git a/framework/core/js/src/common/components/SelectDropdown.js b/framework/core/js/src/common/components/SelectDropdown.js
index e7111ffe7..793350d59 100644
--- a/framework/core/js/src/common/components/SelectDropdown.js
+++ b/framework/core/js/src/common/components/SelectDropdown.js
@@ -41,6 +41,9 @@ export default class SelectDropdown extends Dropdown {
     attrs.className += ' Dropdown--select';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getButtonContent(children) {
     const activeChild = children.find(isActive);
     let label = (activeChild && activeChild.children) || this.attrs.defaultLabel;
diff --git a/framework/core/js/src/common/components/Separator.js b/framework/core/js/src/common/components/Separator.tsx
similarity index 53%
rename from framework/core/js/src/common/components/Separator.js
rename to framework/core/js/src/common/components/Separator.tsx
index 1b5ca4911..48ca91f00 100644
--- a/framework/core/js/src/common/components/Separator.js
+++ b/framework/core/js/src/common/components/Separator.tsx
@@ -1,14 +1,13 @@
+import type Mithril from 'mithril';
 import Component from '../Component';
 
 /**
  * The `Separator` component defines a menu separator item.
  */
-class Separator extends Component {
-  view() {
+export default class Separator extends Component {
+  static isListItem = true;
+
+  view(): Mithril.Children {
     return <li className="Dropdown-separator" />;
   }
 }
-
-Separator.isListItem = true;
-
-export default Separator;
diff --git a/framework/core/js/src/common/components/SplitDropdown.js b/framework/core/js/src/common/components/SplitDropdown.js
index fea79e6af..bae9d80b8 100644
--- a/framework/core/js/src/common/components/SplitDropdown.js
+++ b/framework/core/js/src/common/components/SplitDropdown.js
@@ -14,6 +14,9 @@ export default class SplitDropdown extends Dropdown {
     attrs.menuClassName += ' Dropdown-menu--right';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getButton(children) {
     // Make a copy of the attrs of the first child component. We will assign
     // these attrs to a new button, so that it has exactly the same behaviour as
diff --git a/framework/core/js/src/common/components/TextEditor.js b/framework/core/js/src/common/components/TextEditor.js
index c4608ace3..600aa008b 100644
--- a/framework/core/js/src/common/components/TextEditor.js
+++ b/framework/core/js/src/common/components/TextEditor.js
@@ -38,6 +38,9 @@ export default class TextEditor extends Component {
     this.disabled = !!this.attrs.disabled;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <div className="TextEditor">
diff --git a/framework/core/js/src/common/components/TextEditorButton.js b/framework/core/js/src/common/components/TextEditorButton.js
index fa517e627..bd82f756a 100644
--- a/framework/core/js/src/common/components/TextEditorButton.js
+++ b/framework/core/js/src/common/components/TextEditorButton.js
@@ -12,6 +12,9 @@ import Tooltip from './Tooltip';
  * - `title` - Tooltip for the button
  */
 export default class TextEditorButton extends Button {
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     const originalView = super.view(vnode);
 
diff --git a/framework/core/js/src/common/states/AlertManagerState.ts b/framework/core/js/src/common/states/AlertManagerState.ts
index f254ea502..5b3e63624 100644
--- a/framework/core/js/src/common/states/AlertManagerState.ts
+++ b/framework/core/js/src/common/states/AlertManagerState.ts
@@ -13,7 +13,7 @@ export interface AlertState {
 }
 
 export default class AlertManagerState {
-  protected activeAlerts: { [id: number]: AlertState } = {};
+  protected activeAlerts: { [id: AlertIdentifier]: AlertState } = {};
   protected alertId = 0;
 
   getActiveAlerts() {
diff --git a/framework/core/js/src/forum/components/AvatarEditor.js b/framework/core/js/src/forum/components/AvatarEditor.js
index fa2ff1266..84c0e5378 100644
--- a/framework/core/js/src/forum/components/AvatarEditor.js
+++ b/framework/core/js/src/forum/components/AvatarEditor.js
@@ -36,6 +36,9 @@ export default class AvatarEditor extends Component {
     this.isDraggedOver = false;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const user = this.attrs.user;
 
