Gzip已的JavaScript实现 [英] JavaScript implementation of Gzip

问题描述

我正在写，需要通过AJAX（思来存储JSON数据在一个小的，固定大小的服务器端缓存的Web应用程序：<一href="http://$c$c.google.com/apis/opensocial/articles/persistence-0.8.html#restrictions-quotas">Opensocial配额的）。我没有对服务器的控制。

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.

我需要降低存储的数据留在服务器端配额内的大小，并希望能够将其发送到服务器之前gzip压缩的字符串化的JSON在浏览器中。

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.

不过，我找不到太多的Gzip已对JavaScript实现的方式。对于任何建议，我怎么能融为一体preSS在发送之前在客户端的数据？

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

修改似乎有一个能够正确处理统一code字符串在<一个更好的解决方案，LZW href="http://pieroxy.net/blog/pages/lz-string/index.html">http://pieroxy.net/blog/pages/lz-string/index.html （感谢在评论pieroxy）。

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的实现，但 jsolait库（该网站似乎已经消失）有LZW COM功能pression / DECOM pression。在code是 LGPL 。

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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