fix(segment-button): protect connectedCallback for when segment-content has not yet been created

core/src/components/segment-button/segment-button.tsx

@@ -67,7 +67,51 @@ export class SegmentButton implements ComponentInterface, ButtonInterface {
     this.updateState();
   }
 
-  connectedCallback() {
+  private getNextSiblingOfType<T extends Element>(element: Element): T | null {
+    let sibling = element.nextSibling;
+    while (sibling) {
+      if (sibling.nodeType === Node.ELEMENT_NODE && (sibling as T) !== null) {
+        return sibling as T;
+      }
+      sibling = sibling.nextSibling;
+    }
+    return null;
+  }
+
+  private waitForSegmentContent(ionSegment: HTMLIonSegmentElement | null, contentId: string): Promise<HTMLElement> {
+    return new Promise((resolve, reject) => {
+      if (!ionSegment) {
+        reject(new Error(`Segment not found when looking for Segment Content`));
+      }
+
+      let timeoutId: any = null;
+      let animationFrameId: number;
+
+      const check = () => {
+        const segmentView = this.getNextSiblingOfType<HTMLIonSegmentViewElement>(ionSegment!); // Skip the text nodes
+        const segmentContent = segmentView?.querySelector(
+          `ion-segment-content[id="${contentId}"]`
+        ) as HTMLIonSegmentContentElement | null;
+        if (segmentContent) {
+          clearTimeout(timeoutId); // Clear the timeout if the segmentContent is found
+          cancelAnimationFrame(animationFrameId);
+          resolve(segmentContent);
+        } else {
+          animationFrameId = requestAnimationFrame(check); // Keep checking on the next animation frame
+        }
+      };
+
+      check();
+
+      // Set a timeout to reject the promise
+      timeoutId = setTimeout(() => {
+        cancelAnimationFrame(animationFrameId);
+        reject(new Error(`Unable to find Segment Content with id="${contentId} within 1000 ms`));
+      }, 1000);
+    });
+  }
+
+  async connectedCallback() {
     const segmentEl = (this.segmentEl = this.el.closest('ion-segment'));
     if (segmentEl) {
       this.updateState();
@@ -78,12 +122,13 @@ export class SegmentButton implements ComponentInterface, ButtonInterface {
     // Return if there is no contentId defined
     if (!this.contentId) return;
 
-    // Attempt to find the Segment Content by its contentId
-    const segmentContent = document.getElementById(this.contentId) as HTMLIonSegmentContentElement | null;
-
-    // If no associated Segment Content exists, log an error and return
-    if (!segmentContent) {
-      console.error(`Segment Button: Unable to find Segment Content with id="${this.contentId}".`);
+    let segmentContent;
+    try {
+      // Attempt to find the Segment Content by its contentId
+      segmentContent = await this.waitForSegmentContent(segmentEl, this.contentId);
+    } catch (error) {
+      // If no associated Segment Content exists, log an error and return
+      console.error('Segment Button: ', (error as Error).message);
       return;
     }
 

core/src/components/segment-view/test/basic/index.html

@@ -123,6 +123,8 @@
         <button class="expand" onClick="changeSegmentContent()">Change Segment Content</button>
 
         <button class="expand" onClick="clearSegmentValue()">Clear Segment Value</button>
+
+        <button class="expand" onClick="addSegmentButtonAndContent()">Add New Segment Button & Content</button>
       </ion-content>
 
       <ion-footer>
@@ -158,6 +160,34 @@
             segment.value = undefined;
           });
         }
+
+        async function addSegmentButtonAndContent() {
+          const segment = document.querySelector('ion-segment');
+          const segmentView = document.querySelector('ion-segment-view');
+
+          const newButton = document.createElement('ion-segment-button');
+          const newId = `new-${Date.now()}`;
+          newButton.setAttribute('content-id', newId);
+          newButton.setAttribute('value', newId);
+          newButton.innerHTML = '<ion-label>New Button</ion-label>';
+
+          segment.appendChild(newButton);
+
+          setTimeout(() => {
+            // Timeout to test waitForSegmentContent() in segment-button
+            const newContent = document.createElement('ion-segment-content');
+            newContent.setAttribute('id', newId);
+            newContent.innerHTML = 'New Content';
+
+            segmentView.appendChild(newContent);
+
+            // Necessary timeout to ensure the value is set after the content is added.
+            // Otherwise, the transition is unsuccessful and the content is not shown.
+            setTimeout(() => {
+              segment.setAttribute('value', newId);
+            }, 200);
+          }, 200);
+        }
       </script>
     </ion-app>
   </body>