js处理字符串转数组，数组转字符串

 if(fpids!="") {
            zzdata = fpids.join(",");
        }
        if(fpnames!="") {
            zzname = fpnames.join(",");
        }
        var t = document.getElementById(fid);
        if(t.checked){
            if(zzdata.indexOf(fid)==-1){
                if(zzdata==""){
                    zzdata =  fid;
                    zzname = frpname;
                }else{
                    zzdata+=","+fid;
                    zzname += ","+frpname;
                }
            }
        }else {
            zzdata = zzdata+",";
            zzname = zzname+",";
            fid = fid+',';
            frpname = frpname+',';
            zzdata = zzdata.replace(fid,'');
            zzname = zzname.replace(frpname,'');
        }
        if(zzdata.charAt(zzdata.length-1)==","){//判断最后一位是否是逗号
            zzdata= zzdata.substring(0,zzdata.length-1);
        }
        if(zzname.charAt(zzname.length-1)==","){//判断最后一位是否是逗号
            zzname= zzname.substring(0,zzname.length-1);
        }
        fpids=zzdata.split(",");
        fpnames=zzname.split(",");