Accessing private member variables from prototype-defined functions

Question

Is there any way to make “private” variables (those defined in the constructor), available to prototype-defined methods?

TestClass = function(){
    var priv         


        

Answer 1

Yes, it's possible. PPF design pattern just solves this.

PPF stands for Private Prototype Functions. Basic PPF solves these issues:

1. Prototype functions get access to private instance data.
2. Prototype functions can be made private.

For the first, just:

1. Put all private instance variables you want to be accessible from prototype functions inside a separate data container, and
2. Pass a reference to the data container to all prototype functions as a parameter.

It's that simple. For example:

// Helper class to store private data.
function Data() {};

// Object constructor
function Point(x, y)
{
  // container for private vars: all private vars go here
  // we want x, y be changeable via methods only
  var data = new Data;
  data.x = x;
  data.y = y;

  ...
}

// Prototype functions now have access to private instance data
Point.prototype.getX = function(data)
{
  return data.x;
}

Point.prototype.getY = function(data)
{
  return data.y;
}

...

Read the full story here:

PPF Design Pattern