diff --git a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html
index 8e936532d1aac7..ce171bfb8e10f9 100644
--- a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html
+++ b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-1.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<meta charset="uft-8">
+<meta charset="utf-8">
 <title>iframe sandbox without allow_modals (alert)</title>
 <link rel="author" title="Igalia" href="https://www.igalia.com/">
 <link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
@@ -7,23 +7,7 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
 <script>
-    let modalName = "alert";
-    let expectedValue = undefined;
-
-    let timeOutForFailingToOpenModal = 500;
-    let startTime;
-    async_test(t => {
-        let iframe = document.querySelector("iframe");
-        iframe.onload = function() {
-            window.addEventListener("message", t.step_func_done(e => {
-                e.source.close();
-                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
-                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
-            }));
-            startTime = new Date().getTime();
-            iframe.contentWindow.postMessage(modalName, "*");
-        }
-        iframe.src = "support/iframe-that-opens-modals.html";
-    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+    runTest("alert", undefined);
 </script>
diff --git a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html
index 5fd47be01ac4ab..fbd4d23d015c88 100644
--- a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html
+++ b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-2.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<meta charset="uft-8">
+<meta charset="utf-8">
 <title>iframe sandbox without allow_modals (confirm)</title>
 <link rel="author" title="Igalia" href="https://www.igalia.com/">
 <link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
@@ -7,23 +7,7 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
 <script>
-    let modalName = "confirm";
-    let expectedValue = false;
-
-    let timeOutForFailingToOpenModal = 500;
-    let startTime;
-    async_test(t => {
-        let iframe = document.querySelector("iframe");
-        iframe.onload = function() {
-            window.addEventListener("message", t.step_func_done(e => {
-                e.source.close();
-                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
-                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
-            }));
-            startTime = new Date().getTime();
-            iframe.contentWindow.postMessage(modalName, "*");
-        }
-        iframe.src = "support/iframe-that-opens-modals.html";
-    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+    runTest("confirm", false);
 </script>
diff --git a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html
index 992f4bafcad21f..57123011807589 100644
--- a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html
+++ b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-3.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<meta charset="uft-8">
+<meta charset="utf-8">
 <title>iframe sandbox without allow_modals (prompt)</title>
 <link rel="author" title="Igalia" href="https://www.igalia.com/">
 <link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
@@ -7,23 +7,7 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
 <script>
-    let modalName = "prompt";
-    let expectedValue = null;
-
-    let timeOutForFailingToOpenModal = 500;
-    let startTime;
-    async_test(t => {
-        let iframe = document.querySelector("iframe");
-        iframe.onload = function() {
-            window.addEventListener("message", t.step_func_done(e => {
-                e.source.close();
-                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
-                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
-            }));
-            startTime = new Date().getTime();
-            iframe.contentWindow.postMessage(modalName, "*");
-        }
-        iframe.src = "support/iframe-that-opens-modals.html";
-    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+    runTest("prompt", null);
 </script>
diff --git a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html
index 8e1cbc4d76ea0e..f750e345ea338d 100644
--- a/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html
+++ b/html/semantics/embedded-content/the-iframe-element/iframe_sandbox_block_modals-4.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<meta charset="uft-8">
+<meta charset="utf-8">
 <title>iframe sandbox without allow_modals (print)</title>
 <link rel="author" title="Igalia" href="https://www.igalia.com/">
 <link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
@@ -7,23 +7,7 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <iframe sandbox="allow-scripts"></iframe>
+<script src="support/iframe_sandbox_block_modals.js"></script>
 <script>
-    let modalName = "print";
-    let expectedValue = undefined;
-
-    let timeOutForFailingToOpenModal = 500;
-    let startTime;
-    async_test(t => {
-        let iframe = document.querySelector("iframe");
-        iframe.onload = function() {
-            window.addEventListener("message", t.step_func_done(e => {
-                e.source.close();
-                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
-                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
-            }));
-            startTime = new Date().getTime();
-            iframe.contentWindow.postMessage(modalName, "*");
-        }
-        iframe.src = "support/iframe-that-opens-modals.html";
-    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+    runTest("print", undefined);
 </script>
diff --git a/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js b/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js
new file mode 100644
index 00000000000000..50e0ca51d61c8e
--- /dev/null
+++ b/html/semantics/embedded-content/the-iframe-element/support/iframe_sandbox_block_modals.js
@@ -0,0 +1,17 @@
+function runTest(modalName, expectedValue) {
+    let timeOutForFailingToOpenModal = 500;
+    let startTime;
+    async_test(t => {
+        let iframe = document.querySelector("iframe");
+        iframe.onload = function() {
+            window.addEventListener("message", t.step_func_done(e => {
+                e.source.close();
+                assert_less_than(new Date().getTime() - startTime, timeOutForFailingToOpenModal, "Call to open modal dialog did not return immediately");
+                assert_equals(e.data, expectedValue, "Call to open modal dialog did not return expected value");
+            }));
+            startTime = new Date().getTime();
+            iframe.contentWindow.postMessage(modalName, "*");
+         }
+        iframe.src = "support/iframe-that-opens-modals.html";
+    }, "Frames without `allow-modals` should not be able to open modal dialogs");
+}
