function date2str(x,y) {

    var z ={y:x.getFullYear(),M:x.getMonth()+1,d:x.getDate(),h:x.getHours(),m:x.getMinutes(),s:x.getSeconds()};

    return y.replace(/(y+|M+|d+|h+|m+|s+)/g,function(v) {return ((v.length>1?"0":"")+eval('z.'+v.slice(-1))).slice(-(v.length>2?v.length:2))});

}

alert(date2str(new Date(),"yy-M-d h:m:s"));

alert(date2str(new Date(),"yyyy-MM-d h:m:s"));