js lzw中文压缩算法

function utf8(){

}

utf8.prototype.encode=function(text)
{
    var result = "";
    for (var n = 0; n < text.length; n++)
    {
        var c = text.charCodeAt(n);
        if (c < 128)
        {
            result += String.fromCharCode(c);
        }
        else if (c > 127 && c < 2048)
        {
            result += String.fromCharCode((c >> 6) | 192);
            result += String.fromCharCode((c & 63) | 128);
        }
        else
        {
            result += String.fromCharCode((c >> 12) | 224);
            result += String.fromCharCode(((c >> 6) & 63) | 128);
            result += String.fromCharCode((c & 63) | 128);
        }
    }
    return result;
}

utf8.prototype.decode=function(text)
{
    var result = "";
    var i = 0;
    var c1 = 0;
    var c2= 0;
    var c3 = 0;
    while (i < text.length)
    {
        c1 = text.charCodeAt(i);
        if (c1 < 128)
        {
            result += String.fromCharCode(c1);
            i++;
        }
        else if (c1 > 191 && c1 < 224)
        {
            c2 = text.charCodeAt(i + 1);
            result += String.fromCharCode(((c1 & 31) << 6) | (c2 & 63));
            i += 2;
        }
        else
        {
            c2 = text.charCodeAt(i + 1);
            c3 = text.charCodeAt(i + 2);
            result += String.fromCharCode(((c1 & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
            i += 3;
        }
    }
    return result;
}

/**
 * Created with JetBrains WebStorm.
 * User: Administrator
 * Date: 12-8-3
 * Time: 下午4:01
 * To change this template use File | Settings | File Templates.
 */
/**
 * lzw中文压缩类
 * @type {*}
 */
function lzwcn(){

}

lzwcn.prototype.compress=function(str){
    var rStr='';
    rStr=as3long.utf8.encode(str);
    var i=0;
    var size=0;
    var xstr='';
    var chars = 256;
    var dict = new Array();
    for (i = 0; i < chars; i++)
    {
        dict[String(i)] = i;
    }
    var splitted=new Array();
    splitted   = rStr.split("");
    var buffer=new Array();
    size=splitted.length;
    var current='';
    var result = new String("");
    for(i = 0;i<=size;i++)
    {
        current = new String(splitted[i]);
        xstr = (buffer.length == 0) ? String(current.charCodeAt(0)) : (buffer.join("-") + "-" + String(current.charCodeAt(0)));
        if (dict[xstr] !== undefined)
        {
            buffer.push(current.charCodeAt(0));
        }
        else
        {
            result += String.fromCharCode(dict[buffer.join("-")]);
            dict[xstr] = chars;
            chars++;
            buffer = new Array();
            buffer.push(current.charCodeAt(0));
        }
    }
    return result;
}

lzwcn.prototype.decompress=function(str){
    var i;
    var chars = 256;
    var dict = new Array();
    for (i = 0; i < chars; i++)
    {
        dict[i] = String.fromCharCode(i);
    }
    var original = new String(str);
    var splitted= original.split("");
    var size = splitted.length;
    var buffer= new String("");
    var chain= new String("");
    var result = new String("");
    for (i = 0; i < size; i++)
    {
        var code = original.charCodeAt(i);
        var current = dict[code];
        if (buffer == "")
        {
            buffer = current;
            result += current;
        }
        else
        {
            if (code <= 255)
            {
                result += current;
                chain = buffer + current;
                dict[chars] = chain;
                chars++;
                buffer = current;
            }
            else
            {
                chain = dict[code];
                if (chain == null)
                {
                    chain = buffer + buffer.slice(0, 1);
                }
                result += chain;
                dict[chars] = buffer + chain.slice(0, 1);
                chars++;
                buffer = chain;
            }
        }
    }
    result = as3long.utf8.decode(result);
    return result;
}

/**
 * Created with JetBrains WebStorm.
 * User: Administrator
 * Date: 12-8-3
 * Time: 下午4:50
 * To change this template use File | Settings | File Templates.
 */
function as3long(){

}

as3long.prototype.lzwcn=new lzwcn();
as3long.prototype.utf8=new utf8();
window.as3long=new as3long();

