how can i update current object in parse.com with javascript?

I found the solution, incase someone needs it later

here it is:

var GameScore = Parse.Object.extend("Driver");
var query = new Parse.Query(GameScore);
query.equalTo("DriverID", "9");
query.first({
  success: function(object) {

     object.set("DName", "aaaa");
    object.save();


  },
  error: function(error) {
    alert("Error: " + error.code + " " + error.message);
  }
});

The difference between the question and your answer may not be obvious at first- So for everyone who has happened here- Use query.first instead of query.find.

query.find()  //don't use this if you are going to try and update an object

returns an array of objects, an array which has no method "set" or "save".

query.first() //use this instead

returns a single backbone style object which has those methods available.