Hello.
This is a reference file from a book I read in which the core subject is the use of '
event listeners'.
I'm trying to load the file in Firefox and it's giving me an error message:
Line: 5
Char: 1
Error: 'document' is undefined
Code: 800A1391
Source: Microsoft JScript Runtime Error
I need this file to work because it's the reference file for all of my coding. Here's the contents of the file here.
Code:
var Core={};
// W3C DOM 2 Events model
if (document.addEventListener)
{
Core.addEventListener = function(target, type, listener)
{
target.addEventListener (type, listener, false);
};
Core.removeEventListener = function(target, type, listener)
{
target.removeEventListener(type, listener, false);
};
Core.preventDefault = function(event)
{
event.preventDefault();
};
Core.stopPropagation = function(event)
{
event.stopPropagation();
};
}
// Internet Explorer Events model
else if (document.attachEvent)
{
Core.addEventListener = function(target, type, listener)
{
// prevent adding the same listener twice, since DOM 2
// Events ignores duplicates like this
if (Core._findListener(target, type, listener) != -1)
return;
// listener2 calls listener as a method of target in one of
// two ways, depending on what this version of IE supports,
// and passes it the global event object as an argument
var listener2 = function()
{
var event = window.event;
if (Function.prototype.call)
{
listener.call(target, event);
}
else
{
target._currentListener = listener;
target._currentListener(event)
target._currentListener = null;
}
};
// add listener2 using IE's attachEvent method
target.attachEvent("on" + type, listener2);
// create an object describing this listener so we can
// clean it up later
var listenerRecord =
{
target: target,
type: type,
listener: listener,
listener2: listener2
};
// get a reference to the window object containing target
var targetDocument = target.document || target;
var targetWindow = targetDocument.parentWindow;
// create a unique ID for this listener
var listenerId = "1" + Core._listenerCounter++;
// store a record of this listener in the window object
if (!targetWindow._allListeners)
targetWindow._allListeners = {};
targetWindow._allListeners[listenerID] = listenerRecord;
// store this listener's ID in target
if (!target._listeners) target._listeners = [];
target._listeners[target._listeners.length] = listenerId;
// set up Core._removeAllListeners to clean up all
// listeners on unload
if (!targetWindow._unloadListenerAdded)
{
targetWindow._unloadListenerAdded = true;
targetWindow.attachEvent(
"onunload", Core._removeAllListeners);
}
};
Core.removeEventListener = function(target, type, listener)
{
// find out if the listener was actually added to target
var listenerIndex = Core._findListener(
target, type, listener);
if (listenerIndex == -1) return;
// get a reference to the window object containing target
var targetDocument = target.document || target;
var targetWindow = targetDocument.parentWindow;
// obtain the record of the listener from the window object
var listenerId = target._listeners[listenerIndex];
var listenerRecord =
targetWindow._allListeners[listenerId];
// remove the listener, and remove its ID from target
target.detachEvent("on" + type, listenerRecord.listener2);
target._listeners.splice(listenerIndex, 1);
// remove the record of the listener from the window object
delete targetWindow._allListeners[listenerId];
};
Core.preventDefault = function(event)
{
event.returnValue = false;
};
Core.stopPropagation = function(event)
{
event.cancelBubble = true;
};
Core._findListener = function(target, type, listener)
{
// get the array of listener IDs added to target
var listeners = target._listeners;
if (!listeners) return -1;
// get a reference to the window object containing target
var targetDocument = target.document || target;
var targetWindow = targetDocument.parentWindow;
// searching backward (to speed up onunload processing),
// find the listener
for (var i = listeners.length - 1; i >= 0; i--)
{
// get the listener's ID from target
var listenerId = listeners[i];
// get the record of the listener from the window object
var listenerRecord =
targetWindow._allListeners[listenerId];
// compare type and listener with the retrieved record
if (listenerRecord.type == type &&
listenerRecord.listener == listener)
{
return i;
}
}
return -1;
};
Core._removeAllListeners = function()
{
var targetWindow = this;
for (id in targetWindow._allListeners)
{
var listenerRecord = targetWindow._allListeners[id];
listenerRecord.target.detachEvent(
"on" + listenerRecord.type, listenerRecord.listener2);
delete targetWindow._allListeners[id];
}
};
Core._listenerCounter = 0;
}
Core.addClass = function(target, theClass)
{
if (!Core.hasClass(target, theClass))
{
if (target.className == " ")
{
target.className = theClass;
}
else
{
target.className += " " + theClass;
}
}
};
Core.getElementsByClass = function(theClass)
{
var elementArray = [];
if (typeof document.all != "undefined")
{
elementArray = document.all;
}
else
{
elementArray = document.getElementsByTagName("*");
}
var matchedArray = [];
var pattern = new RegExp("(^| )" + theClass + "( |$)");
for (var i = 0; i < elementArray.length; i++)
{
if (pattern.test(elementArray[i].className))
{
matchedArray[matchedArray.length] = elementArray[i];
}
}
return matchedArray;
};
Core.hasClass = function(target, theClass)
{
var pattern = new RegExp("(^| )" + theClass + "( |$)");
if (pattern.test(target.className))
{
return true;
}
return false;
};
Core.removeClass = function(target, theClass)
{
var pattern = new RegExp("(^| )" + theClass + "( |$)");
target.className = target.className.replace(pattern, "$1");
target.className = target.className.replace(/ $/, " ");
};
Core.getComputedStyle = function(element, styleProperty)
{
var computedStyle = null;
if (typeof element.currentStyle != "undefined")
{
computedStyle = element.currentStyle;
}
else
{
computedStyle =
document.defaultView.getComputedStyle(element, null);
}
return computedStyle[styleProperty];
};
Core.start = function(runnable)
{
Core.addEventListener(window, "load", runnable.init);
};
