update send modal

app/javascript/elements/toggle_on_checked.js

@@ -0,0 +1,23 @@
+export default class extends HTMLElement {
+  connectedCallback () {
+    this.form.addEventListener('change', this.toggle)
+
+    this.toggle()
+  }
+
+  disconnectedCallback () {
+    this.form.removeEventListener('change', this.toggle)
+  }
+
+  toggle = () => {
+    const selector = this.dataset.names.split(' ').map((name) => `[name="${name}"]:checked:enabled`).join(', ')
+    const isChecked = !!this.form.querySelector(selector)
+
+    this.firstElementChild.classList.toggle('hidden', !isChecked)
+    this.lastElementChild.classList.toggle('hidden', isChecked)
+  }
+
+  get form () {
+    return this.closest('form')
+  }
+}