var s = '{"身高":"175cm","性别":"男","兴趣":"唱歌","兴趣":"棒球","兴趣":"游泳"}'
    var kv = {}, m, reg = /"[^"]+":"[^"]+"/gi;
    var m = s.match(reg);

    var o={};
    for(var i=0;i<m.length;i++){
        kv=m[i].match(/"[^"]+"/gi);
         var _arr1=[];;
        for(var j=0;j<kv.length; j++){
            _arr1.push(kv[j].replace(/"/g,''));
        }
        if(_arr1[0] in o){
            if(typeof(o[_arr1[0]])=='string')
            {
                o[_arr1[0]]=[o[_arr1[0]]]
            };
            o[_arr1[0]].push(_arr1[1])
        }else{
            o[_arr1[0]]=_arr1[1]
        }

    }
    console.log(o)//'{"身高":"175cm","性别":"男","兴趣":["唱歌,"棒球","游泳"]}'