Generate and download a text file in javascript

Question

All my research so far suggests this can't be done, but I'm hoping someone here has some cunning ideas.

I have a form on a website which allows users to bulk upload lots of URLs to add to a list on the server. There's quite a lot of server-side processing to do on each URL, so to avoid timeouts and to display progress, I've implemented the upload using jQuery to submit the URLs one at a time using ajax.

This is all working nicely. However, part of the processing on each URL is deduplicating it against the complete list. The ajax call returns a status indicating either a successful upload or a rejection due to duplication. As the upload progresses, I tell the user how many URLs have been rejected as duplicates (along with overall progress and ETA).

The problem now is how to give the user a complete list of the failed duplicate URLs. I've kept them in an array in my jQuery, and would like the user to be able to click on a link on the form to download a text file containing those URLs. Is this possible just using client-side processing?

The server-side processing basically handles a single keyword at a time. I'd rather not have to store the duplicates in a database table with some kind of session key which gets sent with every ajax call, and is then used at the end to generate the text file server-side (and then gets cleaned up some time later). I can see how to do this, but it seems very clunky and a bit 20th century.

Answer 1

I haven't used it myself yet, but Downloadify was built for exactly this purpose I think.

Downloadify is a tiny JavaScript + Flash library that enables the generation and saving of files on the fly, in the browser, without server interaction.

It was created by Doug Neiner who is also pretty active on Stack Overflow.

It needs Flash 10 to work.