Gzip 的 JavaScript 实现 [英] JavaScript implementation of Gzip

问题描述

我正在编写一个 Web 应用程序，它需要通过 AJAX 将 JSON 数据存储在一个小的、固定大小的服务器端缓存中(想想:开放社交配额).我无法控制服务器.

I'm writing a Web application that needs to store JSON data in a small, fixed-size server-side cache via AJAX (think: Opensocial quotas). I do not have control over the server.

我需要减少存储数据的大小以保持在服务器端配额内，并希望能够在将字符串化的 JSON 发送到服务器之前在浏览器中对其进行 gzip.

I need to reduce the size of the stored data to stay within a server-side quota, and was hoping to be able to gzip the stringified JSON in the browser before sending it up to the server.

然而，我在 Gzip 的 JavaScript 实现方面找不到太多的东西.关于如何在发送数据之前在客户端压缩数据的任何建议?

However, I cannot find much in the way of JavaScript implementations of Gzip. Any suggestions for how I can compress the data on the client side before sending it up?

推荐答案

Edit 在 http://pieroxy.net/blog/pages/lz-string/index.html(感谢 pieroxy 在评论中).

Edit There appears to be a better LZW solution that handles Unicode strings correctly at http://pieroxy.net/blog/pages/lz-string/index.html (Thanks to pieroxy in the comments).

我不知道任何 gzip 实现，但是 jsolait 库(该站点似乎已经消失)具有 LZW 压缩/解压功能.该代码包含在 LGPL 下.

I don't know of any gzip implementations, but the jsolait library (the site seems to have gone away) has functions for LZW compression/decompression. The code is covered under the LGPL.

// LZW-compress a string
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("");
}

// 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("");
}

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