diff --git a/package-lock.json b/package-lock.json
index ccf0d03f6..ea569ced2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -39,6 +39,7 @@
         "@nextcloud/stylelint-config": "^3.2.1",
         "@nextcloud/vite-config": "^2.5.1",
         "@playwright/test": "^1.59.1",
+        "@types/node": "^25.6.1",
         "@vue/tsconfig": "^0.9.0",
         "eslint-config-prettier": "^10.1.8",
         "eslint-plugin-prettier": "^5.5.5",
@@ -3178,13 +3179,13 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "25.2.0",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-25.2.0.tgz",
-      "integrity": "sha512-DZ8VwRFUNzuqJ5khrvwMXHmvPe+zGayJhr2CDNiKB1WBE1ST8Djl00D0IC4vvNmHMdj6DlbYRIaFE7WHjlDl5w==",
+      "version": "25.6.1",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-25.6.1.tgz",
+      "integrity": "sha512-coJCN8O1q4AGyyqCAUSP06P+SrMTu18BkEj3NVAK07q6QUneD2wzj3CLv9+yP+BMeZQlMvneXqqvDe3w+xcq7g==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "undici-types": "~7.16.0"
+        "undici-types": "~7.19.0"
       }
     },
     "node_modules/@types/semver": {
@@ -11721,9 +11722,9 @@
       "license": "MIT"
     },
     "node_modules/undici-types": {
-      "version": "7.16.0",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",
-      "integrity": "sha512-Zz+aZWSj8LE6zoxD+xrjh4VfkIG8Ya6LvYkZqtUQGJPZjYl53ypCaUwWqo7eI0x66KBGeRo+mlBEkMSeSZ38Nw==",
+      "version": "7.19.2",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.19.2.tgz",
+      "integrity": "sha512-qYVnV5OEm2AW8cJMCpdV20CDyaN3g0AjDlOGf1OW4iaDEx8MwdtChUp4zu4H0VP3nDRF/8RKWH+IPp9uW0YGZg==",
       "dev": true,
       "license": "MIT"
     },
diff --git a/package.json b/package.json
index aa983a32b..dc0882c1b 100644
--- a/package.json
+++ b/package.json
@@ -59,6 +59,7 @@
     "@nextcloud/stylelint-config": "^3.2.1",
     "@nextcloud/vite-config": "^2.5.1",
     "@playwright/test": "^1.59.1",
+    "@types/node": "^25.6.1",
     "@vue/tsconfig": "^0.9.0",
     "eslint-config-prettier": "^10.1.8",
     "eslint-plugin-prettier": "^5.5.5",
diff --git a/src/Forms.vue b/src/Forms.vue
index af83b7e7e..9a096239a 100644
--- a/src/Forms.vue
+++ b/src/Forms.vue
@@ -168,8 +168,8 @@ import FormsIcon from './components/Icons/FormsIcon.vue'
 import Sidebar from './views/Sidebar.vue'
 import PermissionTypes from './mixins/PermissionTypes.js'
 import { FormState } from './models/Constants.ts'
-import logger from './utils/Logger.js'
-import OcsResponse2Data from './utils/OcsResponse2Data.js'
+import logger from './utils/Logger.ts'
+import OcsResponse2Data from './utils/OcsResponse2Data.ts'
 
 const appName = 'forms'
 
diff --git a/src/FormsSettings.vue b/src/FormsSettings.vue
index a25158ffb..e9da16bf0 100644
--- a/src/FormsSettings.vue
+++ b/src/FormsSettings.vue
@@ -105,7 +105,7 @@ import NcInputField from '@nextcloud/vue/components/NcInputField'
 import NcNoteCard from '@nextcloud/vue/components/NcNoteCard'
 import NcSelect from '@nextcloud/vue/components/NcSelect'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
-import logger from './utils/Logger.js'
+import logger from './utils/Logger.ts'
 
 export default {
 	name: 'FormsSettings',
diff --git a/src/components/AppNavigationForm.vue b/src/components/AppNavigationForm.vue
index 31c52352f..35ec1ceaf 100644
--- a/src/components/AppNavigationForm.vue
+++ b/src/components/AppNavigationForm.vue
@@ -115,7 +115,7 @@ import IconDelete from 'vue-material-design-icons/TrashCanOutline.vue'
 import FormsIcon from './Icons/FormsIcon.vue'
 import PermissionTypes from '../mixins/PermissionTypes.js'
 import { FormState } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
+import logger from '../utils/Logger.ts'
 
