event | NN 4 IE 4 DOM 2
The event object contains information about a user- or system-generated event. But there are three different kinds of event objects, one for each of the event object models deployed in browsers: IE for Windows, Navigator 4, and Netscape 6 (from the W3C DOM). IE 5 for Macintosh implements a hybrid of the IE for Windows and Netscape 6 version. See Chapter 6 for examples of processing events in a cross-browser environment. It is rare that an event object property applies to more than one of the event models, so pay special attention to the browser compatibility listings for each of the following properties.
The Netscape 6 event object is more complex in some ways due to the object-oriented nature of the underlying W3C DOM Event object structure. Rather than being an all-encompassing object (as the IE event object is), the Netscape 6 event object exposes different sets of properties and methods depending on the classification of event. All event classes share the properties and methods of the W3C DOM root Event object. But actual event object instances belong to one of the Event object's subclasses (and sometimes, sub-subclasses). These subclasses are known as UIEvent (so-called user interface events such as DOMFocusIn), MouseEvent (including the well-known mouse events), MutationEvent (events that signal a scripted change to the node structure of the document), and, coming in DOM Level 3, TextEvent (keyboard-related events). Netscape 6 implements its own, temporary keyboard events classification under the name KeyEvent, which is a subclass of UIEvent, although it borrows some MouseEvent properties for scripting convenience.
By and large, this functional division of objects won't impact your Netscape 6 event processing because an event listener function for a particular kind of event will be looking for properties associated with that event. The event class is of little concern. Still, it is instructive to see the way event object properties and methods cascade through this object-oriented structure. The following table illustrates the distribution of properties among Netscape 6 and W3C DOM event classes.
And the following table illustrates the distribution of methods among Netscape 6 and W3C DOM event classes.
The event object in Netscape 6 also implements the properties of the Navigator 4 static Event object, and it inherits an enormous list of W3C DOM TextEvent object constants that represent nonalphanumeric keyboard key codes (which have constant names like eventObject.DOM_VK_PAGE_UP). These keyboard constants are defined in the forthcoming W3C DOM Level 3 events module, but are already implemented in Netscape 6 (although the values don't exactly line up yet). A list of properties for the Navigator 4 static Event object appears in the Event object discussion following the current foray through an instance of an event.
As described in detail throughout Chapter 6, you must use different script techniques to obtain a reference to an event object in the IE and Navigator event models. Once you have that reference, you are well on your way to equalizing event processing across browsers. The example fragments that follow assume that previous script statements have obtained a reference to the browser-specific event object (usually shown in the example as stored in a variable called evt).
