var myObject = {
  "myprop1":"value",
  "myprop2":"second",
  "myMethod": function(params) {
    this.myprop1 = params[0];
  }
}
var my_instance = new myObject();
script.log(my_instance.myprop1);
my_instance.mymethod(["test","one","two"]);
script.log(my_instance.myprop1);