diff --git a/framework/core/js/src/forum/components/ChangeEmailModal.js b/framework/core/js/src/forum/components/ChangeEmailModal.js
index 3d7cb6ef0..62dc0d17c 100644
--- a/framework/core/js/src/forum/components/ChangeEmailModal.js
+++ b/framework/core/js/src/forum/components/ChangeEmailModal.js
@@ -41,6 +41,9 @@ export default class ChangeEmailModal extends Modal {
     return app.translator.trans('core.forum.change_email.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.success) {
       return (
diff --git a/framework/core/js/src/forum/components/ChangePasswordModal.js b/framework/core/js/src/forum/components/ChangePasswordModal.js
index 4c3596e65..53cf25931 100644
--- a/framework/core/js/src/forum/components/ChangePasswordModal.js
+++ b/framework/core/js/src/forum/components/ChangePasswordModal.js
@@ -15,6 +15,9 @@ export default class ChangePasswordModal extends Modal {
     return app.translator.trans('core.forum.change_password.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return (
       <div className="Modal-body">
diff --git a/framework/core/js/src/forum/components/Composer.js b/framework/core/js/src/forum/components/Composer.js
index 71a178976..e98094c61 100644
--- a/framework/core/js/src/forum/components/Composer.js
+++ b/framework/core/js/src/forum/components/Composer.js
@@ -33,6 +33,9 @@ export default class Composer extends Component {
     this.prevPosition = this.state.position;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const body = this.state.body;
     const classes = {
diff --git a/framework/core/js/src/forum/components/ComposerBody.js b/framework/core/js/src/forum/components/ComposerBody.js
index 58df9580e..6f28763d2 100644
--- a/framework/core/js/src/forum/components/ComposerBody.js
+++ b/framework/core/js/src/forum/components/ComposerBody.js
@@ -47,6 +47,9 @@ export default class ComposerBody extends Component {
     this.composer.fields.content(this.attrs.originalContent || '');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <ConfirmDocumentUnload when={this.hasChanges.bind(this)}>
diff --git a/framework/core/js/src/forum/components/ComposerPostPreview.js b/framework/core/js/src/forum/components/ComposerPostPreview.js
index eb06add96..5cd3b7559 100644
--- a/framework/core/js/src/forum/components/ComposerPostPreview.js
+++ b/framework/core/js/src/forum/components/ComposerPostPreview.js
@@ -20,6 +20,9 @@ export default class ComposerPostPreview extends Component {
     attrs.surround = attrs.surround || ((preview) => preview());
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return <div className={this.attrs.className} />;
   }
diff --git a/framework/core/js/src/forum/components/DiscussionHero.js b/framework/core/js/src/forum/components/DiscussionHero.js
index 659cf1a71..f50953295 100644
--- a/framework/core/js/src/forum/components/DiscussionHero.js
+++ b/framework/core/js/src/forum/components/DiscussionHero.js
@@ -10,6 +10,9 @@ import listItems from '../../common/helpers/listItems';
  * - `discussion`
  */
 export default class DiscussionHero extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <header className="Hero DiscussionHero">
diff --git a/framework/core/js/src/forum/components/DiscussionList.js b/framework/core/js/src/forum/components/DiscussionList.js
index 3ba28f807..a30d6e3ad 100644
--- a/framework/core/js/src/forum/components/DiscussionList.js
+++ b/framework/core/js/src/forum/components/DiscussionList.js
@@ -13,6 +13,9 @@ import Placeholder from '../../common/components/Placeholder';
  * - `state` A DiscussionListState object that represents the discussion lists's state.
  */
 export default class DiscussionList extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     /**
      * @type {import('../states/DiscussionListState').default}
diff --git a/framework/core/js/src/forum/components/DiscussionListItem.tsx b/framework/core/js/src/forum/components/DiscussionListItem.tsx
index 20e2946c8..ee44482ec 100644
--- a/framework/core/js/src/forum/components/DiscussionListItem.tsx
+++ b/framework/core/js/src/forum/components/DiscussionListItem.tsx
@@ -62,7 +62,7 @@ export default class DiscussionListItem<CustomAttrs extends IDiscussionListItemA
     };
   }
 