| Event | UIEvent | MouseEvent | KeyEventImplemented in Netscape 6 for additional functionality or in lieu of unfinished DOM Level 3 keyboard event model. Borrows some MouseEvent properties for scripting convenience. | TextEventProposed for DOM Level 3, but not implemented in Netscape 6. | MutationEvent
--- | --- | --- | --- | --- | --- | ---
Event properties
bubbles | √ | √ | √ | √ | √ | √
cancelable | √ | √ | √ | √ | √ | √
cancelBubble IE property implemented in Netscape 6 for cross-browser convenience. | √ | √ | √ | √ |  | √
currentTarget | √ | √ | √ | √ | √ | √
eventPhase | √ | √ | √ | √ | √ | √
originalTarget8 | √ | √ | √ | √ |  | √
target | √ | √ | √ | √ | √ | √
timeStamp | √ | √ | √ | √ | √ | √
type | √ | √ | √ | √ | √ | √
UIEvent properties
detail |  | √ | √ | √ | √ |
view |  | √ | √ | √ | √ |
MouseEvent properties
altKey |  |  | √ | √ |  |
button |  |  | √ |  |  |
clientX |  |  | √ | √ |  |
clientY |  |  | √ | √ |  |
ctrlKey |  |  | √ | √ |  |
metaKey |  |  | √ | √ |  |
relatedTarget |  |  | √ |  |  |
screenX |  |  | √ | √ |  |
screenY |  |  | √ | √ |  |
shiftKey |  |  | √ | √ |  |
KeyEvent properties
charCode8 |  |  |  | √ |  |
isChar8 |  |  |  | √ |  |
keyCode8 |  |  |  | √ |  |
rangeOffset8 |  |  |  | √ |  |
rangeParent8 |  |  |  | √ |  |
TextEvent properties |  |  |  |  |  |
keyVal9 |  |  |  |  | √ |
numPad9 |  |  |  |  | √ |
outputString9 |  |  |  |  | √ |
virtKeyVal9 |  |  |  |  | √ |
visibleOutputGenerated9 |  |  |  |  | √ |
MutationEvent properties
attrChange |  |  |  |  |  | √
attrName |  |  |  |  |  | √
newValue |  |  |  |  |  | √
prevValue |  |  |  |  |  | √
relatedNode |  |  |  |  |  | √
| Event | UIEvent | MouseEvent | KeyEventImplemented in Netscape 6 for additional functionality or in lieu of unfinished DOM Level 3 keyboard event model. Borrows some MouseEvent properties for scripting convenience. | TextEventProposed for DOM Level 3, but not implemented in Netscape 6. | MutationEvent
--- | --- | --- | --- | --- | --- | ---
Event methods
initEvent( ) | √ | √ | √ | √ | √ | √
getPreventDefault( )11 | √ | √ | √ | √ |  | √
preventDefault( ) | √ | √ | √ | √ | √ | √
stopPropagation( ) | √ | √ | √ | √ | √ | √
UIEvent methods
initUIEvent( ) |  | √ |  |  |  |
MouseEvent methods
initMouseEvent( ) |  |  | √ |  |  |
KeyEvent methods
initKeyEvent( ) |  |  |  | √ |  |
TextEvent methods
checkModifier( )12 |  |  |  |  | √ |
initModifier( )12 |  |  |  |  | √ |
initTextEvent( )12 |  |  |  |  | √ |
MutationEvent methods
initMutationEvent( ) |  |  |  |  |  | √
Object Model Reference
eventObj [window.]event
Object-Specific Properties
altKey | altLeft | attrChange | attrName
behaviorCookie | behaviorPart | bookmarks | boundElements
bubbles | button | cancelable | cancelBubble
charCode | clientX | clientY | contentOverflow
ctrlKey | ctrlLeft | currentTarget | data
dataFld | dataTransfer | detail | eventPhase
fromElement | isChar | keyCode | layerX
layerY | metaKey | modifiers | newValue
nextPage | offsetX | offsetY | originalTarget
pageX | pageY | prevValue | propertyName
qualifier | rangeOffset | rangeParent | reason
recordset | relatedNode | relatedTarget | repeat
returnValue | screenX | screenY | shiftKey
shiftLeft | srcElement | srcFilter | srcUrn
target | timeStamp | toElement | type
view | wheelDelta | which | x
y |  |  |
Object-Specific Methods
getPreventDefault( ) | initEvent( ) | initKeyEvent( ) | initMouseEvent( )
initMutationEvent( ) | initUIEvent( ) | preventDefault( ) | stopPropagation( )
Object-Specific Event Handler Properties
None.