 export default {
 	name: 'AppNavigationForm',
diff --git a/src/components/QRDialog.vue b/src/components/QRDialog.vue
index a5325f899..66e691d92 100644
--- a/src/components/QRDialog.vue
+++ b/src/components/QRDialog.vue
@@ -26,7 +26,7 @@
 <script>
 import QRCode from 'qrcode'
 import NcDialog from '@nextcloud/vue/components/NcDialog'
-import logger from '../utils/Logger.js'
+import logger from '../utils/Logger.ts'
 
 export default {
 	name: 'QRDialog',
diff --git a/src/components/Questions/AnswerInput.vue b/src/components/Questions/AnswerInput.vue
index a40b36dea..895c7db72 100644
--- a/src/components/Questions/AnswerInput.vue
+++ b/src/components/Questions/AnswerInput.vue
@@ -98,8 +98,8 @@ import IconTableRow from 'vue-material-design-icons/TableRow.vue'
 import IconDelete from 'vue-material-design-icons/TrashCanOutline.vue'
 import IconDragIndicator from '../Icons/IconDragIndicator.vue'
 import { INPUT_DEBOUNCE_MS, OptionType } from '../../models/Constants.ts'
-import logger from '../../utils/Logger.js'
-import OcsResponse2Data from '../../utils/OcsResponse2Data.js'
+import logger from '../../utils/Logger.ts'
+import OcsResponse2Data from '../../utils/OcsResponse2Data.ts'
 
 export default {
 	name: 'AnswerInput',
diff --git a/src/components/Questions/QuestionFile.vue b/src/components/Questions/QuestionFile.vue
index a4e85bea3..679515ab8 100644
--- a/src/components/Questions/QuestionFile.vue
+++ b/src/components/Questions/QuestionFile.vue
@@ -166,8 +166,8 @@ import IconUploadMultiple from 'vue-material-design-icons/UploadMultipleOutline.
 import Question from './Question.vue'
 import QuestionMixin from '../../mixins/QuestionMixin.js'
 import fileTypes from '../../models/FileTypes.js'
-import logger from '../../utils/Logger.js'
-import OcsResponse2Data from '../../utils/OcsResponse2Data.js'
+import logger from '../../utils/Logger.ts'
+import OcsResponse2Data from '../../utils/OcsResponse2Data.ts'
 
 /**
  * A constant object representing file size units in bytes.
diff --git a/src/components/Questions/QuestionShort.vue b/src/components/Questions/QuestionShort.vue
index b14514440..458b1857b 100644
--- a/src/components/Questions/QuestionShort.vue
+++ b/src/components/Questions/QuestionShort.vue
@@ -79,7 +79,7 @@ import IconRegex from 'vue-material-design-icons/Regex.vue'
 import Question from './Question.vue'
 import QuestionMixin from '../../mixins/QuestionMixin.js'
 import validationTypes from '../../models/ValidationTypes.js'
-import { splitRegex, validateExpression } from '../../utils/RegularExpression.js'
+import { splitRegex, validateExpression } from '../../utils/RegularExpression.ts'
 
 export default {
 	name: 'QuestionShort',
diff --git a/src/components/SidebarTabs/SharingSidebarTab.vue b/src/components/SidebarTabs/SharingSidebarTab.vue
index 07fdd32fc..8457172a4 100644
--- a/src/components/SidebarTabs/SharingSidebarTab.vue
+++ b/src/components/SidebarTabs/SharingSidebarTab.vue
@@ -227,8 +227,8 @@ import SharingShareDiv from './SharingShareDiv.vue'
 import PermissionTypes from '../../mixins/PermissionTypes.js'
 import ShareLinkMixin from '../../mixins/ShareLinkMixin.js'
 import ShareTypes from '../../mixins/ShareTypes.js'
-import logger from '../../utils/Logger.js'
-import OcsResponse2Data from '../../utils/OcsResponse2Data.js'
+import logger from '../../utils/Logger.ts'
+import OcsResponse2Data from '../../utils/OcsResponse2Data.ts'
 