-  view() {
+  view(): Mithril.Children {
     const discussion = this.attrs.discussion;
     const user = discussion.user();
     const isUnread = discussion.isUnread();
@@ -164,10 +164,8 @@ export default class DiscussionListItem<CustomAttrs extends IDiscussionListItemA
   /**
    * Determine whether or not the number of replies should be shown instead of
    * the number of unread posts.
-   *
-   * @return {boolean}
    */
-  showRepliesCount() {
+  showRepliesCount(): boolean {
     return this.attrs.params.sort === 'replies';
   }
 
@@ -210,7 +208,7 @@ export default class DiscussionListItem<CustomAttrs extends IDiscussionListItemA
     return items;
   }
 
-  replyCountItem() {
+  replyCountItem(): Mithril.Children {
     const discussion = this.attrs.discussion;
     const showUnread = !this.showRepliesCount() && discussion.isUnread();
 
diff --git a/framework/core/js/src/forum/components/DiscussionListPane.js b/framework/core/js/src/forum/components/DiscussionListPane.js
index 2c46f55c6..59ddef032 100644
--- a/framework/core/js/src/forum/components/DiscussionListPane.js
+++ b/framework/core/js/src/forum/components/DiscussionListPane.js
@@ -17,6 +17,9 @@ const hotEdge = (e) => {
  * - `state` A DiscussionListState object that represents the discussion lists's state.
  */
 export default class DiscussionListPane extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     if (!this.attrs.state.hasItems()) {
       return;
diff --git a/framework/core/js/src/forum/components/DiscussionPage.tsx b/framework/core/js/src/forum/components/DiscussionPage.tsx
index fd802ced9..506a5b27f 100644
--- a/framework/core/js/src/forum/components/DiscussionPage.tsx
+++ b/framework/core/js/src/forum/components/DiscussionPage.tsx
@@ -79,7 +79,7 @@ export default class DiscussionPage<CustomAttrs extends IDiscussionPageAttrs = I
     }
   }
 
-  view() {
+  view(): Mithril.Children {
     return (
       <div className="DiscussionPage">
         <DiscussionListPane state={app.discussions} />
diff --git a/framework/core/js/src/forum/components/DiscussionRenamedPost.js b/framework/core/js/src/forum/components/DiscussionRenamedPost.js
index 80aaa04f2..1514b114b 100644
--- a/framework/core/js/src/forum/components/DiscussionRenamedPost.js
+++ b/framework/core/js/src/forum/components/DiscussionRenamedPost.js
@@ -15,6 +15,9 @@ export default class DiscussionRenamedPost extends EventPost {
     return 'fas fa-pencil-alt';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   description(data) {
     const renamed = app.translator.trans('core.forum.post_stream.discussion_renamed_text', data);
     const oldName = app.translator.trans('core.forum.post_stream.discussion_renamed_old_tooltip', data);
@@ -22,6 +25,9 @@ export default class DiscussionRenamedPost extends EventPost {
     return <span title={extractText(oldName)}>{renamed}</span>;
   }
 
+  /**
+   * @return {Record<string, unknown>}
+   */
   descriptionData() {
     const post = this.attrs.post;
     const oldTitle = post.content()[0];
diff --git a/framework/core/js/src/forum/components/DiscussionsUserPage.js b/framework/core/js/src/forum/components/DiscussionsUserPage.js
index c4f4b056d..20bbe5b01 100644
--- a/framework/core/js/src/forum/components/DiscussionsUserPage.js
+++ b/framework/core/js/src/forum/components/DiscussionsUserPage.js
@@ -24,6 +24,9 @@ export default class DiscussionsUserPage extends UserPage {
     this.state.refresh();
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return <div className="DiscussionsUserPage">{DiscussionList.component({ state: this.state })}</div>;
   }
diff --git a/framework/core/js/src/forum/components/ForgotPasswordModal.tsx b/framework/core/js/src/forum/components/ForgotPasswordModal.tsx
index d3da52a9b..6fe920156 100644
--- a/framework/core/js/src/forum/components/ForgotPasswordModal.tsx
+++ b/framework/core/js/src/forum/components/ForgotPasswordModal.tsx
@@ -36,7 +36,7 @@ export default class ForgotPasswordModal<CustomAttrs extends IForgotPasswordModa
     return app.translator.trans('core.forum.forgot_password.title');
   }
 
