How to override "private" function in javascript

Question

I'll explain the problem I'm solving with an example.

I usually define my own libraries in js this way:

window.myLib = (function () {
  var public = {}; // for storing public methods and values
  var private = {}; // for storing private methods and values

  // Atributes and methods here

  return public; // return the public part to be used globally
})();

Now I want to execute an overridable method as a callback from a click event. I would do this:

<input type="checkbox" id="mCheck" onchange="myLib.myMethod()">

Then, in the library I declare the callback "myMethod" that calls another public "overridable" method which I want to use globally, "outside of the library":

  //...
  public.overridable = function(param){console.log("Override this!");};

  public.myMethod = function(){
    if(private.condition) // Just to put some logic
     public.overridable(private.value);
  };
  //...

Here comes the problem. If I redefine the "overridable" method like this:

  myLib.overridable = function(p){console.log(p)};

Then the callback of the click events keeps firing the original "public.override" which outputs the "Override this!" message instead of the value of the parameter.

How can I override the public method to redefine the callback outside the library??

Thanks in advance.

Answer 1

The snippets you've given are already the correct way to do this. If you're having problems it's because of some detail in your implementation - for example, if you store public.overridable in some variable and call it that way instead of referencing public.overridable each time.

I've put together your snippets in a working example below to show that it works exactly as desired.

window.myLib = (function () {
  var public = {}; // for storing public methods and values
  var private = {}; // for storing private methods and values

  // Atributes and methods here
  public.overridable = function(param){console.log("Override this!");};

  public.myMethod = function(){
    if(private.condition) // Just to put some logic
     public.overridable(private.value);
  };

  private.condition = true;
  private.value = "test";

  return public; // return the public part to be used globally
})();

myLib.overridable = function(p){console.log(p)};

<input type="checkbox" id="mCheck" onchange="myLib.myMethod()">