javascript compression algorithm that supports BINARY data?

Question

I'm looking for a lossless compression algorithm (like LZW or Huffman or anything) in javascript, that accepts and returns raw, binary data.

With 'binary data' I mean a sequence of bytes, which may come in any of the following forms:

• a string containing characters with any value from 0 to 255
• an array containing integers with any value from 0 to 255
• a string containing a hexadecimal representation of the data (i.e. 2 hex digits per byte)
• a string containing the base64 encoded representation of the data
• or anything else that can be unambiguously converted from or to any of the above

Now obviously there are TONS of javascript implementations available everywhere, for a wide range of algorithms. However EVERYTHING I find seems to do crazy stuff like:

• returning an array containing also values >255 (so what is the compression ratio now? how do I represent this in bytes, or how would I go about saving this to a file for example?)

• messing with character encodings in strings, converting from/to unicode or url/html entities or whatnot (it's BINARY, character encoding does not apply here!)

• return other representations that don't seem suitable for binary storage (i.e. cannot be converted to sequence of bytes)

Would anyone know of a good javascript compression (+decompression) implementation that suits my binary fetish?

Answer 1

I think I found what I was looking for after all: this deflate + inflate implementation in javascript seems to work with strings as byte sequences.

Answer 2

first of all create a closure for hold the binar or hex or decimal flags

function ASearch() { }
ASearch.Flag = {
    Front_Wheel_Drive: 0xF, Rear_Wheel_Drive: 0xF0, Four_Wheel_Drive: 0xF00,
    Auto: 0xFF, Manual: 0xFF00,
    Gas: 0xF, Diesel: 0xF0, Hybrid: 0xF00, Electrical: 0xF000,
    Two: 1, Three: 2, Four: 4, Five: 8, Six: 16, Eight: 32, Ten: 64, Twelve: 128
};

then set like this

SetFlag = (function (e) {
   e = e.srcElement;
   $("#" + e.parentNode.name).val(e.checked ?
        $("#" + e.parentNode.name).val() | ASearch.Flag[e.id] :
        $("#" + e.parentNode.name).val() ^ ASearch.Flag[e.id]);
});

this is an example for packed data in a 32 bit integer

there are four variable... i've used them for 18 flags.. this is fast and super effective

for example...

int i = 0; //binary = 0000 0000 0000 0000

i = i | 255; //binary = 0000 0000 1111 1111

i = i ^ 255; //binary = 0000 0000 0000 0000

i = i | 0xFF00; //binary = 1111 1111 0000 0000

i = i | 255; //binary = 1111 1111 1111 1111

i = i ^ 0xFF00; //binary = 0000 0000 1111 1111