fix ssr for sl-alert and scrollend-polyfill (#2359)

* Fix: Make Alert SSR compatible

* Fix: Make sure polyfill is only called on the frontend

* Add changelog entries

* Removed debug statement

* Changelog adjustments

* Another console.log statement :(

---------

Co-authored-by: Cory LaViska <cory@abeautifulsite.net>

docs/pages/resources/changelog.md

@@ -16,6 +16,8 @@ New versions of Shoelace are released as-needed and generally occur when a criti
 
 - Improved performance of `<sl-select>` when using a large number of options [#2318]
 - Updated the Japanese translation [#2329]
+- Adjust `<sl-alert>` to create the toast stack when used only, making it usable in SSR environments. [#2359]
+- Adjust `scrollend-polyfill` so it only runs on the client to make it usable in SSR environments. [#2359]
 - Fixed a bug with radios in `<sl-dialog>` focus trapping.
 
 ## 2.19.1

src/components/alert/alert.component.ts

@@ -13,8 +13,6 @@ import SlIconButton from '../icon-button/icon-button.component.js';
 import styles from './alert.styles.js';
 import type { CSSResultGroup } from 'lit';
 
-const toastStack = Object.assign(document.createElement('div'), { className: 'sl-toast-stack' });
-
 /**
  * @summary Alerts are used to display important messages inline or as toast notifications.
  * @documentation https://shoelace.style/components/alert
@@ -50,6 +48,17 @@ export default class SlAlert extends ShoelaceElement {
   private readonly hasSlotController = new HasSlotController(this, 'icon', 'suffix');
   private readonly localize = new LocalizeController(this);
 
+  private static currentToastStack: HTMLDivElement;
+
+  private static get toastStack() {
+    if (!this.currentToastStack) {
+      this.currentToastStack = Object.assign(document.createElement('div'), {
+        className: 'sl-toast-stack'
+      });
+    }
+    return this.currentToastStack;
+  }
+
   @query('[part~="base"]') base: HTMLElement;
 
   @query('.alert__countdown-elapsed') countdownElement: HTMLElement;
@@ -195,11 +204,11 @@ export default class SlAlert extends ShoelaceElement {
   async toast() {
     return new Promise<void>(resolve => {
       this.handleCountdownChange();
-      if (toastStack.parentElement === null) {
-        document.body.append(toastStack);
+      if (SlAlert.toastStack.parentElement === null) {
+        document.body.append(SlAlert.toastStack);
       }
 
-      toastStack.appendChild(this);
+      SlAlert.toastStack.appendChild(this);
 
       // Wait for the toast stack to render
       requestAnimationFrame(() => {
@@ -211,12 +220,12 @@ export default class SlAlert extends ShoelaceElement {
       this.addEventListener(
         'sl-after-hide',
         () => {
-          toastStack.removeChild(this);
+          SlAlert.toastStack.removeChild(this);
           resolve();
 
           // Remove the toast stack from the DOM when there are no more alerts
-          if (toastStack.querySelector('sl-alert') === null) {
-            toastStack.remove();
+          if (SlAlert.toastStack.querySelector('sl-alert') === null) {
+            SlAlert.toastStack.remove();
           }
         },
         { once: true }

src/internal/scrollend-polyfill.ts

@@ -26,54 +26,61 @@ const decorate = <T, M extends keyof T>(
   } as MethodOf<T, M>;
 };
 
-const isSupported = 'onscrollend' in window;
+(() => {
+  // SSR environments should not apply the polyfill
+  if (typeof window === 'undefined') {
+    return;
+  }
 
-if (!isSupported) {
-  const pointers = new Set();
-  const scrollHandlers = new WeakMap<EventTarget, EventListenerOrEventListenerObject>();
+  const isSupported = 'onscrollend' in window;
 
-  const handlePointerDown = (event: TouchEvent) => {
-    for (const touch of event.changedTouches) {
-      pointers.add(touch.identifier);
-    }
-  };
+  if (!isSupported) {
+    const pointers = new Set();
+    const scrollHandlers = new WeakMap<EventTarget, EventListenerOrEventListenerObject>();
 
-  const handlePointerUp = (event: TouchEvent) => {
-    for (const touch of event.changedTouches) {
-      pointers.delete(touch.identifier);
-    }
-  };
-
-  document.addEventListener('touchstart', handlePointerDown, true);
-  document.addEventListener('touchend', handlePointerUp, true);
-  document.addEventListener('touchcancel', handlePointerUp, true);
-
-  decorate(EventTarget.prototype, 'addEventListener', function (this: EventTarget, addEventListener, type) {
-    if (type !== 'scrollend') return;
-
-    const handleScrollEnd = debounce(() => {
-      if (!pointers.size) {
-        // If no pointer is active in the scroll area then the scroll has ended
-        this.dispatchEvent(new Event('scrollend'));
-      } else {
-        // otherwise let's wait a bit more
-        handleScrollEnd();
+    const handlePointerDown = (event: TouchEvent) => {
+      for (const touch of event.changedTouches) {
+        pointers.add(touch.identifier);
       }
-    }, 100);
+    };
 
-    addEventListener.call(this, 'scroll', handleScrollEnd, { passive: true });
-    scrollHandlers.set(this, handleScrollEnd);
-  });
+    const handlePointerUp = (event: TouchEvent) => {
+      for (const touch of event.changedTouches) {
+        pointers.delete(touch.identifier);
+      }
+    };
 
-  decorate(EventTarget.prototype, 'removeEventListener', function (this: EventTarget, removeEventListener, type) {
-    if (type !== 'scrollend') return;
+    document.addEventListener('touchstart', handlePointerDown, true);
+    document.addEventListener('touchend', handlePointerUp, true);
+    document.addEventListener('touchcancel', handlePointerUp, true);
 
-    const scrollHandler = scrollHandlers.get(this);
-    if (scrollHandler) {
-      removeEventListener.call(this, 'scroll', scrollHandler, { passive: true } as unknown as EventListenerOptions);
-    }
-  });
-}
+    decorate(EventTarget.prototype, 'addEventListener', function (this: EventTarget, addEventListener, type) {
+      if (type !== 'scrollend') return;
+
+      const handleScrollEnd = debounce(() => {
+        if (!pointers.size) {
+          // If no pointer is active in the scroll area then the scroll has ended
+          this.dispatchEvent(new Event('scrollend'));
+        } else {
+          // otherwise let's wait a bit more
+          handleScrollEnd();
+        }
+      }, 100);
+
+      addEventListener.call(this, 'scroll', handleScrollEnd, { passive: true });
+      scrollHandlers.set(this, handleScrollEnd);
+    });
+
+    decorate(EventTarget.prototype, 'removeEventListener', function (this: EventTarget, removeEventListener, type) {
+      if (type !== 'scrollend') return;
+
+      const scrollHandler = scrollHandlers.get(this);
+      if (scrollHandler) {
+        removeEventListener.call(this, 'scroll', scrollHandler, { passive: true } as unknown as EventListenerOptions);
+      }
+    });
+  }
+})();
 
 // Without an import or export, TypeScript sees vars in this file as global
 export {};