Using JavaScript to implement Gzip compression

Question

Using JavaScript to implement Gzip compression

As I develop a Web application that must save JSON data in a limited server-side cache using AJAX, I am facing the challenge of reducing the stored data size to comply with server quotas. Since I lack control over the server environment, my goal is to gzip the JSON string in the browser before transferring it to the server.

Unfortunately, I have not come across many JavaScript implementations of Gzip for this purpose. Any recommendations on how I can compress the data on the client side prior to uploading it?

javascript ajax compression gzip

Answer 1

Answer №1

Update I recently came across a more efficient LZW solution for handling Unicode strings, which can be found at this website (Credits to pieroxy in the comments).

Although I am not aware of any gzip implementations, there used to be a library called jsolait (the site appears to no longer be available) that offered functions for LZW compression and decompression. The code is licensed under the LGPL.

// Function to compress a string using LZW
function lzw_encode(s) {
    var dict = {};
    var data = (s + "").split("");
    var out = [];
    var currChar;
    var phrase = data[0];
    var code = 256;
    for (var i=1; i<data.length; i++) {
        currChar=data[i];
        if (dict[phrase + currChar] != null) {
            phrase += currChar;
        }
        else {
            out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
            dict[phrase + currChar] = code;
            code++;
            phrase=currChar;
        }
    }
    out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
    for (var i=0; i<out.length; i++) {
        out[i] = String.fromCharCode(out[i]);
    }
    return out.join("");
}

// Function to decompress an LZW-encoded string
function lzw_decode(s) {
    var dict = {};
    var data = (s + "").split("");
    var currChar = data[0];
    var oldPhrase = currChar;
    var out = [currChar];
    var code = 256;
    var phrase;
    for (var i=1; i<data.length; i++) {
        var currCode = data[i].charCodeAt(0);
        if (currCode < 256) {
            phrase = data[i];
        }
        else {
           phrase = dict[currCode] ? dict[currCode] : (oldPhrase + currChar);
        }
        out.push(phrase);
        currChar = phrase.charAt(0);
        dict[code] = oldPhrase + currChar;
        code++;
        oldPhrase = phrase;
    }
    return out.join("");
}

Answer 2

Update I recently came across a more efficient LZW solution for handling Unicode strings, which can be found at this website (Credits to pieroxy in the comments).

Although I am not aware of any gzip implementations, there used to be a library called jsolait (the site appears to no longer be available) that offered functions for LZW compression and decompression. The code is licensed under the LGPL.

// Function to compress a string using LZW
function lzw_encode(s) {
    var dict = {};
    var data = (s + "").split("");
    var out = [];
    var currChar;
    var phrase = data[0];
    var code = 256;
    for (var i=1; i<data.length; i++) {
        currChar=data[i];
        if (dict[phrase + currChar] != null) {
            phrase += currChar;
        }
        else {
            out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
            dict[phrase + currChar] = code;
            code++;
            phrase=currChar;
        }
    }
    out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
    for (var i=0; i<out.length; i++) {
        out[i] = String.fromCharCode(out[i]);
    }
    return out.join("");
}

// Function to decompress an LZW-encoded string
function lzw_decode(s) {
    var dict = {};
    var data = (s + "").split("");
    var currChar = data[0];
    var oldPhrase = currChar;
    var out = [currChar];
    var code = 256;
    var phrase;
    for (var i=1; i<data.length; i++) {
        var currCode = data[i].charCodeAt(0);
        if (currCode < 256) {
            phrase = data[i];
        }
        else {
           phrase = dict[currCode] ? dict[currCode] : (oldPhrase + currChar);
        }
        out.push(phrase);
        currChar = phrase.charAt(0);
        dict[code] = oldPhrase + currChar;
        code++;
        oldPhrase = phrase;
    }
    return out.join("");
}

Answer 3

Answer №2

My recent issue involved the need to decode gzipped data instead of encoding it in gzip format. Since I am executing javascript code outside of a browser environment, I had to figure out how to perform this task using pure javascript.

After some research, I discovered that the JSXGraph library offers a solution for reading gzipped data.

You can access the library and learn more about it from this link: Moreover, there is a standalone utility called JSXCompressor available, which is licensed under LGPL.