-  content() {
+  content(): Mithril.Children {
     if (this.success) {
       return (
         <div className="Modal-body">
diff --git a/framework/core/js/src/forum/components/HeaderPrimary.js b/framework/core/js/src/forum/components/HeaderPrimary.js
index 55282fd22..cab4a4fb2 100644
--- a/framework/core/js/src/forum/components/HeaderPrimary.js
+++ b/framework/core/js/src/forum/components/HeaderPrimary.js
@@ -7,6 +7,9 @@ import listItems from '../../common/helpers/listItems';
  * default skin, these are shown just to the right of the forum title.
  */
 export default class HeaderPrimary extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return <ul className="Header-controls">{listItems(this.items().toArray())}</ul>;
   }
diff --git a/framework/core/js/src/forum/components/HeaderSecondary.js b/framework/core/js/src/forum/components/HeaderSecondary.js
index bc2d68a61..38f26255b 100644
--- a/framework/core/js/src/forum/components/HeaderSecondary.js
+++ b/framework/core/js/src/forum/components/HeaderSecondary.js
@@ -16,6 +16,9 @@ import Search from '../components/Search';
  * right side of the header.
  */
 export default class HeaderSecondary extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return <ul className="Header-controls">{listItems(this.items().toArray())}</ul>;
   }
diff --git a/framework/core/js/src/forum/components/IndexPage.js b/framework/core/js/src/forum/components/IndexPage.js
index a9bd9f345..2e3469566 100644
--- a/framework/core/js/src/forum/components/IndexPage.js
+++ b/framework/core/js/src/forum/components/IndexPage.js
@@ -45,6 +45,9 @@ export default class IndexPage extends Page {
     this.scrollTopOnCreate = false;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <div className="IndexPage">
diff --git a/framework/core/js/src/forum/components/LoadingPost.js b/framework/core/js/src/forum/components/LoadingPost.tsx
similarity index 91%
rename from framework/core/js/src/forum/components/LoadingPost.js
rename to framework/core/js/src/forum/components/LoadingPost.tsx
index c902ec883..1854134d5 100644
--- a/framework/core/js/src/forum/components/LoadingPost.js
+++ b/framework/core/js/src/forum/components/LoadingPost.tsx
@@ -1,3 +1,4 @@
+import type Mithril from 'mithril';
 import Component from '../../common/Component';
 import avatar from '../../common/helpers/avatar';
 
@@ -6,7 +7,7 @@ import avatar from '../../common/helpers/avatar';
  * indicating that the post is loading.
  */
 export default class LoadingPost extends Component {
-  view() {
+  view(): Mithril.Children {
     return (
       <div className="Post CommentPost LoadingPost">
         <header className="Post-header">
diff --git a/framework/core/js/src/forum/components/LogInButtons.js b/framework/core/js/src/forum/components/LogInButtons.tsx
similarity index 79%
rename from framework/core/js/src/forum/components/LogInButtons.js
rename to framework/core/js/src/forum/components/LogInButtons.tsx
index 692fd852c..0689c8209 100644
--- a/framework/core/js/src/forum/components/LogInButtons.js
+++ b/framework/core/js/src/forum/components/LogInButtons.tsx
@@ -1,3 +1,4 @@
+import Mithril from 'mithril';
 import Component from '../../common/Component';
 import ItemList from '../../common/utils/ItemList';
 
@@ -5,16 +6,14 @@ import ItemList from '../../common/utils/ItemList';
  * The `LogInButtons` component displays a collection of social login buttons.
  */
 export default class LogInButtons extends Component {
-  view() {
+  view(): Mithril.Children {
     return <div className="LogInButtons">{this.items().toArray()}</div>;
   }
 
