Using JavaScript and PHP to download image files and return a zip file

Question

I'm in the middle of developing a Safari extension for imageboard-type websites and one of the bigger features I'm hoping to implement is the ability to download all of the images (the posted ones, not the global page-level images) that had been posted.

There are similar questions here already, but mine differs a bit in that the images in question are hosted on an entirely different server. I've been brainstorming a bit and figured that gathering all of the image URLs in a JS array then sending it to my server to be turned into a zip file (forcing the download, not just a link to the file) would be the best way to go. I also want the zip to be deleted after the user downloads it.

I've already finished the majority of the extension features but this one is stumping me. Any help would be greatly appreciated.

How would I'd go about doing this?

Answer 1

You want a extension to contact your server for downloads? That's a terrible idea! Make the zipfile locally - it's not regular javascript, it's an extension - you have full access.

Anyway assuming you want to do this anyway, what is the trouble you are having? You get a list of urls, send them to your server, your server downloads them, zips them and send them to the user. (The "your server downloads them" part should worry you!)

What problem are you having?

Answer 2

You can use PHP's ZipArchive class to make a ZIP, then stream it to the browser.

<?php
// Create temp zip file
$zip = new ZipArchive;
$temp = tempnam(sys_get_temp_dir(), 'zip');
$zip->open($temp);

// Add files
$zip->addFromString('file.jpg', file_get_contents('http://path/to/file.jpg'));
$zip->addFile('/this/is/my/file.txt');

// Write temp file
$zip->close();

// Stream file to browser
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename=myFile.zip');
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize($temp));

readfile($temp);

unlink($temp);
exit;