altKey | NN 6 IE 4 DOM 2
| Read-only
Returns true if the left or right Alt key is down at the time the event fired.
Example
    if (evt.altKey) {
        //handle case of Alt key down
    }
Value
Boolean value: true | false.
Default
false

altLeft | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns true if the left Alt key is down at the time the event fired.
Example
    if (evt.altLeft) {
        //handle case of left Alt key down
    }
Value
Boolean value: true | false.
Default
false

attrChange | NN 6 IE n/a DOM 2
| Read-only
Returns an integer code corresponding to the type of change made to an Attr node as the result of a DOMAttrModified event type of W3C DOM mutation event. Every mutation event object has three constants that also correspond to the integer values, which you can use to make more verbose, but easier-to-read script comparisons for DOMAttrModified event processing. The values and constants are shown in the following table.
Value | Constant | Description
--- | --- | ---
1 | evtObj.MODIFICATION | Changed value of existing Attr node
2 | evtObj.ADDITION | The Attr node was added to the document tree
3 | evtObj.REMOVAL | The Attr node was removed from the document tree
Example
    if (evt.attrChange == evt.MODIFICATION) {
        // do post-processing of attribute value change
    }
Value
Integer value: 1 | 2 | 3.
Default
None.

attrName | NN 6 IE n/a DOM 2
| Read-only
Returns a string version of the name of an Attr node affected by a DOMAttrModified event type of W3C DOM mutation event.
Example
    var changedAttr = evt.attrName;
Value
String value.
Default
Empty string.

behaviorCookie, behaviorPart, bookmarks, boundElements | NN n/a IE 6(Win) DOM n/a
| Read-only
These properties are returned by the event object in IE 6 for Windows (with values 0, 0, null, and the empty array, respectively), but Microsoft does not document them. Perhaps they will be supported and implemented in a future version.

bubbles | NN 6 IE n/a DOM 2
| Read-only
Returns Boolean true if the default behavior of the event is to allow the event to bubble through the element hierarchy.
Example
    if (evt.bubbles) {
        // handle case of the event bubbling
    }
Value
Boolean value: true | false.
Default
Event type-specific.

button | NN 6 IE 4 DOM 2
| Read-only
Inidicates which mouse button was pressed to trigger the mouse event. Be aware that the typical Macintosh has only a one-button mouse. Also, if you want to intercept the right-click context menu in IE/Windows, use the oncontextmenu event handler.
A significant discrepancy exists among DOM specifications and implementations with respect to the numbers returned for this property. The W3C DOM, as implemented in Netscape 6, specifies a value of zero to indicate the left (primary) button. IE for Windows supports additional values for mouse button combinations.
Example
    if (evt.button == 2) {
        // handle event for right button
    }
Value
Integer value according to the following table.
Button(s) | IE | NN 6 | W3C DOM
No button | 0 | null | null
Left (primary) | 1 | 0 | 0
Middle | 4 | 1 | 1
Right | 2 | 2 | 2
Left + Right | 3 | n/a | n/a
Left + Middle | 5 | n/a | n/a
Right + Middle | 6 | n/a | n/a
Left + Middle + Right | 7 | n/a | n/a
Default
0

cancelable | NN 6 IE n/a DOM 2
| Read-only
Returns Boolean true if the event is of the type that can have its default behavior on the target element cancelled via the preventDefault( ) method.
Example
    if (evt.cancelable ) {
        evt.preventDefault( );
    }
Value
Boolean: true | false.
Default
Event type-specific.

cancelBubble | NN 6 IE 4 DOM n/a
| Read/Write
Specifies whether the event should propagate (bubble) up the element container hierarchy. You usually only need to set this property to true to override the default behavior and prevent the event from going any further. Netscape 6 implements this IE property for convenience. The W3C DOM equivalent is the stopPropagation( ) method of the event object.
Example
    evt.cancelBubble = true;
Value
Boolean: true | false.
Default
false

charCode | NN 6 IE n/a DOM n/a
| Read-only
Returns an integer corresponding to the Unicode value of the character generated by the key that fired the event. The character code is different from the key code, as the character code distinguishes between upper- and lowercase letters (for example, 97 for "a" and 65 for "A"), whereas the keyCode value is the same for that key, regardless of the character created from it. This property generally contains a value only for onkeypress events; the value is zero for onkeydown and onkeyup events. For the IE equivalent, see the keyCode property.
When the keyboard events module is completed for W3C DOM Level 3, this property will probably have a different name.
Example
    if (evt.charCode > 96 && evt.charCode < 123) {
        evt.target.value += String.fromCharCode(evt.charCode - 32);
        evt.preventDefault( );
    }
Value
Integer.
Default
Event-specific.

clientX, clientY | NN 6 IE 4 DOM 2
| Read-only
Indicate the horizontal (x) and vertical (y) coordinate of the mouse at the moment the current event fired. These coordinates are relative to the viewable document area of the browser window or frame. To convert these coordinates to the document's in IE, be sure to add the body element's scroll values (or html element's scroll values in IE 6 standards-compatible mode). For Netscape 6, the pageX and pageY properties provide coordinates in the document's space.
Example
    if ((evt.clientX >= 10 && evt.clientX <= 20) &&
    (evt.clientY >= 50 && evt.clientY <= 100)) {
        // process code for click in hot zone bounded by 10,50 and 20,100
    }
Value
Integer of pixel values.
Default
None.

