customize template email per party

app/javascript/elements/autoresize_textarea.js

@@ -3,6 +3,8 @@ export default class extends HTMLElement {
     this.resize()
 
     this.textarea.addEventListener('input', () => this.resize())
+
+    this.observeVisibility()
   }
 
   resize () {
@@ -11,6 +13,28 @@ export default class extends HTMLElement {
     }
   }
 
+  observeVisibility () {
+    this.observer = new IntersectionObserver(
+      (entries) => {
+        entries.forEach((entry) => {
+          if (entry.isIntersecting) {
+            this.resize()
+            this.observer.unobserve(this.textarea)
+          }
+        })
+      },
+      {
+        threshold: 0.1
+      }
+    )
+
+    this.observer.observe(this.textarea)
+  }
+
+  disconnectedCallback () {
+    this.observer.unobserve(this.textarea)
+  }
+
   get textarea () {
     return this.querySelector('textarea')
   }