 export default {
 	components: {
diff --git a/src/components/SidebarTabs/TransferOwnership.vue b/src/components/SidebarTabs/TransferOwnership.vue
index 8a6340eae..44e3491f7 100644
--- a/src/components/SidebarTabs/TransferOwnership.vue
+++ b/src/components/SidebarTabs/TransferOwnership.vue
@@ -101,7 +101,7 @@ import NcDialog from '@nextcloud/vue/components/NcDialog'
 import NcSelectUsers from '@nextcloud/vue/components/NcSelectUsers'
 import NcTextField from '@nextcloud/vue/components/NcTextField'
 import UserSearchMixin from '../../mixins/UserSearchMixin.js'
-import logger from '../../utils/Logger.js'
+import logger from '../../utils/Logger.ts'
 
 export default {
 	components: {
diff --git a/src/components/TopBar.vue b/src/components/TopBar.vue
index f49559031..326a78b61 100644
--- a/src/components/TopBar.vue
+++ b/src/components/TopBar.vue
@@ -38,7 +38,7 @@ import NcButton from '@nextcloud/vue/components/NcButton'
 import IconShareVariant from 'vue-material-design-icons/ShareVariantOutline.vue'
 import PillMenu from './PillMenu.vue'
 import PermissionTypes from '../mixins/PermissionTypes.js'
-import logger from '../utils/Logger.js'
+import logger from '../utils/Logger.ts'
 
 const submitView = {
 	ariaLabel: t('forms', 'View form'),
diff --git a/src/emptyContent.js b/src/emptyContent.ts
similarity index 95%
rename from src/emptyContent.js
rename to src/emptyContent.ts
index 73558934b..b6a7763cb 100644
--- a/src/emptyContent.js
+++ b/src/emptyContent.ts
@@ -12,3 +12,5 @@ const app = createApp(FormsEmptyContent)
 app.config.globalProperties.t = translate
 app.config.globalProperties.n = translatePlural
 app.mount('#content')
+
+export default app
diff --git a/src/main.js b/src/main.ts
similarity index 93%
rename from src/main.js
rename to src/main.ts
index a01a680d9..0da0e0705 100644
--- a/src/main.js
+++ b/src/main.ts
@@ -6,7 +6,7 @@
 import { translate, translatePlural } from '@nextcloud/l10n'
 import { createApp } from 'vue'
 import Forms from './Forms.vue'
-import router from './router.js'
+import router from './router.ts'
 
 import 'vite/modulepreload-polyfill'
 import '@nextcloud/dialogs/style.css'
diff --git a/src/mixins/QuestionMixin.js b/src/mixins/QuestionMixin.js
index fa214f2a9..6741fc257 100644
--- a/src/mixins/QuestionMixin.js
+++ b/src/mixins/QuestionMixin.js
@@ -9,8 +9,8 @@ import { generateOcsUrl } from '@nextcloud/router'
 import debounce from 'debounce'
 import Question from '../components/Questions/Question.vue'
 import { INPUT_DEBOUNCE_MS, OptionType } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
 
 export default {
 	inheritAttrs: false,
diff --git a/src/mixins/QuestionMultipleMixin.ts b/src/mixins/QuestionMultipleMixin.ts
index ae1472497..5bafa8e4e 100644
--- a/src/mixins/QuestionMultipleMixin.ts
+++ b/src/mixins/QuestionMultipleMixin.ts
@@ -13,41 +13,62 @@ import { generateOcsUrl } from '@nextcloud/router'
 import debounce from 'debounce'
 import { defineComponent } from 'vue'
 import { INPUT_DEBOUNCE_MS, OptionType } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
+import logger from '../utils/Logger.ts'
+
+// Temporary augmentation to allow using `this.<prop>` in mixin methods
+declare module '@vue/runtime-core' {
+	interface ComponentCustomProperties {
+		options: FormsOption[]
+		values: unknown[]
+		answerType: { validate: (ctx: unknown) => boolean }
+		readOnly: boolean
+		extraSettings?: unknown
+		formId: number
+		id: number
+		shuffleArray: <T>(arr: T[]) => T[]
+		$refs: Record<string, unknown>
+	}
+}
 
 export default defineComponent({
 	emits: ['update:options'],
 
 	data() {
 		return {
-			dirtyOptionsType: null,
+			dirtyOptionsType: null as string | null,
 		}
 	},
 
 	computed: {
-		areNoneChecked() {
+		areNoneChecked(): boolean {
 			return this.values.length === 0
 		},
 
