How to save a png from javascript variable

Question

I have an image encoded in base64 in a javascript variable : data:image/png;base64, base64 data

[EDIT] I need to save that file to disk without asking to the visitor to do a right click [/EDIT]

Is it possible ? How ?

Thanks in advance

Best regards

Answer 1

You can't. You can read this post.

Answer 2

... without asking to the visitor anyhing ... Is it possible?

No, that would have been a security hole. If it was possible, one would be able to write malware to the enduser's disk unaskingly. Your best bet may be a (signed) Java Applet. True, it costs a bit of $$$ to get it signed (so that it doesn't pop security warnings), but it is able to write data to enduser's disk without its permission.

Answer 3

It's not possible.

If it was, browsers would be massively insecure, being able to write random data to your hard disk without user interaction.

Answer 4

I think it's possible with JavaScript if you use ActiveX.

Another possibility is to make the server spit out that file with a different mime type so the browser asks the user to save it.

Answer 5

with javascript, you can't. the only real possibility i can think of will be a java-applet, but maybe (i don't know how long that image should be saved) you could simply add an img-tag with you png and force caching (but if the user deletes his cache, the image will be gone).

Answer 6

As other answers already stated, you cannot do it only with javascript. If you want, you can send the data (using normal HTTP POST) to a PHP script, call header('Content-type: image/png') and output the decoded image data to the page using echo base64_decode($base64data).

This will work just as if user clicked on an image and open it or prompt him to save the file to disk (the normal browser's save file dialog).