private fields and methods in JS

privatePublic.js

function MyClass( paramA ) {
   // public member
   this.member = paramA;
   
   // private member, only accessible from the inside
   value1 = 3;
   
   // very private member, only accessible from private and priviliged actors
   var value2 = 6;
   
   // private functions, only accessible from inside
   function say1() {
      alert( value1 );
   };
   function say2() {
      alert ( value2 );
   };
   
   // priviliged function, almighty!
   this.say1212 = function() {
      say1();
      say2();
      alert(value1);
      alert(value2);
   };
};

// attached public function, accessing a public member
MyClass.prototype.getMember = function(){
   return this.member;
};

// attached public function, accessing a private member
MyClass.prototype.getValue1 = function() {
   return value1;
};

// attached public function, hopelessly trying to access a very private member
MyClass.prototype.getValue2 = function() {
   return this.value2;
};


alert( "var m = new MyClass( 'I am new' );" );
var m = new MyClass( "I am new" );

alert( "alert(m.getMember());" );
alert(m.getMember());

alert ( 'm.member = "old old old";' );
m.member = "old old old";

alert ("alert (m.member);");
alert (m.member);

alert( "m.getMember() = 'xxx'; => invalid" );
// m.getMember() = "xxx";

alert ( "alert(m.value1);" );
alert(m.value1);

alert( "alert( m.getValue1() );" );
alert( m.getValue1() );

alert( "alert( m.getValue2() );" );
alert( "?..." + m.getValue2() );

alert( "m.say1(); => not a function" );

alert( "m.say1212();" );
m.say1212();

alert( "That's it" );