-		contentValid() {
+		contentValid(): boolean {
 			return this.answerType.validate(this)
 		},
 
-		isLastEmpty() {
-			const value = this.options[this.options.length - 1]
+		isLastEmpty(): boolean {
+			const value = this.options[this.options.length - 1] as
+				| FormsOption
+				| undefined
 			return value?.text?.trim?.().length === 0
 		},
 
-		expectedOptionTypes() {
+		expectedOptionTypes(): OptionType[] {
 			return [OptionType.Choice, OptionType.Row, OptionType.Column]
 		},
 
 		sortedOptionsPerType(): { [key: string]: FormsOption[] } {
-			const optionsPerType = Object.fromEntries(
-				this.expectedOptionTypes.map((optionType) => [optionType, []]),
-			)
+			const optionsPerType: { [key: string]: FormsOption[] } =
+				Object.fromEntries(
+					this.expectedOptionTypes.map((optionType) => [
+						optionType,
+						[] as FormsOption[],
+					]),
+				)
 
-			this.options.forEach((option) => {
+			this.options.forEach((option: FormsOption) => {
 				optionsPerType[option.optionType].push(option)
 			})
 
@@ -69,14 +90,15 @@ export default defineComponent({
 					})
 
 					if (!this.readOnly) {
-						// In edit mode append an empty option
+						// In edit mode append an empty option (cast as FormsOption temporarily)
 						optionsPerType[optionType].push({
+							id: 0,
 							local: true,
 							questionId: this.id,
 							text: '',
 							optionType,
 							order: optionsPerType[optionType].length,
-						})
+						} as FormsOption)
 					}
 				}
 			}
@@ -104,7 +126,7 @@ export default defineComponent({
 		 */
 		focusIndex(index: number, optionType: string) {
 			// refs are not guaranteed to be in correct order - we need to find the correct item
-			const item = this.$refs.input.find((instance) => {
+			const item = this.$refs.input.find((instance: unknown) => {
 				return (
 					instance.$props.optionType === optionType
 					&& instance.$props.index === index
@@ -143,12 +165,13 @@ export default defineComponent({
 				return [
 					...options,
 					{
+						id: 0,
 						local: true,
 						questionId: this.id,
 						text: '',
 						optionType,
 						order: options.length,
-					},
+					} as FormsOption,
 				]
 			}
 			return options
@@ -386,7 +409,7 @@ export default defineComponent({
 	},
 
 	watch: {
-		dirtyOptionsType: debounce(function () {
+		dirtyOptionsType: debounce(function (this: unknown) {
 			if (!this.dirtyOptionsType) {
 				return
 			}
diff --git a/src/mixins/ShareLinkMixin.js b/src/mixins/ShareLinkMixin.js
index 267820b70..5a64fd503 100644
--- a/src/mixins/ShareLinkMixin.js
+++ b/src/mixins/ShareLinkMixin.js
@@ -4,7 +4,7 @@ import { showError, showSuccess } from '@nextcloud/dialogs'
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
 import { generateUrl } from '@nextcloud/router'
-import logger from '../utils/Logger.js'
+import logger from '../utils/Logger.ts'
 
 export default {
 	methods: {
diff --git a/src/mixins/UserSearchMixin.js b/src/mixins/UserSearchMixin.js
index ffc50e8c8..4eded6b06 100644
--- a/src/mixins/UserSearchMixin.js
+++ b/src/mixins/UserSearchMixin.js
@@ -7,8 +7,8 @@ import axios from '@nextcloud/axios'
 import { generateOcsUrl } from '@nextcloud/router'
 import debounce from 'debounce'
 import { INPUT_DEBOUNCE_MS } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
 import ShareTypes from './ShareTypes.js'
 
 export default {
diff --git a/src/mixins/ViewsMixin.js b/src/mixins/ViewsMixin.js
index 87e78e020..e1b8e3446 100644
--- a/src/mixins/ViewsMixin.js
+++ b/src/mixins/ViewsMixin.js
@@ -10,9 +10,9 @@ import { emit } from '@nextcloud/event-bus'
 import moment from '@nextcloud/moment'
 import { generateOcsUrl } from '@nextcloud/router'
 import MarkdownIt from 'markdown-it'
-import CancelableRequest from '../utils/CancelableRequest.js'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
+import CancelableRequest from '../utils/CancelableRequest.ts'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
 