压缩版下载地址： https://files.cnblogs.com/longhuang/as3long.min.js

使用方法

var str1=as3long.lzwcn.compress("At Microsoft, we've got a long history with email — from Hotmail, our consumer service used by more than 300 million people monthly, to Outlook and Exchange, the software and service managing communications, calendar, and contacts for many millions more.Using the lessons we've learned from both consumers and enterprises, it's our goal to become the very best email service anywhere. That is a big statement – but one we are absolutely committed to deliver upon. That journey starts today.An experience with no compromisesOutlook.com is the first step in creating one complete experience for the next generation of communications. Email should be connected to your friends – whether they like to use Facebook, Twitter, LinkedIn, Google, or a combination. Email should let you get more done, faster – with immediate access to your inbox and tools that can automatically categorize, move, or delete messages you don't want. Email should be deeply integrated with other services – for Outlook.com, you'll find that Office Web Apps, SkyDrive, and, soon, Skype come built right in. And we hope you have already noticed our fast, beautiful user experience. We'd love your feedbackAs we've said before, there is much more to come. If you'd like to follow along in real time, be sure to subscribe to our blog or follow us on Twitter. Along the way, if you've got any questions, comments, or concerns, please submit that feedback via the options menu in our header.Learn more");
var str2=as3long.lzwcn.decompress(str1);

效果：

At Microsoft, we've goāa long historyčith email — fĆm HĕīĭČour cĚsumeĿsņvĄĒuňd bĤmĢĒħan 300 mĭliĚ peoplĒœnħlyČġ Outęok ŗŏExchŗgeůhĒĈĊwarĒŹ ňrŊcũŗagiěŀommunĄatšnsČcaŨndƈČƋŁūactsijĢŝŗŒşƠƱœƉ.UsƕĜħĒŨsĈơčďđĘeƈneŏĴƘŐĕĨƬŃŅrƱƋeūņprğeƢ Ħ'ƱĽĿĔƥ ŰbeŁŅǫƃ đģŐǡāĪĬĮƍƏƊnywƃƻ TžāğŸŐiĜĠƞĪǛāİ“Őų ĚĒĎŸƉŸbĈlųeŭƗƙĦtǎǫo dȡiǴ upĚ.ȄȆ jǧǍĤȍrưȨƨy.AŘexŤǟǛƐĥħ nȩǯǞƘǠsŲŴoŶ.ǯǣƱǁijiǘāĠepǣŘąNjƟƖȗȣŧeȦĩɅņiɈĒfƳɜǍxāƀǍrƞƠȖfȣƚƜƤƟłȳEĺǻhĽlŏǭƗnǍƯȧŰyǧijɇƧƱȒčƃǁĿǁĤŠkŕȩōĒFƮebɖkČTwȥņČLƕʥdInČGɖgŨļĿėǯbƕɾȲ ʉǺƌʌuʎNJāʗuēɭŝŔȪȗČfaɡĿʝʲɋiƙǎiȎŸcƐDŽȨ ˒ĿƕʭxŸƧȨolɛȵƤŘaųƘɾƤlȢʅeĔǟzƁ˖đˁȪȡɭũǡsƓǡˬĽ˘n'āƇūʈʊˌʍʏĒȫɢȢƕȦgɽȦŏˠĨǓņƌʼnŋʜ€ȓɵĿɔŵkɘƘČ˒'̀ɝ˳ŖāOffŋ Wʬ AppǢSkyDǟ̉˲dČĈĚČ͏yŤȣĒbuĭāǟghȇnȳɂ̩Ēʌ͝˒ĝaljƥƉadĤɍƟƐŏʘ˛ĠČǭ˻ƟfˎȯƍɯɆɲnƐȳ͈'ŏęlj˭ijeǎbƮkAƱĎĐƄĬ̴̟̇ʠĒȈƚŽ˖țŰǯeȳIʁ̼Ώiʥ˫ɵ̀owŸęƖƕ ʹĮƟŅͿƄľʦƌuȝąiʐŰʘbęĜƳδęηōȖŘʱʳrͩιǀDzƇŮǣήĽΜēĕ˲ĤquǷƸƣƘŅūǢƳƬƐrơČɬ˜ςbŞā́ΓΕΗdz˥DZĒŦʆdžϮ˓λʘƃ͵ņ.LNjϴΧe||||||789

At Microsoft, we've got a long history with email — from Hotmail, our consumer service used by more than 300 million people monthly, to Outlook and Exchange, the software and service managing communications, calendar, and contacts for many millions more.Using the lessons we've learned from both consumers and enterprises, it's our goal to become the very best email service anywhere. That is a big statement – but one we are absolutely committed to deliver upon. That journey starts today.An experience with no compromisesOutlook.com is the first step in creating one complete experience for the next generation of communications. Email should be connected to your friends – whether they like to use Facebook, Twitter, LinkedIn, Google, or a combination. Email should let you get more done, faster – with immediate access to your inbox and tools that can automatically categorize, move, or delete messages you don't want. Email should be deeply integrated with other services – for Outlook.com, you'll find that Office Web Apps, SkyDrive, and, soon, Skype come built right in. And we hope you have already noticed our fast, beautiful user experience. We'd love your feedbackAs we've said before, there is much more to come. If you'd like to follow along in real time, be sure to subscribe to our blog or follow us on Twitter. Along the way, if you've got any questions, comments, or concerns, please submit that feedback via the options menu in our header.Learn more||||||1467