   /**
    * Build a list of LogInButton components.
-   *
-   * @return {ItemList<import('mithril').Children>}
    */
   items() {
-    return new ItemList();
+    return new ItemList<Mithril.Children>();
   }
 }
diff --git a/framework/core/js/src/forum/components/LogInModal.tsx b/framework/core/js/src/forum/components/LogInModal.tsx
index 976cec7ad..6cd6d1f35 100644
--- a/framework/core/js/src/forum/components/LogInModal.tsx
+++ b/framework/core/js/src/forum/components/LogInModal.tsx
@@ -7,7 +7,7 @@ import LogInButtons from './LogInButtons';
 import extractText from '../../common/utils/extractText';
 import ItemList from '../../common/utils/ItemList';
 import Stream from '../../common/utils/Stream';
-import type Mithril from 'mithril';
+import Mithril from 'mithril';
 import RequestError from '../../common/utils/RequestError';
 
 export interface ILoginModalAttrs extends IInternalModalAttrs {
@@ -42,20 +42,20 @@ export default class LogInModal<CustomAttrs extends ILoginModalAttrs = ILoginMod
     return 'LogInModal Modal--small';
   }
 
-  title() {
+  title(): Mithril.Children {
     return app.translator.trans('core.forum.log_in.title');
   }
 
-  content() {
+  content(): Mithril.Children {
     return [<div className="Modal-body">{this.body()}</div>, <div className="Modal-footer">{this.footer()}</div>];
   }
 
-  body() {
+  body(): Mithril.Children {
     return [<LogInButtons />, <div className="Form Form--centered">{this.fields().toArray()}</div>];
   }
 
   fields() {
-    const items = new ItemList();
+    const items = new ItemList<Mithril.Children>();
 
     const identificationLabel = extractText(app.translator.trans('core.forum.log_in.username_or_email_placeholder'));
     const passwordLabel = extractText(app.translator.trans('core.forum.log_in.password_placeholder'));
@@ -124,7 +124,7 @@ export default class LogInModal<CustomAttrs extends ILoginModalAttrs = ILoginMod
     return items;
   }
 
-  footer() {
+  footer(): Mithril.Children {
     return [
       <p className="LogInModal-forgotPassword">
         <a onclick={this.forgotPassword.bind(this)}>{app.translator.trans('core.forum.log_in.forgot_password_link')}</a>
diff --git a/framework/core/js/src/forum/components/Notification.tsx b/framework/core/js/src/forum/components/Notification.tsx
index a0acdac33..e10a69687 100644
--- a/framework/core/js/src/forum/components/Notification.tsx
+++ b/framework/core/js/src/forum/components/Notification.tsx
@@ -18,7 +18,7 @@ export interface INotificationAttrs extends ComponentAttrs {
  * Subclasses should implement the `icon`, `href`, and `content` methods.
  */
 export default abstract class Notification<CustomAttrs extends INotificationAttrs = INotificationAttrs> extends Component<CustomAttrs> {
-  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>): Mithril.Children {
     const notification = this.attrs.notification;
     const href = this.href();
 
diff --git a/framework/core/js/src/forum/components/NotificationGrid.js b/framework/core/js/src/forum/components/NotificationGrid.js
index 368829873..216372a4d 100644
--- a/framework/core/js/src/forum/components/NotificationGrid.js
+++ b/framework/core/js/src/forum/components/NotificationGrid.js
@@ -38,6 +38,9 @@ export default class NotificationGrid extends Component {
     this.types = this.notificationTypes().toArray();
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const preferences = this.attrs.user.preferences();
 
diff --git a/framework/core/js/src/forum/components/NotificationList.js b/framework/core/js/src/forum/components/NotificationList.js
index 8c63fc328..572525484 100644
--- a/framework/core/js/src/forum/components/NotificationList.js
+++ b/framework/core/js/src/forum/components/NotificationList.js
@@ -12,6 +12,9 @@ import ItemList from '../../common/utils/ItemList';
  * notifications, grouped by discussion.
  */
 export default class NotificationList extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const state = this.attrs.state;
 
diff --git a/framework/core/js/src/forum/components/NotificationsDropdown.js b/framework/core/js/src/forum/components/NotificationsDropdown.js
index 6ec3bc3f0..43daa382b 100644
--- a/framework/core/js/src/forum/components/NotificationsDropdown.js
+++ b/framework/core/js/src/forum/components/NotificationsDropdown.js
@@ -18,6 +18,9 @@ export default class NotificationsDropdown extends Dropdown {
     super.initAttrs(attrs);
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getButton() {
     const newNotifications = this.getNewCount();
     const vdom = super.getButton();
@@ -30,6 +33,9 @@ export default class NotificationsDropdown extends Dropdown {
     return vdom;
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getButtonContent() {
     const unread = this.getUnreadCount();
 