 export default {
 	provide() {
diff --git a/src/router.js b/src/router.js
deleted file mode 100644
index ec1f04acf..000000000
--- a/src/router.js
+++ /dev/null
@@ -1,48 +0,0 @@
-/**
- * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
- * SPDX-License-Identifier: AGPL-3.0-or-later
- */
-
-import { generateUrl } from '@nextcloud/router'
-import { createRouter, createWebHistory } from 'vue-router'
-
-const Create = () => import('./views/Create.vue')
-const Results = () => import('./views/Results.vue')
-const Submit = () => import('./views/Submit.vue')
-
-const router = createRouter({
-	history: createWebHistory(generateUrl('/apps/forms', '')),
-	linkActiveClass: 'active',
-	routes: [
-		{
-			path: '/',
-			name: 'root',
-		},
-		{
-			path: '/:hash',
-			redirect: { name: 'submit' },
-			name: 'formRoot',
-			props: true,
-		},
-		{
-			path: '/:hash/edit',
-			components: { default: Create },
-			name: 'edit',
-			props: { default: true },
-		},
-		{
-			path: '/:hash/results',
-			components: { default: Results },
-			name: 'results',
-			props: { default: true },
-		},
-		{
-			path: '/:hash/submit/:submissionId?',
-			components: { default: Submit },
-			name: 'submit',
-			props: { default: true },
-		},
-	],
-})
-
-export default router
diff --git a/src/router.ts b/src/router.ts
new file mode 100644
index 000000000..6d37b34f8
--- /dev/null
+++ b/src/router.ts
@@ -0,0 +1,54 @@
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import type { RouteRecordRaw } from 'vue-router'
+
+import { generateUrl } from '@nextcloud/router'
+import { createRouter, createWebHistory } from 'vue-router'
+
+const Create = () => import('./views/Create.vue')
+const Results = () => import('./views/Results.vue')
+const Submit = () => import('./views/Submit.vue')
+const EmptyContent = () => import('./FormsEmptyContent.vue')
+
+const routes = [
+	{
+		path: '/',
+		name: 'root',
+		components: { default: EmptyContent },
+	},
+	{
+		path: '/:hash',
+		redirect: { name: 'submit' },
+		name: 'formRoot',
+		props: true,
+	},
+	{
+		path: '/:hash/edit',
+		components: { default: Create },
+		name: 'edit',
+		props: { default: true },
+	},
+	{
+		path: '/:hash/results',
+		components: { default: Results },
+		name: 'results',
+		props: { default: true },
+	},
+	{
+		path: '/:hash/submit/:submissionId?',
+		components: { default: Submit },
+		name: 'submit',
+		props: { default: true },
+	},
+]
+
+const router = createRouter({
+	history: createWebHistory(generateUrl('/apps/forms')),
+	linkActiveClass: 'active',
+	routes: routes as unknown as RouteRecordRaw[],
+})
+
+export default router
diff --git a/src/settings.js b/src/settings.ts
similarity index 100%
rename from src/settings.js
rename to src/settings.ts
diff --git a/src/submit.js b/src/submit.ts
similarity index 100%
rename from src/submit.js
rename to src/submit.ts
diff --git a/src/types/vite-modulepreload.d.ts b/src/types/vite-modulepreload.d.ts
new file mode 100644
index 000000000..a9f0f88af
--- /dev/null
+++ b/src/types/vite-modulepreload.d.ts
@@ -0,0 +1,6 @@
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+declare module 'vite/modulepreload-polyfill'
diff --git a/src/utils/CancelableRequest.js b/src/utils/CancelableRequest.ts
similarity index 58%
rename from src/utils/CancelableRequest.js
rename to src/utils/CancelableRequest.ts
index 94feb65c9..01bbdd328 100644
--- a/src/utils/CancelableRequest.js
+++ b/src/utils/CancelableRequest.ts
@@ -5,13 +5,15 @@
 
 import axios from '@nextcloud/axios'
 
