diff --git a/docs/contributing/coding-standards/js.md b/docs/contributing/coding-standards/js.md
index de29e1aef2..1e413d5bb6 100644
--- a/docs/contributing/coding-standards/js.md
+++ b/docs/contributing/coding-standards/js.md
@@ -15,9 +15,12 @@ component
 ```mjs
 /**
  * Component name
+ *
+ * @preserve
  */
 export class Example {
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for component
    */
   constructor ($module) {
@@ -32,6 +35,8 @@ export class Example {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/accordion/accordion.mjs b/packages/govuk-frontend/src/govuk/components/accordion/accordion.mjs
index 49b52be968..50d1932680 100644
--- a/packages/govuk-frontend/src/govuk/components/accordion/accordion.mjs
+++ b/packages/govuk-frontend/src/govuk/components/accordion/accordion.mjs
@@ -13,6 +13,8 @@ import { I18n } from '../../i18n.mjs'
  *
  * The state of each section is saved to the DOM via the `aria-expanded`
  * attribute, which also provides accessibility.
+ *
+ * @preserve
  */
 export class Accordion {
   /** @private */
@@ -109,6 +111,7 @@ export class Accordion {
   $showAllText = null
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for accordion
    * @param {AccordionConfig} [config] - Accordion config
    */
@@ -138,6 +141,8 @@ export class Accordion {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/button/button.mjs b/packages/govuk-frontend/src/govuk/components/button/button.mjs
index 99af1fbef9..dbee7e816a 100644
--- a/packages/govuk-frontend/src/govuk/components/button/button.mjs
+++ b/packages/govuk-frontend/src/govuk/components/button/button.mjs
@@ -6,6 +6,8 @@ const DEBOUNCE_TIMEOUT_IN_SECONDS = 1
 
 /**
  * JavaScript enhancements for the Button component
+ *
+ * @preserve
  */
 export class Button {
   /** @private */
@@ -24,7 +26,7 @@ export class Button {
   debounceFormSubmitTimer = null
 
   /**
-   *
+   * @preserve
    * @param {Element} $module - HTML element to use for button
    * @param {ButtonConfig} [config] - Button config
    */
@@ -44,6 +46,8 @@ export class Button {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs b/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
index 5df1f0d195..e6dbf2f542 100644
--- a/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
+++ b/packages/govuk-frontend/src/govuk/components/character-count/character-count.mjs
@@ -12,6 +12,8 @@ import { I18n } from '../../i18n.mjs'
  *
  * You can configure the message to only appear after a certain percentage
  * of the available characters/words has been entered.
+ *
+ * @preserve
  */
 export class CharacterCount {
   /** @private */
@@ -60,6 +62,7 @@ export class CharacterCount {
   maxLength = Infinity
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for character count
    * @param {CharacterCountConfig} [config] - Character count config
    */
@@ -123,6 +126,8 @@ export class CharacterCount {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.mjs b/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.mjs
index f49cfb671c..36486d7de5 100644
--- a/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.mjs
+++ b/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.mjs
@@ -1,5 +1,7 @@
 /**
  * Checkboxes component
+ *
+ * @preserve
  */
 export class Checkboxes {
   /** @private */
@@ -9,6 +11,7 @@ export class Checkboxes {
   $inputs
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for checkboxes
    */
   constructor ($module) {
@@ -39,6 +42,8 @@ export class Checkboxes {
    * We also need to restore the state of any conditional reveals on the page (for
    * example if the user has navigated back), and set up event handlers to keep
    * the reveal in sync with the checkbox state.
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
index 56459579d3..d36155eeb5 100644
--- a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
+++ b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.mjs
@@ -5,6 +5,8 @@ import { normaliseDataset } from '../../common/normalise-dataset.mjs'
  * Error summary component
  *
  * Takes focus on initialisation for accessible announcement, unless disabled in configuration.
