一个小疑点，新手实在弄不出来,代码很清晰简单_ASP.NET

一个小问题，新手实在弄不出来,代码很清晰简单。
以下是html代码

HTML code

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head>    <title>11</title>    <script type="text/javascript" language="javascript">    function getif(txt1)    {        var txt = document.getElementById("txt_1");        txt.value = txt1;    }    </script></head><body>    <iframe style="display:block;" name="hideframe" id="testframe"></iframe>        <div id = "nofri">          <form id = "imageform" method ="post" action= "asp/upload.ashx" enctype ="multipart/form-data" target= "hideframe">            <input type="submit" value="上传"/>            <input type="file" name="file" />            <input type="text" id="txt_1" />            <input type="button" id="btn_1" onclick = "getif()" value = "取值"/>        </form>              </div></body></html>

以下是提交到得一般处理程序，用C#编写

C# code

<%@ WebHandler Language="C#" Class="upload" %>using System;using System.Web;using System.IO;using System.Net;public class upload : IHttpHandler {        public void ProcessRequest (HttpContext context) {        context.Response.ContentType = "text/html";        context.Response.ContentType = "utf-8";        HttpPostedFile file = context.Request.Files["file"];        string newFilename = Guid.NewGuid().ToString();        var extension = Path.GetExtension(file.FileName).ToUpper();        newFilename += extension;        string filepath = string.Empty;        if (SaveAsImg(newFilename, file, context))        {            //context.Response.Write("<div id='tframe'>" + newFilename +  "</div>");              context.Response.Write("<script>parent.getif('" + newFilename + "')</script>");          }        else        {            context.Response.Write("false");        }            }    public bool SaveAsImg(string filename, HttpPostedFile file, HttpContext context)    {        HttpServerUtility server = context.Server;        try        {            string filepath = server.MapPath("~/img/userimg/" + filename);            file.SaveAs(filepath);            return true;        }        catch        {            return false;        }    }     public bool IsReusable {        get {            return false;        }    }}

问题是，在chrome、FF等内核的浏览器下，该段代码都能达到预期效果。从upload.ashx中取得文件名。
但ie下，iframe直接将返回的代码显示<script>parent.getif('" + newFilename + "')</script>

------解决方案--------------------------------------------------------

探讨
2楼，在chrome和ff中还是正常的，但是ie下，加什么都是直接显示在iframe中。

3楼，改了这句也一样。