diff --git a/strcalc/src/main/frontend/components/init.js b/strcalc/src/main/frontend/components/init.js
index cf12246..a9467b4 100644
--- a/strcalc/src/main/frontend/components/init.js
+++ b/strcalc/src/main/frontend/components/init.js
@@ -17,10 +17,9 @@ import Placeholder from './placeholder'
  *
  * This is a teaching example that contains minimal business logic in order to
  * demonstrate how to design much larger applications for testability.
- * @param {Window} window - the browser window object
- * @param {Document} document - a Document or DocumentFragment
- * @param {Element} appElem - the parent Element containing all app components
+ * @param {object} params - parameters made available to all initializers
+ * @param {Element} params.appElem - parent Element containing all components
  */
-export default function initApp(window, document, appElem) {
-  Placeholder.init(window, document, appElem)
+export default function initApp(params) {
+  [Placeholder].forEach(c => c.init(params))
 }
diff --git a/strcalc/src/main/frontend/components/init.test.js b/strcalc/src/main/frontend/components/init.test.js
index fb075d2..e69adf0 100644
--- a/strcalc/src/main/frontend/components/init.test.js
+++ b/strcalc/src/main/frontend/components/init.test.js
@@ -15,7 +15,7 @@ describe('initial state after calling initApp', () => {
   test('contains the "Hello, World!" placeholder', async () => {
     const page = StringCalculatorPage.new('app-init')
 
-    initApp(window, document, page.appElem, {})
+    initApp({ window, document, appElem: page.appElem })
 
     const e = page.placeholder()
     expect(e.textContent).toContain('Hello, World!')
diff --git a/strcalc/src/main/frontend/components/placeholder.js b/strcalc/src/main/frontend/components/placeholder.js
index 84c5d42..e947fd9 100644
--- a/strcalc/src/main/frontend/components/placeholder.js
+++ b/strcalc/src/main/frontend/components/placeholder.js
@@ -20,11 +20,10 @@ import Template from './placeholder.hbs'
 export default class Placeholder {
   /**
    * Initializes the Placeholder within the document.
-   * @param {Window} window - the browser window object
-   * @param {Document} document - a Document or DocumentFragment
-   * @param {Element} appElem - the parent Element containing all app components
+   * @param {object} params - parameters made available to all initializers
+   * @param {Element} params.appElem - parent Element containing all components
    */
-  static init(window, document, appElem) {
+  static init({ appElem }) {
     appElem.appendChild(Template({
       message: 'Hello, World!',
       url: 'https://en.wikipedia.org/wiki/%22Hello,_World!%22_program'
diff --git a/strcalc/src/main/frontend/main.js b/strcalc/src/main/frontend/main.js
index bba3947..02e663f 100644
--- a/strcalc/src/main/frontend/main.js
+++ b/strcalc/src/main/frontend/main.js
@@ -25,6 +25,11 @@ import initApp from './components/init'
  *   DOMContentLoaded.
  * - init.test.js tests the initApp() method directly.
  */
-document.addEventListener('DOMContentLoaded', () => {
-  initApp(window, document, document.querySelector('#app'))
-})
+document.addEventListener(
+  'DOMContentLoaded',
+  () => {
+    const appElem = document.querySelector('#app')
+    initApp({ appElem })
+  },
+  { once: true }
+)
diff --git a/strcalc/src/main/frontend/test/helpers.js b/strcalc/src/main/frontend/test/helpers.js
index 6656a00..2c08ae3 100644
--- a/strcalc/src/main/frontend/test/helpers.js
+++ b/strcalc/src/main/frontend/test/helpers.js
@@ -10,20 +10,6 @@
  * @module test-helpers
  */
 
-/**
- * Produces a DocumentFragment from an HTML string.
- *
- * Useful for running tests on Document-like objects that don't impact the
- * actual global Document.
- * @param {string} innerHtml - HTML from which to produce a DocumentFragment
- * @returns {DocumentFragment} - DocumentFragment containing innerHtml elements
- */
-export function fragment(innerHtml) {
-  const t = document.createElement('template')
-  t.innerHTML = innerHtml
-  return t.content
-}
-
 /**
  * Enables tests to load page URLs both in the browser and in Node using JSDom.
  */