@@ -40,6 +46,9 @@ export default class NotificationsDropdown extends Dropdown {
     ];
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getMenu() {
     return (
       <div className={classList('Dropdown-menu', this.attrs.menuClassName)} onclick={this.menuClick.bind(this)}>
diff --git a/framework/core/js/src/forum/components/NotificationsPage.js b/framework/core/js/src/forum/components/NotificationsPage.js
index b88da964a..f4e8cbbb5 100644
--- a/framework/core/js/src/forum/components/NotificationsPage.js
+++ b/framework/core/js/src/forum/components/NotificationsPage.js
@@ -17,6 +17,9 @@ export default class NotificationsPage extends Page {
     this.bodyClass = 'App--notifications';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     return (
       <div className="NotificationsPage">
diff --git a/framework/core/js/src/forum/components/Post.tsx b/framework/core/js/src/forum/components/Post.tsx
index a9683216a..d366ec9d0 100644
--- a/framework/core/js/src/forum/components/Post.tsx
+++ b/framework/core/js/src/forum/components/Post.tsx
@@ -45,7 +45,7 @@ export default abstract class Post<CustomAttrs extends IPostAttrs = IPostAttrs>
     );
   }
 
-  view(vnode: Mithril.Vnode<CustomAttrs, this>) {
+  view(vnode: Mithril.Vnode<CustomAttrs, this>): Mithril.Children {
     const attrs = this.elementAttrs();
 
     attrs.className = this.classes(attrs.className as string | undefined).join(' ');
diff --git a/framework/core/js/src/forum/components/PostEdited.js b/framework/core/js/src/forum/components/PostEdited.js
index 8d4db4cba..72eacb0a0 100644
--- a/framework/core/js/src/forum/components/PostEdited.js
+++ b/framework/core/js/src/forum/components/PostEdited.js
@@ -16,6 +16,9 @@ export default class PostEdited extends Component {
     super.oninit(vnode);
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const post = this.attrs.post;
     const editedUser = post.editedUser();
diff --git a/framework/core/js/src/forum/components/PostMeta.js b/framework/core/js/src/forum/components/PostMeta.js
index d85d84e33..118683bfa 100644
--- a/framework/core/js/src/forum/components/PostMeta.js
+++ b/framework/core/js/src/forum/components/PostMeta.js
@@ -13,6 +13,9 @@ import fullTime from '../../common/helpers/fullTime';
  * - `post`
  */
 export default class PostMeta extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const post = this.attrs.post;
     const time = post.createdAt();
diff --git a/framework/core/js/src/forum/components/PostPreview.js b/framework/core/js/src/forum/components/PostPreview.js
index 5293bd3c1..7cd4f1e24 100644
--- a/framework/core/js/src/forum/components/PostPreview.js
+++ b/framework/core/js/src/forum/components/PostPreview.js
@@ -14,6 +14,9 @@ import highlight from '../../common/helpers/highlight';
  * - `post`
  */
 export default class PostPreview extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const post = this.attrs.post;
     const user = post.user();
diff --git a/framework/core/js/src/forum/components/PostStream.js b/framework/core/js/src/forum/components/PostStream.js
index c3ff521ce..aa2f62f4b 100644
--- a/framework/core/js/src/forum/components/PostStream.js
+++ b/framework/core/js/src/forum/components/PostStream.js
@@ -26,6 +26,9 @@ export default class PostStream extends Component {
     this.scrollListener = new ScrollListener(this.onscroll.bind(this));
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     let lastTime;
 
diff --git a/framework/core/js/src/forum/components/PostStreamScrubber.js b/framework/core/js/src/forum/components/PostStreamScrubber.js
index cbdfe6060..7402506b1 100644
--- a/framework/core/js/src/forum/components/PostStreamScrubber.js
+++ b/framework/core/js/src/forum/components/PostStreamScrubber.js
@@ -23,6 +23,9 @@ export default class PostStreamScrubber extends Component {
     this.scrollListener = new ScrollListener(this.updateScrubberValues.bind(this, { fromScroll: true, forceHeightChange: true }));
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const count = this.stream.count();
 
