How to structure javascript objects, while not getting 'undefined' is not a function errors?

Question

If I have a javascript class that runs some initialization code, it seems logical to put this code at the top, and any methods at the bottom of the class. The problem is, if the initialization code contains a method call, I get a 'undefined' is not a function error. I imagine because the method is defined after the method call. How do people normally structure javascript classes to avoid this? Do they put all the initialization code at the end of the class? For example:

var class = function() {
   this.start();
   this.start = function() {
      alert('foo');
   };
};
var object = new class();

causes an error, while:

var class = function() {
   this.start = function() {
      alert('foo');
   };
   this.start();
};
var object = new class();

does not. what would be considered a good structure for a javascript object like this?

Answer 1

Here's what I would do

// create a "namespace"
var com = com || {};
com.domain = com.domain || {};

// add "class" defintion
com.domain.MyClass = function(){
    var privateFields = {};
    var publicFields = {};

    privateFields.myFunction = function(){
        // do something
    }

    publicFields.initialize = function(){ 
        privateFields.myFunction();
    }
    return publicFields;
}

var myClass = new com.domain.MyClass();
myClass.initialize();

of course, you could just make initialize(); "private" and run it before return publicFields;

Answer 2

var class = function() {
   this.start();

};
class.prototype.start = function() {
      alert('foo');
   };

var object = new class();

now you can mess around with start as much as you want in the constructor. but dont use the keyword class as it is a reserved word.