example code for comment to blog post: http://evanprodromou.name/2013/02/08/on-using-this-exactly-once/

on-using-this-exactly-once-part-1.js

function Person(/* whatever args your gonna have*/) {
	this.onSave_   = this.onSave.bind( this );
	this.onSetAge_ = this.onSetAge.bind( this );
}

Person.prototype.save = function() {
	this.database.insert( this.properties, this.onSave_ );
};
Person.prototype.setAge = function( newAge ) {
	this.constructor.validate( "age", this, newAge, this.onSetAge_ );
};

Person.prototype.onSave = function( err, result ) {
	if ( err )
		throw err;
		
	this.properties = result;
};
Person.prototype.onSetAge = function( err, result ) {
	if ( err )
		throw err;
	
	this.age = result;
};

on-using-this-exactly-once-part-2.js

;!function( Super ) {
	function ExquisitePerson() {
		Super.apply( this, arguments );
	}
	
	ExquisitePerson.validate = Super.validate;
	
	ExquisitePerson.prototype = Object.create( Super.prototype );
	
	ExquisitePerson.prototype.setAge = function( newAge ) {
		newAge *= .67; // equisite type persons age much more slowly than normal sucker type persons
		Super.prototype.setAge.apply( this, arguments );
	};
	
	ExquisitePerson.prototype.onSave = function( err, result ) {
		Super.prototype.onSave.apply( this, arguments );
		// do something exquisite here to disriminate against normal sucker type persons in favour of equisite type persons
	};
}( Person );

@TryingToImprove I find the best explanations to IIFE in http://benalman.com/news/2010/11/immediately-invoked-function-expression/