Safe observer attaching

ObserverAttacher.js

function AttachOnce() {
  this.behavior($('.' + this.target_class));
  this.clean();  
}
AttachOnce.prototype.clean = function() {
  $('.' + this.target_class).removeClass(this.target_class);
}
AttachOnce.prototype.behavior = function() {
  // Will be overwritten.
}
AttachOnce.add = function(class_name, target_class, behavior) {
  if(typeof Attach == "undefined") { 
    Attach = {}; 
  }
  Attach[class_name] = function() {
    this.target_class = target_class;
    AttachOnce.call(this);
  }
  Attach[class_name].prototype = AttachOnce.prototype;
  Attach[class_name].prototype = new Attach[class_name]();
  Attach[class_name].prototype.behavior = behavior;
}
	
// Example Attacher
AttachOnce.add('MyObserver', 'js_observer', function(jquery_selector) {
  // Observer code here. Use jquery_selector variable to target elements
});

// Usage
new Attach.MyObserver();