refactor, use invalid class

app/javascript/elements/visible_on_input.js

@@ -1,14 +0,0 @@
-export default class extends HTMLElement {
-  connectedCallback () {
-    this.input = document.getElementById(this.dataset.inputId)
-
-    this.input.addEventListener('input', () => {
-      if (this.input.value.trim().length > 0) {
-        this.classList.remove('hidden')
-      } else {
-        this.classList.add('hidden')
-        this.querySelectorAll('input').forEach(input => { input.value = '' })
-      }
-    })
-  }
-}