To implement decoding of base64 encoded gzipped data in your project, simply include the jsxcompressor.js file:

<!doctype html>
</head>
<title>Test gzip decompression page</title>
<script src="jsxcompressor.js"></script>
</head>
<body>
<script>
    document.write(JXG.decompress('<?php 
        echo base64_encode(gzencode("Try not. Do, or do not. There is no try.")); 
    ?>'));
</script>
</html>

While this may not directly address your original query, I decided to share this information here as I believe it could benefit others facing similar challenges.

Answer 4

My recent issue involved the need to decode gzipped data instead of encoding it in gzip format. Since I am executing javascript code outside of a browser environment, I had to figure out how to perform this task using pure javascript.

After some research, I discovered that the JSXGraph library offers a solution for reading gzipped data.

You can access the library and learn more about it from this link: Moreover, there is a standalone utility called JSXCompressor available, which is licensed under LGPL.

To implement decoding of base64 encoded gzipped data in your project, simply include the jsxcompressor.js file:

<!doctype html>
</head>
<title>Test gzip decompression page</title>
<script src="jsxcompressor.js"></script>
</head>
<body>
<script>
    document.write(JXG.decompress('<?php 
        echo base64_encode(gzencode("Try not. Do, or do not. There is no try.")); 
    ?>'));
</script>
</html>

While this may not directly address your original query, I decided to share this information here as I believe it could benefit others facing similar challenges.

Answer 5

Answer №3

We are thrilled to announce the recent release of pako, a zlib port to JavaScript that can be found at https://github.com/nodeca/pako. This new implementation is believed to be the fastest option for deflate, inflate, gzip, and ungzip operations in JavaScript. Additionally, it boasts a democratic MIT license. Pako fully supports all zlib options and produces binary equal results.

For example:

var inflate = require('pako/lib/inflate').inflate; 
var text = inflate(zipped, {to: 'string'});

Answer 6

We are thrilled to announce the recent release of pako, a zlib port to JavaScript that can be found at https://github.com/nodeca/pako. This new implementation is believed to be the fastest option for deflate, inflate, gzip, and ungzip operations in JavaScript. Additionally, it boasts a democratic MIT license. Pako fully supports all zlib options and produces binary equal results.

For example:

var inflate = require('pako/lib/inflate').inflate; 
var text = inflate(zipped, {to: 'string'});

Answer 7

Answer №4

After transferring an LZMA implementation from a GWT module to standalone JavaScript, I successfully created a tool known as LZMA-JS.

Answer 8

After transferring an LZMA implementation from a GWT module to standalone JavaScript, I successfully created a tool known as LZMA-JS.

Answer 9

Answer №5

Check out these compression algorithms written in JavaScript:

Huffman Coding
LZ77 Compression

Answer 10

Check out these compression algorithms written in JavaScript:

Huffman Coding
LZ77 Compression

Answer 11

Answer №6

Although I haven't personally tried it out, there is a JavaScript tool named JSZip that is meant for ZIP implementation:

Answer 12

Although I haven't personally tried it out, there is a JavaScript tool named JSZip that is meant for ZIP implementation:

Answer 13

Answer №7

Creating a standardized client-side JavaScript compression algorithm seems like it would require a significant amount of processing power compared to simply sending a few extra uncompressed packets over HTTP.

Have you conducted any experiments to determine the potential time savings involved in implementing such a system? Are you primarily focused on conserving bandwidth, or is there another goal driving this consideration?

Answer 14

Creating a standardized client-side JavaScript compression algorithm seems like it would require a significant amount of processing power compared to simply sending a few extra uncompressed packets over HTTP.

Have you conducted any experiments to determine the potential time savings involved in implementing such a system? Are you primarily focused on conserving bandwidth, or is there another goal driving this consideration?

Answer 15

Answer №8

Many modern web browsers have the ability to decompress gzip files as they are being downloaded, making it a preferable choice over utilizing javascript for the same purpose.

Answer 16

Many modern web browsers have the ability to decompress gzip files as they are being downloaded, making it a preferable choice over utilizing javascript for the same purpose.

Answer 17

Answer №9

Utilize a Java applet that compresses images at a 1 pixel per 1 pixel ratio directly on your webpage.

This method requires a Java runtime for clients, as it is not based on JavaScript, but it effectively achieves the desired compression results.

Answer 18

Utilize a Java applet that compresses images at a 1 pixel per 1 pixel ratio directly on your webpage.

This method requires a Java runtime for clients, as it is not based on JavaScript, but it effectively achieves the desired compression results.

Using JavaScript to implement Gzip compression

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

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