Use python zlib to decompress string compressed with javascript zlib

Question

On the client side, I use the zlib.js library to deflate some string, then I encode it into base64 to be sent to the server:

var a = {"foo" : "bar"};
var deflate = new Zlib.Deflate(JSON.stringify(a));
var compressed = deflate.compress();
var sentToServer = btoa(String.fromCharCode.apply(null, compressed));
>>> "eJwVwwEJAAAAgKD/ry3B5QAdegQ0"

On the server side I want to use zlib for python27 to decompress, but I got the following error:

import base64, zlib

a = base64.b4decode("eJwVwwEJAAAAgKD/ry3B5QAdegQ0")
zlib.decompress(a)
>>>zlib.error: Error -3 while decompressing data: invalid distance too far back

What is the proper way to achieve that?

georgexsh · Accepted Answer · 2017-09-25 14:00:09Z

1

zlib.js's Deflate accepts Array.<number> orUint8Array, you need convert JSON to an array of int:

var a = {"foo" : "bar"};
var s = JSON.stringify(a);
var data = new Array(s.length);
for (i = 0, il = s.length; i < il; ++i) {
    data[i] = s.charCodeAt(i);
}
var deflate = new Zlib.Deflate(data);

which yields: eJwFgEEJAAAIA7tcDNvow+/A77D7MCtRTB8fHXoENA==

edited Sep 25, 2017 at 14:00

answered Sep 25, 2017 at 13:54

georgexsh

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