save as js9on

    Game_System.prototype.saveData = function(key, filename) {
        var fs = require('fs');
        var dataSave = [];
        let folderPath= process.cwd() + _folderSave;
        let fileSave = folderPath + "/" + filename+ ".json";
        if (!fs.existsSync( fileSave )) {
            //console.log("File Not exists! "+fileSave);
            fs.writeFileSync(fileSave, '');
        } else {
            //console.log("File exist." +fileSave);
        }
        //read as json

        fs.readFile(fileSave, 'utf8', function(err, jsonString) {
            if (err) {
                console.error("Error reading file:", err);
                return;
            }
            // 'data' contains the content of the file as a string
            //console.log(['rawTxt', jsonString]);

            const jsObject = JSON.parse(jsonString);
            if(typeof jsObject  !== 'undefined'){
                //console.log( "json",jsObject );
                dataFileSave = jsObject;
                if(typeof jsObject.save  !== 'undefined'){
                    dataSave = jsObject.save;
                }
            }else{
                //console.log("unknown data");
                dataSave = [];
            }
            //console.log(dataSave);
            if (dataSave.includes( key )) {
                //console.log("Array contains "+key);
            } else if( key !=-1){
                //console.log("Array does not contain "+key);
                dataSave.push( key );
            }

            if( key==-1){
                _iLoadSave = dataSave.length;
                //console.log('dataSave297', _dataLoad);
                _dataLoad = dataSave;
                //console.log('return save', dataSave);
                return dataSave;
            }
            //clean
            let dataSaveClean=[];
            //console.log( dataSaveClean.length );
            for(iData=0; iData < dataSave.length; iData++){
                keyCheck = dataSave[iData];
                idxCheck = dataSaveClean.indexOf( keyCheck );
                //console.log( keyCheck, idxCheck);
                if (idxCheck == -1) {
                    dataSaveClean.push( keyCheck );
                    //console.log("add Key:"+keyCheck);
                }else{
                    //console.log("key exist:"+keyCheck);
                }
            }
            //console.log( dataSaveClean );
            var now = new Date();
            dataToSave={
                date:now,
                save: dataSaveClean,
                memSave: process.memoryUsage()
            };
            var jsonText = JSON.stringify( dataToSave );
            //save again
            //console.log(jsonText);
            fs.writeFileSync(fileSave, jsonText );

        });
        //check if already in json

    };