UnityWebgl错误-Uncaught DOMException: Blocked a frame with origin "" from accessing a cross-origin frame

一个Web项目，父页面给子页面传递参数，代码如下：

 1 <!DOCTYPE html>
 2 <html lang="en-us">
 3   <head>
 4     <meta charset="utf-8">
 5     <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 6     <title>Unity WebGL Player | JsToUnityToDBDemo</title>
 7     <link rel="shortcut icon" href="TemplateData/favicon.ico">
 8     <link rel="stylesheet" href="TemplateData/style.css">
 9     <script src="TemplateData/UnityProgress.js"></script>
10     <script src="Build/UnityLoader.js"></script>
11     <script>
12       var unityInstance = UnityLoader.instantiate("unityContainer", "Build/webgl.json", {onProgress: UnityProgress});
13       var txt1;
14       window.onload = function () {
15           txt1 = parent.document.getElementById("IDValue");18       }
19       function SayHello(arge)
20       {
21           alert(arge);
22           unityInstance.SendMessage("Main Camera", "Receive", txt1.value);
23       }
24     </script>
25   </head>
26   <body>
27     <div class="webgl-content">
28       <div id="unityContainer" style=" 960px; height: 600px"></div>
29       <div class="footer">
31         <div class="webgl-logo"></div>
32         <div class="fullscreen" onclick="unityInstance.SetFullscreen(1)"></div>
33         <div class="title">JsToUnityToDBDemo</div>
34       </div>
35     </div>
36   </body>
37 </html>

在本地调试时parent.document.getElementById("IDValue")报错，放到服务器上不报错：

Uncaught DOMException: Blocked a frame with origin "" from accessing a cross-origin frame

　通过查资料得知两个页面需要在同一域名下，所以服务器上没有问题。

　补充：

　　iframe嵌套子页面父页面相互取元素和方法（如果有好的可跨域的父与子页面传值的方法，欢迎评论）。

365个夜晚，我希望做到两天更一篇博客。加油，小白！