eval in page context

public/index.js

@@ -0,0 +1,18 @@
+document.addEventListener('DOMContentLoaded', function () {
+    const button = document.getElementById('btn');
+    button.addEventListener('click', clickHandler);
+});
+
+function clickHandler() {
+    const iframe = document.getElementById('sandbox');
+    iframe.contentWindow.postMessage( "22 * 33", '*');
+
+    function listener(event) {
+        // 这里处理从 iframe 发送回来的数据
+        console.log('Received message:', event.data);
+    }
+
+
+    window.addEventListener('message', listener, {once: true});
+
+}