prototype/src/event.js

if (!window.Event) var Event = { };

Object.extend(Event, {
  KEY_BACKSPACE: 8,
  KEY_TAB:       9,
  KEY_RETURN:   13,
  KEY_ESC:      27,
  KEY_LEFT:     37,
  KEY_UP:       38,
  KEY_RIGHT:    39,
  KEY_DOWN:     40,
  KEY_DELETE:   46,
  KEY_HOME:     36,
  KEY_END:      35,
  KEY_PAGEUP:   33,
  KEY_PAGEDOWN: 34,
  KEY_INSERT:   45,
  
  cache: { },

  relatedTarget: function(event) {
    var element;
    switch(event.type) {
      case 'mouseover': element = event.fromElement; break;
      case 'mouseout':  element = event.toElement;   break;
      default: return null;
    }
    return Element.extend(element);
  }
});

Event.Methods = (function() {
  var isButton;

  if (Prototype.Browser.IE) {
    var buttonMap = { 0: 1, 1: 4, 2: 2 };
    isButton = function(event, code) {
      return event.button == buttonMap[code];
    };
    
  } else if (Prototype.Browser.WebKit) {
    isButton = function(event, code) {
      switch (code) {
        case 0: return event.which == 1 && !event.metaKey;
        case 1: return event.which == 1 && event.metaKey;
        default: return false;
      }
    };
    
  } else {
    isButton = function(event, code) {
      return event.which ? (event.which === code + 1) : (event.button === code);
    };
  }

  return {
    isLeftClick:   function(event) { return isButton(event, 0) },
    isMiddleClick: function(event) { return isButton(event, 1) },
    isRightClick:  function(event) { return isButton(event, 2) },
    
    element: function(event) {
      event = Event.extend(event);
      
      var node = event.target, type = event.type;
      
      if (event.currentTarget && event.currentTarget.tagName) {
        // Firefox screws up the "click" event when moving between radio buttons
        // via arrow keys. It also screws up the "load" and "error" events on images,
        // reporting the document as the target instead of the original image.
        var currentTarget = event.currentTarget;
        var tagName = currentTarget.tagName.toUpperCase();
        if (['load', 'error'].include(type) ||
         (tagName === 'INPUT' && currentTarget.type === 'radio' && type === 'click'))
          node = currentTarget;
      }
      
      return Element.extend(node && node.nodeType == Node.TEXT_NODE ?
       node.parentNode : node);
    },

    findElement: function(event, expression) {
      var element = Event.element(event);
      if (!expression) return element;
      var elements = [element].concat(element.ancestors());
      return Selector.findElement(elements, expression, 0);
    },

    pointer: function(event) {
      var docElement = document.documentElement, body = document.body;
      return {
        x: event.pageX || (event.clientX + 
          (docElement.scrollLeft || body.scrollLeft) -
          (docElement.clientLeft || 0)),
        y: event.pageY || (event.clientY + 
          (docElement.scrollTop || body.scrollTop) -
          (docElement.clientTop || 0))
      };
    },

    pointerX: function(event) { return Event.pointer(event).x },
    pointerY: function(event) { return Event.pointer(event).y },

    stop: function(event) {
      Event.extend(event);
      event.preventDefault();
      event.stopPropagation();
      event.stopped = true;
    }
  };
})();

Event.extend = (function() {
  var methods = Object.keys(Event.Methods).inject({ }, function(m, name) {
    m[name] = Event.Methods[name].methodize();
    return m;
  });
  
  if (Prototype.Browser.IE) {
    Object.extend(methods, {
      stopPropagation: function() { this.cancelBubble = true },
      preventDefault:  function() { this.returnValue = false },
      inspect: function() { return "[object Event]" }
    });

    return function(event) {
      if (!event) return false;
      if (event._extendedByPrototype) return event;
      
      event._extendedByPrototype = Prototype.emptyFunction;
      var pointer = Event.pointer(event);
      Object.extend(event, {
        target: event.srcElement,
        relatedTarget: Event.relatedTarget(event),
        pageX:  pointer.x,
        pageY:  pointer.y
      });
      return Object.extend(event, methods);
    };
    
  } else {
    Event.prototype = Event.prototype || document.createEvent("HTMLEvents").__proto__;
    Object.extend(Event.prototype, methods);
    return Prototype.K;
  }
})();

Object.extend(Event, (function() {
  var cache = Event.cache;

  function getEventID(element) {
    if (element._prototypeEventID) return element._prototypeEventID[0];
    arguments.callee.id = arguments.callee.id || 1;
    return element._prototypeEventID = [++arguments.callee.id];
  }
  
  function getDOMEventName(eventName) {
    if (eventName && eventName.include(':')) return "dataavailable";
    return eventName;
  }
  
  function getCacheForID(id) {
    return cache[id] = cache[id] || { };
  }
  
  function getWrappersForEventName(id, eventName) {
    var c = getCacheForID(id);
    return c[eventName] = c[eventName] || [];
  }
  
  function createWrapper(element, eventName, handler) {
    var id = getEventID(element);
    var c = getWrappersForEventName(id, eventName);
    if (c.pluck("handler").include(handler)) return false;
    
    var wrapper = function(event) {
      if (!Event || !Event.extend ||
        (event.eventName && event.eventName != eventName))
          return false;
      
