jQuery File Download is a cross server platform compatible jQuery plugin that allows for an Ajax-like file download experience that isn't normally possible using the web.

Demo (of this exact source):

http://jqueryfiledownload.apphb.com/

Source here:

https://github.com/johnculviner/jquery.fileDownload/blob/master/src/Scripts/jquery.fileDownload.js

Targeting pretty modern browser(s)?

This might be a better solution to your problem https://github.com/eligrey/FileSaver.js/

Requirements

jQuery 1.6+

Common questions and answers

Q: I need to send in custom headers. How do I do that?
- Unfortunately since this plugin uses an iframe and not AJAX you cannot send in custom headers. If you really need to do this and are willing to accept a more narrow range of browser support this might be a better solution to your problem https://github.com/eligrey/FileSaver.js/
Q: It doesn't work!?
- Try out the demo and make sure you are doing exactly what it is doing: http://jqueryfiledownload.apphb.com/ If the demo doesn't work in your browser you have defintely found a bug and us know!
- Due to iframe security restrictions you must serve up the file from the same domain you see in the address bar

Supported and tested browsers

Internet Explorer 6+ - Works fine for standard use cases except in < IE9 JavaScript access to the failed response HTML doesn't (and can't) work reliably due to browser iframe constraints.
Firefox 11+ - reasonably sure it will work on earlier versions
Chrome 17+ - reasonably sure it will work on earlier versions
iOS 5.0+ - reasonably sure it will work on earlier versions
Android 4.0+ - non-GET requests do not work due to a long-standing bug in the Android browser. This is handled 'gracefully' with a message to the user.

Note - You must also write a cookie in conjunction with using this plugin as mentioned in the orignal post:

http://johnculviner.com/post/2012/03/22/Ajax-like-feature-rich-file-downloads-with-jQuery-File-Download.aspx

Install

bower install jquery-file-download -S

Example of writing cookie (MVC):

https://github.com/johnculviner/jquery.fileDownload/blob/master/src/Common/FileDownloadAttribute.cs
The above attribute can be used on any controller action that may return a file download that you would like to use jquery.fileDownload.js with

For more information and documentation please visit:

http://johnculviner.com/category/jQuery-File-Download.aspx

Or look at the well documented JavaScript source: