proto_delegation.js

(function(){
  function isForm(element) {
    return element.nodeName.toUpperCase() == 'FORM';
  }

  function isInput(element) {
    var name = element.nodeName.toUpperCase()
    return name == 'INPUT' || name == 'SELECT' || name == 'TEXTAREA';
  }

  var EMULATED_RULES = {
        submit: isForm,
        change: isInput,
        focus:  isInput,
        blur:   isInput
      },
      EMULATED_EVENTS = (function(){
        var element = document.createElement("div");

        // credits to Juriy Zaytsev ( http://thinkweb2.com/projects/prototype/detecting-event-support-without-browser-sniffing/ )
        function isEventSupported(eventName){
          eventName = "on" + eventName;
          if (eventName in element){
            return true;
          }

          element.setAttribute(eventName, "return;");
          return Object.isFunction(element[eventName]);
        }
 
        var events = ['change', 'submit', 'focus', 'blur'].reject(isEventSupported);
      
        element = null;
        return events;
      })();
  
  if (EMULATED_EVENTS.length > 0){
    (function(){
      var emulate = {
        submit: function(){
          function emulateSubmit(e){
              if (this.fire('emulated:submit').returnValue === false){
                e.preventDefault()
              }
          }
          
          document.on('focus', 'form', function(e, element){
            if (element.retrieve('emulated:submit')){
              element.store('emulated:submit', element.on('submit', emulateSubmit));
            }
          });
          
          document.on('blur', 'form', function(e, element){
            var observer = element.retrieve('emulated:submit');
            if (observer){
              observer.stop();
            }
          });
        },
        change: function(){
          var key = 'emulated:change:current_value';
          
          document.on('focus', 'input[type=text],input[type=file],select,textarea', function(e, element){
            element.store(key, element.getValue());
          });

          document.on('blur', 'input[type=text],input[type=file],select,textarea', function(e, element){
            if (element.retrieve(key) != element.getValue()){
              element.fire('emulated:change');
            }
            element.getStorage().unset(key);
          });
        },
        focus:  function(){
          function focusHandler(e){
            e.findElement().fire("emulated:focus");
          }

          if (document.addEventListener){
            document.addEventListener("focus", focusHandler, true);
          } else {
            document.observe("focusin", focusHandler);
          }
        },
        blur:   function(){
          function blurHandler(e){
            e.findElement().fire("emulated:blur");
          }

          if (document.addEventListener){
            document.addEventListener("blur", blurHandler, true);
          } else {
            document.observe("focusout", blurHandler);
          }
        }
      };
      
      EMULATED_EVENTS.each(function(eventName){
        Event.register('emulated' + eventName, emulate[eventName]);
      });
    })();
    
    Event.Handler.prototype.initialize = Event.Handler.prototype.initialize.wrap(function(initialize, element, eventName, selector, callback) {
      element = $(element);
      if (element && selector && EMULATED_EVENTS.indexOf(eventName) > -1 && EMULATED_RULES[eventName](element)){
        eventName = 'emulated:' + eventName;
      }
    
      initialize(element, eventName, selector, callback);
    };
  }
})();