+type RequestFn = (url: string, options?: unknown) => Promise<unknown>
+
 /**
  * Creates a cancelable axios 'request object'.
  *
- * @param {Function} request the axios promise request
- * @return {object}
+ * @param request the axios promise request
+ * @return
  */
-function CancelableRequest(request) {
+export default function CancelableRequest(request: RequestFn) {
 	/**
 	 * Generate an axios cancel token
 	 */
@@ -21,10 +23,10 @@ function CancelableRequest(request) {
 	/**
 	 * Execute the request
 	 *
-	 * @param {string} url the url to send the request to
-	 * @param {object} [options] optional config for the request
+	 * @param url the url to send the request to
+	 * @param [options] optional config for the request
 	 */
-	const fetch = async function (url, options) {
+	const fetch = async function (url: string, options?: Array<unknown>) {
 		return request(url, { cancelToken: source.token, ...options })
 	}
 	return {
@@ -32,5 +34,3 @@ function CancelableRequest(request) {
 		cancel: source.cancel,
 	}
 }
-
-export default CancelableRequest
diff --git a/src/utils/Logger.js b/src/utils/Logger.ts
similarity index 100%
rename from src/utils/Logger.js
rename to src/utils/Logger.ts
diff --git a/src/utils/OcsResponse2Data.js b/src/utils/OcsResponse2Data.ts
similarity index 58%
rename from src/utils/OcsResponse2Data.js
rename to src/utils/OcsResponse2Data.ts
index 346f3fdf5..344dd50f0 100644
--- a/src/utils/OcsResponse2Data.js
+++ b/src/utils/OcsResponse2Data.ts
@@ -7,11 +7,9 @@
  * Extract actual data from Axios OCS response
  * Just a small wrapper for nice code.
  *
- * @param {object} response response returned by axios
- * @return {object} The actual data out of the ocs response
+ * @param response response returned by axios
+ * @return The actual data out of the ocs response
  */
-function OcsResponse2Data(response) {
+export default function OcsResponse2Data(response: unknown): unknown {
 	return response.data.ocs.data
 }
-
-export default OcsResponse2Data
diff --git a/src/utils/RegularExpression.js b/src/utils/RegularExpression.ts
similarity index 70%
rename from src/utils/RegularExpression.js
rename to src/utils/RegularExpression.ts
index 1971c89e7..38cdb5347 100644
--- a/src/utils/RegularExpression.js
+++ b/src/utils/RegularExpression.ts
@@ -15,27 +15,23 @@ const REGEX_UNESCAPED_SLASH = /(?:^|[^\\])(?:\\\\)*\//
 /**
  * Check if a regex is valid and enclosed with delimiters
  *
- * @param {string} input regular expression
- * @return {boolean}
+ * @param input regular expression
+ * @return is expression valid
  */
-export function validateExpression(input) {
-	// empty regex passes
+export function validateExpression(input: string): boolean {
 	if (input.length === 0) {
 		return true
 	}
 
-	// Validate regex has delimters
 	if (!REGEX_WITH_DELIMITERS.test(input)) {
 		return false
 	}
 
-	// Check pattern is escaped
 	const { pattern, modifiers } = splitRegex(input)
 	if (REGEX_UNESCAPED_SLASH.test(pattern)) {
 		return false
 	}
 
-	// Check if regular expression can be compiled
 	try {
 		;(() => new RegExp(pattern, modifiers))()
 		return true
@@ -47,10 +43,10 @@ export function validateExpression(input) {
 /**
  * Split an enclosed regular expression into pattern and modifiers
  *
- * @param {string} regex regular expression with delimiters
- * @return {{pattern: string, modifiers: string}} pattern and modifiers
+ * @param regex regular expression with delimiters
+ * @return pattern and modifiers
  */
-export function splitRegex(regex) {
+export function splitRegex(regex: string): { pattern: string; modifiers: string } {
 	const [, pattern, modifiers] = regex.match(REGEX_WITH_DELIMITERS) || ['', '', '']
 	return { pattern, modifiers }
 }
diff --git a/src/utils/SetWindowTitle.js b/src/utils/SetWindowTitle.js
deleted file mode 100644
index 28e57832c..000000000
--- a/src/utils/SetWindowTitle.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/**
- * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
- * SPDX-License-Identifier: AGPL-3.0-or-later
- */
-
-/**
- * Set the Window-Title to current FormTitle including suffix.
- *
- * @param {string} formTitle Title of current form to set on window.
- */
-function SetWindowTitle(formTitle) {
-	if (formTitle === '') {
-		window.document.title = t('forms', 'Forms') + ' - ' + OC.theme.title
-	} else {
-		window.document.title =
-			formTitle + ' - ' + t('forms', 'Forms') + ' - ' + OC.theme.title
-	}
-}
-
-export default SetWindowTitle
diff --git a/src/utils/SetWindowTitle.ts b/src/utils/SetWindowTitle.ts
new file mode 100644
index 000000000..dd9bcd541
--- /dev/null
+++ b/src/utils/SetWindowTitle.ts
@@ -0,0 +1,20 @@
+/**
+ * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { t } from '@nextcloud/l10n'
+
+/**
+ * Set the Window-Title to current FormTitle including suffix.
+ *
+ * @param formTitle Title of current form to set on window.
+ */
+export default function SetWindowTitle(formTitle: string): void {
+	if (formTitle === '') {
+		window.document.title = t('forms', 'Forms') + ' - ' + window.OC.theme.title
+	} else {
+		window.document.title =
+			formTitle + ' - ' + t('forms', 'Forms') + ' - ' + window.OC.theme.title
+	}
+}
diff --git a/src/views/Create.vue b/src/views/Create.vue
index c2abebcf9..ddfbec781 100644
--- a/src/views/Create.vue
+++ b/src/views/Create.vue
@@ -251,9 +251,9 @@ import TopBar from '../components/TopBar.vue'
 import ViewsMixin from '../mixins/ViewsMixin.js'
 import answerTypes from '../models/AnswerTypes.js'
 import { FormState, INPUT_DEBOUNCE_MS } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
-import SetWindowTitle from '../utils/SetWindowTitle.js'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
+import SetWindowTitle from '../utils/SetWindowTitle.ts'
 