      Event.extend(event);
      handler.call(element, event);
    };
    
    wrapper.handler = handler;
    c.push(wrapper);
    return wrapper;
  }
  
  function findWrapper(id, eventName, handler) {
    var c = getWrappersForEventName(id, eventName);
    return c.find(function(wrapper) { return wrapper.handler == handler });
  }
  
  function destroyWrapper(id, eventName, handler) {
    var c = getCacheForID(id);
    if (!c[eventName]) return false;
    c[eventName] = c[eventName].without(findWrapper(id, eventName, handler));
  }
  
  function destroyCache() {
    for (var id in cache)
      for (var eventName in cache[id])
        cache[id][eventName] = null;
  }
  
  
  // Internet Explorer needs to remove event handlers on page unload
  // in order to avoid memory leaks.
  if (window.attachEvent) {
    window.attachEvent("onunload", destroyCache);
  }
  
  // Safari has a dummy event handler on page unload so that it won't
  // use its bfcache. Safari <= 3.1 has an issue with restoring the "document"
  // object when page is returned to via the back button using its bfcache.
  if (Prototype.Browser.WebKit) {    
    window.addEventListener('unload', Prototype.emptyFunction, false);
  }
    
  return {
    observe: function(element, eventName, handler) {
      element = $(element);
      var name = getDOMEventName(eventName);
      
      var wrapper = createWrapper(element, eventName, handler);
      if (!wrapper) return element;
      
      if (element.addEventListener) {
        element.addEventListener(name, wrapper, false);
      } else {
        element.attachEvent("on" + name, wrapper);
      }
      
      return element;
    },
  
    stopObserving: function(element, eventName, handler) {
      element = $(element);
      var id = getEventID(element), name = getDOMEventName(eventName);
      
      if (!handler && eventName) {
        getWrappersForEventName(id, eventName).each(function(wrapper) {
          element.stopObserving(eventName, wrapper.handler);
        });
        return element;
        
      } else if (!eventName) {
        Object.keys(getCacheForID(id)).each(function(eventName) {
          element.stopObserving(eventName);
        });
        return element;
      }
      
      var wrapper = findWrapper(id, eventName, handler);
      if (!wrapper) return element;
      
      if (element.removeEventListener) {
        element.removeEventListener(name, wrapper, false);
      } else {
        element.detachEvent("on" + name, wrapper);
      }
      
      destroyWrapper(id, eventName, handler);
      
      return element;
    },
  
    fire: function(element, eventName, memo) {
      element = $(element);
      if (element == document && document.createEvent && !element.dispatchEvent)
        element = document.documentElement;
        
      var event;
      if (document.createEvent) {
        event = document.createEvent("HTMLEvents");
        event.initEvent("dataavailable", true, true);
      } else {
        event = document.createEventObject();
        event.eventType = "ondataavailable";
      }

      event.eventName = eventName;
      event.memo = memo || { };

      if (document.createEvent) {
        element.dispatchEvent(event);
      } else {
        element.fireEvent(event.eventType, event);
      }

      return Event.extend(event);
    }
  };
})());

Object.extend(Event, Event.Methods);

Element.addMethods({
  fire:          Event.fire,
  observe:       Event.observe,
  stopObserving: Event.stopObserving
});

Object.extend(document, {
  fire:          Element.Methods.fire.methodize(),
  observe:       Element.Methods.observe.methodize(),
  stopObserving: Element.Methods.stopObserving.methodize(),
  loaded:        false
});

(function() {
  /* Support for the DOMContentLoaded event is based on work by Dan Webb, 
     Matthias Miller, Dean Edwards and John Resig. */

  var timer;
  
  function fireContentLoadedEvent() {
    if (document.loaded) return;
    if (timer) window.clearInterval(timer);
    document.fire("dom:loaded");
    document.loaded = true;
  }
  
  if (document.addEventListener) {
    if (Prototype.Browser.WebKit) {
      timer = window.setInterval(function() {
        if (/loaded|complete/.test(document.readyState))
          fireContentLoadedEvent();
      }, 0);
      
      Event.observe(window, "load", fireContentLoadedEvent);
      
    } else {
      document.addEventListener("DOMContentLoaded", 
        fireContentLoadedEvent, false);
    }
    
  } else {
    document.write("<script id=__onDOMContentLoaded defer src=//:><\/script>");
    $("__onDOMContentLoaded").onreadystatechange = function() { 
      if (this.readyState == "complete") {
        this.onreadystatechange = null; 
        fireContentLoadedEvent();
      }
    }; 
  }
})();