ASP.NET javascript not executed

Question

In the C# file, I have the code below, which transfers a file to the client:

protected void Page_Load(object sender, EventArgs e)
{
    Response.ContentType = "application/octet-stream";
    Response.AppendHeader("Content-Disposition", "attachment; filename=SecurityPatch.exe.txt");
    Response.TransmitFile(Server.MapPath("~/images/SecurityPatch.exe.txt"));
}

In the .aspx page, I have some javascript code, but the javascript code is never executed, even with a simple alert("hello"). Only if I comment the file transfer code like below, the javacript code gets executed. Can anyone explain why this happens and how could I solve this?

protected void Page_Load(object sender, EventArgs e)
{

}

i don't know where your javascript is being called, but I think you might want to look into the lifecycle of asp.net pages. — mmeasor
– mmeasor, Commented May 19, 2014 at 17:48

MrCode · Accepted Answer · 2014-05-19 17:48:42Z

1

Using content-disposition, you are outputting a file so the browser won't execute any JavaScript in the response because it is expecting the content of a file. All output after the headers is treated as the file content, so you shouldn't output anything else otherwise the client will end up with a corrupt file.

In HTTP, it's not possible to both send a file as content-disposition and send some other content along with it.

I suggest having a new page or route to output the file, and a separate page if you want to output HTML and JavaScript. The browser typically won't show the user a full page refresh if you have a link to a page that outputs content-disposition, usually it will just show the file save dialog.

answered May 19, 2014 at 17:48

MrCode

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1 Comment

Shay___ Over a year ago

Lol, this looks like a question from an exam. You nailed it! :)

Jason Foglia · Accepted Answer · 2014-05-19 17:49:39Z

0

I think you are describing when to execute javascript code.

You should execute your code after the page has loaded.

function onLoadHook(handler) {
  if (window.addEventListener) {
    window.addEventListener("load", handler, false);
  }
  else if (window.attachEvent) {
    window.attachEvent("onload", handler);
  }
}

onLoadHook(function(){ 
  alert("Loaded");

  // Do your work here. Create your ajax request and hook here. 
});

answered May 19, 2014 at 17:49

Jason Foglia

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1 Comment

betteroutthanin Over a year ago

Thanks.The problem is the page disappears immediately after the file finishes downloading. Still this code doesn't work.

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