+ *
+ * @preserve
  */
 export class ErrorSummary {
   /** @private */
@@ -17,7 +19,7 @@ export class ErrorSummary {
   config
 
   /**
-   *
+   * @preserve
    * @param {Element} $module - HTML element to use for error summary
    * @param {ErrorSummaryConfig} [config] - Error summary config
    */
@@ -44,6 +46,8 @@ export class ErrorSummary {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.mjs b/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.mjs
index c53f6f1edc..d9a25dd0bc 100644
--- a/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.mjs
+++ b/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.mjs
@@ -4,6 +4,8 @@ import { I18n } from '../../i18n.mjs'
 
 /**
  * Exit This Page component
+ *
+ * @preserve
  */
 export class ExitThisPage {
   /** @private */
@@ -71,6 +73,7 @@ export class ExitThisPage {
   timeoutMessageId = null
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element that wraps the Exit This Page button
    * @param {ExitThisPageConfig} [config] - Exit This Page config
    */
@@ -102,6 +105,8 @@ export class ExitThisPage {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     this.buildIndicator()
diff --git a/packages/govuk-frontend/src/govuk/components/header/header.mjs b/packages/govuk-frontend/src/govuk/components/header/header.mjs
index 803b028c74..caf68a3e88 100644
--- a/packages/govuk-frontend/src/govuk/components/header/header.mjs
+++ b/packages/govuk-frontend/src/govuk/components/header/header.mjs
@@ -1,5 +1,7 @@
 /**
  * Header component
+ *
+ * @preserve
  */
 export class Header {
   /** @private */
@@ -32,6 +34,7 @@ export class Header {
   mql = null
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for header
    */
   constructor ($module) {
@@ -53,6 +56,8 @@ export class Header {
    * missing then there's nothing to do so return early.
    * Apply a matchMedia for desktop which will trigger a state sync if the browser
    * viewport moves between states.
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.mjs b/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.mjs
index 7fdee3ac74..5925212604 100644
--- a/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.mjs
+++ b/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.mjs
@@ -3,6 +3,8 @@ import { normaliseDataset } from '../../common/normalise-dataset.mjs'
 
 /**
  * Notification Banner component
+ *
+ * @preserve
  */
 export class NotificationBanner {
   /** @private */
@@ -15,6 +17,7 @@ export class NotificationBanner {
   config
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for notification banner
    * @param {NotificationBannerConfig} [config] - Notification banner config
    */
@@ -34,6 +37,8 @@ export class NotificationBanner {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/radios/radios.mjs b/packages/govuk-frontend/src/govuk/components/radios/radios.mjs
index 52576d0364..931e3603a4 100644
--- a/packages/govuk-frontend/src/govuk/components/radios/radios.mjs
+++ b/packages/govuk-frontend/src/govuk/components/radios/radios.mjs
@@ -1,5 +1,7 @@
 /**
  * Radios component
+ *
+ * @preserve
  */
 export class Radios {
   /** @private */
@@ -9,6 +11,7 @@ export class Radios {
   $inputs
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for radios
    */
   constructor ($module) {
@@ -39,6 +42,8 @@ export class Radios {
    * We also need to restore the state of any conditional reveals on the page (for
    * example if the user has navigated back), and set up event handlers to keep
    * the reveal in sync with the radio state.
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.mjs b/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.mjs
index 0fe255c633..b45a912614 100644
--- a/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.mjs
+++ b/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.mjs
@@ -1,5 +1,7 @@
 /**
  * Skip link component
+ *
+ * @preserve
  */
 export class SkipLink {
   /** @private */
@@ -15,7 +17,7 @@ export class SkipLink {
   linkedElementListener = false
 
   /**
-   *
+   * @preserve
    * @param {Element} $module - HTML element to use for skip link
    */
   constructor ($module) {
@@ -28,6 +30,8 @@ export class SkipLink {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs b/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
index 23e726affe..79b0134cd8 100644
--- a/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
+++ b/packages/govuk-frontend/src/govuk/components/tabs/tabs.mjs
@@ -1,5 +1,7 @@
 /**
  * Tabs component
+ *
+ * @preserve
  */
 export class Tabs {
   /** @private */
@@ -33,6 +35,7 @@ export class Tabs {
   mql = null
 
   /**
+   * @preserve
    * @param {Element} $module - HTML element to use for tabs
    */
   constructor ($module) {
@@ -57,6 +60,8 @@ export class Tabs {
 
   /**
    * Initialise component
+   *
+   * @preserve
    */
   init () {
     // Check that required elements are present
diff --git a/packages/govuk-frontend/src/govuk/i18n.mjs b/packages/govuk-frontend/src/govuk/i18n.mjs
index eb922ee142..a3d5d39b7c 100644
--- a/packages/govuk-frontend/src/govuk/i18n.mjs
+++ b/packages/govuk-frontend/src/govuk/i18n.mjs
@@ -2,6 +2,7 @@
  * Internal support for selecting messages to render, with placeholder
  * interpolation and locale-aware number formatting and pluralisation
  *
+ * @preserve
  * @private
  */
 export class I18n {
@@ -9,6 +10,7 @@ export class I18n {
   locale
 
   /**
+   * @preserve
    * @param {{ [key: string]: unknown }} translations - Key-value pairs of the translation strings to use.
    * @param {object} [config] - Configuration options for the function.
    * @param {string} [config.locale] - An overriding locale for the PluralRules functionality.