diff --git a/framework/core/js/src/forum/components/PostUser.js b/framework/core/js/src/forum/components/PostUser.js
index d0b71c200..6b97d6c9b 100644
--- a/framework/core/js/src/forum/components/PostUser.js
+++ b/framework/core/js/src/forum/components/PostUser.js
@@ -15,6 +15,9 @@ import listItems from '../../common/helpers/listItems';
  * - `post`
  */
 export default class PostUser extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const post = this.attrs.post;
     const user = post.user();
diff --git a/framework/core/js/src/forum/components/PostsUserPage.js b/framework/core/js/src/forum/components/PostsUserPage.js
index 5c8f1901a..2163a2e8d 100644
--- a/framework/core/js/src/forum/components/PostsUserPage.js
+++ b/framework/core/js/src/forum/components/PostsUserPage.js
@@ -45,6 +45,9 @@ export default class PostsUserPage extends UserPage {
     this.loadUser(m.route.param('username'));
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     if (this.posts.length === 0 && !this.loading) {
       return (
diff --git a/framework/core/js/src/forum/components/RenameDiscussionModal.js b/framework/core/js/src/forum/components/RenameDiscussionModal.js
index 5b0c06669..cd1d332eb 100644
--- a/framework/core/js/src/forum/components/RenameDiscussionModal.js
+++ b/framework/core/js/src/forum/components/RenameDiscussionModal.js
@@ -19,10 +19,16 @@ export default class RenameDiscussionModal extends Modal {
     return 'RenameDiscussionModal Modal--small';
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   title() {
     return app.translator.trans('core.forum.rename_discussion.title');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return (
       <div className="Modal-body">
diff --git a/framework/core/js/src/forum/components/ReplyPlaceholder.js b/framework/core/js/src/forum/components/ReplyPlaceholder.js
index 2db3ca683..fcb9189a0 100644
--- a/framework/core/js/src/forum/components/ReplyPlaceholder.js
+++ b/framework/core/js/src/forum/components/ReplyPlaceholder.js
@@ -15,6 +15,9 @@ import listItems from '../../common/helpers/listItems';
  * - `discussion`
  */
 export default class ReplyPlaceholder extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     if (app.composer.composingReplyTo(this.attrs.discussion)) {
       return (
diff --git a/framework/core/js/src/forum/components/Search.tsx b/framework/core/js/src/forum/components/Search.tsx
index af15a207c..68e51702d 100644
--- a/framework/core/js/src/forum/components/Search.tsx
+++ b/framework/core/js/src/forum/components/Search.tsx
@@ -117,7 +117,7 @@ export default class Search<T extends SearchAttrs = SearchAttrs> extends Compone
     this.searchState = this.attrs.state;
   }
 
-  view() {
+  view(): Mithril.Children {
     const currentSearch = this.searchState.getInitialSearch();
 
     // Initialize search sources in the view rather than the constructor so
diff --git a/framework/core/js/src/forum/components/SessionDropdown.js b/framework/core/js/src/forum/components/SessionDropdown.js
index 456069cd2..5f607c631 100644
--- a/framework/core/js/src/forum/components/SessionDropdown.js
+++ b/framework/core/js/src/forum/components/SessionDropdown.js
@@ -22,10 +22,16 @@ export default class SessionDropdown extends Dropdown {
     attrs.accessibleToggleLabel = app.translator.trans('core.forum.header.session_dropdown_accessible_label');
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   view(vnode) {
     return super.view({ ...vnode, children: this.items().toArray() });
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   getButtonContent() {
     const user = app.session.user;
 
diff --git a/framework/core/js/src/forum/components/SettingsPage.js b/framework/core/js/src/forum/components/SettingsPage.js
index 40f82e20b..acb482805 100644
--- a/framework/core/js/src/forum/components/SettingsPage.js
+++ b/framework/core/js/src/forum/components/SettingsPage.js
@@ -22,6 +22,9 @@ export default class SettingsPage extends UserPage {
     app.setTitle(app.translator.trans('core.forum.settings.title'));
   }
 