 window.axios = axios
 
diff --git a/src/views/Results.vue b/src/views/Results.vue
index b9258ae66..aff85912f 100644
--- a/src/views/Results.vue
+++ b/src/views/Results.vue
@@ -311,9 +311,9 @@ import PermissionTypes from '../mixins/PermissionTypes.js'
 import ViewsMixin from '../mixins/ViewsMixin.js'
 import answerTypes from '../models/AnswerTypes.js'
 import { FormState, INPUT_DEBOUNCE_MS } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
-import SetWindowTitle from '../utils/SetWindowTitle.js'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
+import SetWindowTitle from '../utils/SetWindowTitle.ts'
 
 const SUPPORTED_FILE_FORMATS = {
 	ods: IconTableSvg,
diff --git a/src/views/Submit.vue b/src/views/Submit.vue
index ffcd9b3a4..1ac3ffbb3 100644
--- a/src/views/Submit.vue
+++ b/src/views/Submit.vue
@@ -240,9 +240,9 @@ import {
 	FormState,
 	QUESTION_EXTRASETTINGS_OTHER_PREFIX,
 } from '../models/Constants.ts'
-import logger from '../utils/Logger.js'
-import OcsResponse2Data from '../utils/OcsResponse2Data.js'
-import SetWindowTitle from '../utils/SetWindowTitle.js'
+import logger from '../utils/Logger.ts'
+import OcsResponse2Data from '../utils/OcsResponse2Data.ts'
+import SetWindowTitle from '../utils/SetWindowTitle.ts'
 
 export default {
 	// eslint-disable-next-line vue/multi-word-component-names
diff --git a/tsconfig.json b/tsconfig.json
index a2f6f9707..6794d7586 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,11 +5,12 @@
 
 {
 	"extends": "@vue/tsconfig",
-	"include": ["src/**.ts", "*.ts"],
+	"include": ["src/**/*", "*.ts"],
 	"compilerOptions": {
 		"allowJs": true,
 		"target": "ESNext",
 		"module": "ESNext",
-		"moduleResolution": "Bundler"
+		"moduleResolution": "Bundler",
+		"types": ["vite/client", "node"]
 	}
 }
diff --git a/vite.config.js b/vite.config.js
index f454bf373..7b7c0f07f 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -8,10 +8,10 @@ import { join, resolve } from 'path'
 
 export default createAppConfig(
 	{
-		emptyContent: resolve(join('src', 'emptyContent.js')),
-		main: resolve(join('src', 'main.js')),
-		submit: resolve(join('src', 'submit.js')),
-		settings: resolve(join('src', 'settings.js')),
+		emptyContent: resolve(join('src', 'emptyContent.ts')),
+		main: resolve(join('src', 'main.ts')),
+		submit: resolve(join('src', 'submit.ts')),
+		settings: resolve(join('src', 'settings.ts')),
 	},
 	{
 		config: {