SOURCE

function format(txt,compress){ 
    var indentChar = '    ';   
    if(/^\s*$/.test(txt)){   
        alert('数据为空,无法格式化! ');   
        return;   
    }   
    try{var data=eval('('+txt+')');}   
    catch(e){   
        alert('数据源语法错误,格式化失败! 错误信息: '+e.description,'err');   
        return;   
    };   
    var draw=[],last=false,This=this,line=compress?'':'\n',nodeCount=0,maxDepth=0;   
        
    var notify=function(name,value,isLast,indent/*缩进*/,formObj){   
        nodeCount++;/*节点计数*/  
        for (var i=0,tab='';i<indent;i++ )tab+=indentChar;/* 缩进HTML */  
        tab=compress?'':tab;/*压缩模式忽略缩进*/  
        maxDepth=++indent;/*缩进递增并记录*/  
        if(value&&value.constructor==Array){/*处理数组*/  
            draw.push(tab+(formObj?('"'+name+'":'):'')+'['+line);/*缩进'[' 然后换行*/  
            for (var i=0;i<value.length;i++)   
                notify(i,value[i],i==value.length-1,indent,false);   
            draw.push(tab+']'+(isLast?line:(','+line)));/*缩进']'换行,若非尾元素则添加逗号*/  
        }else   if(value&&typeof value=='object'){/*处理对象*/  
                draw.push(tab+(formObj?('"'+name+'":'):'')+'{'+line);/*缩进'{' 然后换行*/  
                var len=0,i=0;   
                for(var key in value)len++;   
                for(var key in value)notify(key,value[key],++i==len,indent,true);   
                draw.push(tab+'}'+(isLast?line:(','+line)));/*缩进'}'换行,若非尾元素则添加逗号*/  
            }else{   
                    if(typeof value=='string')value='"'+value+'"';   
                    draw.push(tab+(formObj?('"'+name+'":'):'')+value+(isLast?'':',')+line);   
            };   
    };   
    var isLast=true,indent=0;   
    notify('',data,isLast,indent,false);   
    return draw.join('');   
}
var jsonData = {
    "msg_id": "5I02W-16-8278a",
    "timestamp": 1403099033211,
    "direction":"outgoing",
    "to": "1402541206787",
    "from": "1402541206787",
    "chat_type": "chat",
    "payload": {
    "bodies": [
    {
    "file_length": 58103,
    "filename": "1418105136313.mp4",
    "length": 10,
    "secret": "VfEpSmSvEeS7yU8dwa9rAQc-DIL2HhmpujTNfSTsrDt6eNb_",
    "size":{"height":480,"width":360},
    "thumb": "https://a1.easemob.com/easemob-demo/chatdemoui/chatfiles/67279b20-7f69-11e4-8eee-21d3334b3a97",
    "thumb_secret": "ZyebKn9pEeSSfY03ROk7ND24zUf74s7HpPN1oMV-1JxN2O2I",
    "type": "video",
    "url": "https://a1.easemob.com/easemob-demo/chatdemoui/chatfiles/671dfe30-7f69-11e4-ba67-8fef0d502f46"
    },
    {
    "file_length": 58103,
    "filename": "1418105136313.mp4",
    "length": 10,
    "secret": "VfEpSmSvEeS7yU8dwa9rAQc-DIL2HhmpujTNfSTsrDt6eNb_",
    "size":{"height":480,"width":360},
    "thumb": "https://a1.easemob.com/easemob-demo/chatdemoui/chatfiles/67279b20-7f69-11e4-8eee-21d3334b3a97",
    "thumb_secret": "ZyebKn9pEeSSfY03ROk7ND24zUf74s7HpPN1oMV-1JxN2O2I",
    "type": "video",
    "url": "https://a1.easemob.com/easemob-demo/chatdemoui/chatfiles/671dfe30-7f69-11e4-ba67-8fef0d502f46"
    }
    ],
    "ext": {
    "key1": "value1",
    },
    "from":"1402541206787",
    "to":"1402541206787"
    }
    };
var jsonStr = JSON.stringify(jsonData);
console.info("json text:"+jsonStr+";length:"+jsonStr.length);
var compressed = LZString.compress(jsonStr);
console.info(compressed+" compressed length:"+compressed.length);
var string = LZString.decompress(compressed);
console.info("decompresed is: " + string);
var compressed1 = format(jsonStr,true);
console.info(compressed1+" compressed1 length:"+compressed.length);