+  /**
+   * @return {import('mithril').Children}
+   */
   content() {
     return (
       <div className="SettingsPage">
diff --git a/framework/core/js/src/forum/components/SignUpModal.tsx b/framework/core/js/src/forum/components/SignUpModal.tsx
index 779ac1bd6..c012495ae 100644
--- a/framework/core/js/src/forum/components/SignUpModal.tsx
+++ b/framework/core/js/src/forum/components/SignUpModal.tsx
@@ -6,7 +6,7 @@ import LogInButtons from './LogInButtons';
 import extractText from '../../common/utils/extractText';
 import ItemList from '../../common/utils/ItemList';
 import Stream from '../../common/utils/Stream';
-import type Mithril from 'mithril';
+import Mithril from 'mithril';
 
 export interface ISignupModalAttrs extends IInternalModalAttrs {
   username?: string;
@@ -49,11 +49,11 @@ export default class SignUpModal<CustomAttrs extends ISignupModalAttrs = ISignup
     return 'Modal--small SignUpModal';
   }
 
-  title() {
+  title(): Mithril.Children {
     return app.translator.trans('core.forum.sign_up.title');
   }
 
-  content() {
+  content(): Mithril.Children {
     return [<div className="Modal-body">{this.body()}</div>, <div className="Modal-footer">{this.footer()}</div>];
   }
 
@@ -61,12 +61,12 @@ export default class SignUpModal<CustomAttrs extends ISignupModalAttrs = ISignup
     return this.attrs.provided?.includes(field) ?? false;
   }
 
-  body() {
+  body(): Mithril.Children {
     return [!this.attrs.token && <LogInButtons />, <div className="Form Form--centered">{this.fields().toArray()}</div>];
   }
 
   fields() {
-    const items = new ItemList();
+    const items = new ItemList<Mithril.Children>();
 
     const usernameLabel = extractText(app.translator.trans('core.forum.sign_up.username_placeholder'));
     const emailLabel = extractText(app.translator.trans('core.forum.sign_up.email_placeholder'));
@@ -136,7 +136,7 @@ export default class SignUpModal<CustomAttrs extends ISignupModalAttrs = ISignup
     return items;
   }
 
-  footer() {
+  footer(): Mithril.Children {
     return [
       <p className="SignUpModal-logIn">{app.translator.trans('core.forum.sign_up.log_in_text', { a: <a onclick={this.logIn.bind(this)} /> })}</p>,
     ];
diff --git a/framework/core/js/src/forum/components/TerminalPost.js b/framework/core/js/src/forum/components/TerminalPost.js
index a3323e855..35a410270 100644
--- a/framework/core/js/src/forum/components/TerminalPost.js
+++ b/framework/core/js/src/forum/components/TerminalPost.js
@@ -12,6 +12,9 @@ import icon from '../../common/helpers/icon';
  * - `lastPost`
  */
 export default class TerminalPost extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const discussion = this.attrs.discussion;
     const lastPost = this.attrs.lastPost && discussion.replyCount();
diff --git a/framework/core/js/src/forum/components/UserCard.js b/framework/core/js/src/forum/components/UserCard.js
index 2236de191..2b2d56573 100644
--- a/framework/core/js/src/forum/components/UserCard.js
+++ b/framework/core/js/src/forum/components/UserCard.js
@@ -24,6 +24,9 @@ import listItems from '../../common/helpers/listItems';
  * - `controlsButtonClassName`
  */
 export default class UserCard extends Component {
+  /**
+   * @return {import('mithril').Children}
+   */
   view() {
     const user = this.attrs.user;
     const controls = UserControls.controls(user, this).toArray();
diff --git a/framework/core/js/src/forum/components/WelcomeHero.tsx b/framework/core/js/src/forum/components/WelcomeHero.tsx
index 55ec04682..034c7c466 100644
--- a/framework/core/js/src/forum/components/WelcomeHero.tsx
+++ b/framework/core/js/src/forum/components/WelcomeHero.tsx
@@ -21,7 +21,7 @@ export default class WelcomeHero extends Component<IWelcomeHeroAttrs> {
     super.oninit(vnode);
   }
 
-  view(vnode: Mithril.Vnode<IWelcomeHeroAttrs, this>) {
+  view(vnode: Mithril.Vnode<IWelcomeHeroAttrs, this>): Mithril.Children {
     if (this.isHidden()) return null;
 
     const slideUp = () => {