Unable to download csv file even though content coming in response header - ajax

Question

I have this stupid problem that I am seeing my csv data in the response header but it's not downloading the csv.
On client side, I have a button and on it's click an ajax post request is fired like
$.ajax({
url: 'xyz/GenerateCSV',
type: 'POST',
data: postData,
contentType: "application/json; charset=utf-8"
});
On the server side I have set Response as
Response.AddHeader("content-disposition", "attachment;filename=ListExport.csv");
Response.ContentType = "text/csv";
The http response header is coming fine as -
Cache-Control:private
content-disposition:attachment;filename=EncounterListExport.csv
Content-Encoding:gzip
Content-Type:text/csv; charset=utf-8
Date:Mon, 22 Sep 2014 14:18:05 GMT
Server:Microsoft-IIS/8.0
Transfer-Encoding:chunked
Vary:Accept-Encoding
X-AspNet-Version:4.0.30319
X-AspNetMvc-Version:4.0
X-Powered-By:ASP.NET
X-SourceFiles:=?UTF-8?B?
Any idea what's going on? I did not make use of any Form or 'submit' button.
Thanks,
Vaibhav

Answer 1

Regarding your comment above:
It fails in the sense that nothing happens.
That's kind of incorrect. By your own admission, "Response content has data." Therefore something does happen. The response sends the data to the client.
The question is, what do you do with that data? According to your code, nothing:
$.ajax({
url: 'xyz/GenerateCSV',
type: 'POST',
data: postData,
contentType: "application/json; charset=utf-8"
});
Look at the documentation for $.ajax(). You need to provide it with some code to invoke after the response is received. That code would handle the response in some way. Something like this:
$.ajax({
url: 'xyz/GenerateCSV',
type: 'POST',
data: postData,
contentType: "application/json; charset=utf-8"
}).done(function (response) {
// use the data from the response
}).fail(function (response) {
// handle an error from the response
});
What you do with that data is up to you. It's structured CSV data, I imagine there exists some JavaScript library out there which can parse that easily. If you want to save the data to a file then you're going to have to prompt the user in some way (which could involve some trickery and workarounds) or save it to local storage. JavaScript can't write directly to the file system (for obvious security reasons).