Downloading files in localstorage

[concealed]

I am intrigued by the drag-upload functionality so that your client-side javascript can have easy access to the bytes of a user's files such as text, image, doc, pdf, xml, etc. However, I have not seen good methods of allowing users to download items in localstorage. Use cases such as allowing a user to "upload" an image, your javascript then edits that image and allows them to download it again, OR maybe upload a doc and the javascript app populates and modifies the doc in a useful way (such as filling in fields).

I've seen the drag to desktop file downloader and think it's neat, but it only works in chrome for now and may not always be as practical was prompting a user to "save as..." I do understand that there is a DATA URI method of directing the user to a url with the base64. (data:image/png;base64,[.......................]), but this doesn't seem to work for all mine/application types across all browsers (think DOC and PDF).

So I was wondering what are the options to allow a user to download a file to disk using modern HTML 5 features (or legacy).

Thanks!

[m0]

Hi concealed,

I think you asked more than one question or if I understood incorrectly

You can "JSONify" localStorage into a string like the following:

Code: Select all

JSON.stringify(localStorage)

And save the entire localStorage (JSON) into disk. The modern way (HTML5) to save a file to disk is by using FileWriter API:
http://www.w3.org/TR/file-writer-api/

It will soon come to Chromium. Very soon.

[concealed]

Hi m0,

Thanks for the reply. What I am really looking for (as an end result) is to allow the user to download the file. This might require sending the file to the server and then back, but I want to try and avoid that.

[zcorpan]

You could use something like <iframe src="data:application/octet-stream,...">. Not ideal since you can't assign a default filename or file type. If a round-trip to the server is acceptable, you can use Content-Disposition: attachment; filename=...

I don't know if FileWriter supports the use case of prompting to save a single file. Maybe it does. If it doesn't, you can send feedback to public-webapps@w3.org with your use case.