contentOverflow | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns Boolean true if as-yet unrendered content requires a new layout rectangle to handle the overflow content. The property applies only to the onlayoutcomplete event if you deploy custom print or print preview templates. For more on the C++ programming required for such templates, visit http://msdn.microsoft.com/library/default.asp?url=/workshop/browser/hosting/printpreview/reference/reference.asp.
Value
Boolean: true | false.
Default
false

ctrlKey | NN 6 IE 4 DOM 2
| Read-only
Returns true if the left or right Control key was pressed at the instant the event fired. See Chapter 6 for testing for this key in cross-browser event handling code.
Example
    if (evt.ctrlKey) {
        // process for Control key being down
    }
Value
Boolean value: true | false.
Default
false

ctrlLeft | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns true if the left Control key was pressed at the instant the event fired.
Example
    if (evt.ctrlLeft) {
        // process for left Control key being down
    }
Value
Boolean value: true | false.
Default
false

currentTarget | NN 6 IE n/a DOM 2
| Read-only
Returns a reference to the node whose event listener is currently processing the event. Allows a function to know whether it is invoked from the actual target node or a different node during event propagation.
Example
    if (evt.currentTarget.nodeType == 1) {
        // process at element level for possible text node target
    }
Value
Reference to a node in event propagation hierarchy.
Default
Reference to event target.

data | NN |4| IE n/a DOM n/a
| Read-only
Provides accessory data associated with the Navigator 4-only dragdrop event. The data property returns the URL of the item being dropped onto the window or frame.
Example
    var srcDoc = evtObj.data;
Value
String.
Default
None.

dataFld | NN n/a IE 5(Win) DOM n/a
| Read/Write
Used with IE data binding, the dataFld property holds the name of the data source object's field associated with the column of the HTML table. This property contains a value after an oncellchange event in a table generated via data binding.
Value
String.
Default
Empty string.

dataTransfer | NN n/a IE 5(Win) DOM n/a
| Read-only
Returns a reference to the dataTransfer object to facilitate moving customized data between source and destination elements during a drag-and-drop operation. See the dataTransfer object for details of its usage.
Value
Reference to dataTransfer object.
Default
None.

detail | NN 6 IE n/a DOM 2
| Read-only
Returns an integer conveying event type-specific additional information. For mouse button events, the number indicates how many times the user clicked the mouse on the same coordinate position as the previous click without moving the cursor away from the location. Moving the cursor resets the counter to zero in preparation for the next press and release of the mouse button. For a DOMActivate event type, the detail property returns 1 for activation by a simple user action (click or tab), and 2 for a more complex action (a double-click).
Example
    if (evt.type == "click" && evt.detail > 5) {
        alert("Relax, dude!");
    }
Value
Integer.
Default
Event-type specific.

eventPhase | NN 6 IE n/a DOM 2
| Read-only
Returns an integer conveying whether the event listener is processing the event while in the capture phase, at the event target, or in the bubbling phase. W3C DOM event objects also implement plain-language constants corresponding to the three values.
Example
    if (evt.eventPhase == evt.AT_TARGET) {
        // process event listener from the event target
    }
Value
Integer value from the following table.
Value | Constant
1 | eventObjectReference.CAPTURING_PHASE
2 | eventObjectReference.AT_TARGET
3 | eventObjectReference.BUBBLING_PHASE
Default
2

fromElement | NN n/a IE 4 DOM n/a
| Read-only
Returns a reference to the object where the cursor was located just prior to the onMouseOver or onMouseOut event.
Example
    if (evt.fromElement.id == "lowerLevel") {
        ...
    }
Value
Element object reference.
Default
None.

isChar | NN 6 IE n/a DOM n/a
| Read-only
Returns true if the keyboard event is from a character key. In practice Netscape 6 returns true for all keys, including function keys. Use onkeydown or onkeyup event handlers to process noncharacter keys.
Value
Boolean value: true | false.
Default
true

keyCode | NN 6 IE 4 DOM n/a
| Read/Write
Slightly different characteristics for IE and Netscape 6, but the two browser classes treat the keyCode property the same way for onkeydown and onkeyup events. For these events, the keyCode property returns the code associated with the keyboard key, irrespective of the character that might be generated by that key. On a typical Latin character set keyboard, the A key generates the code 65. Modifier keys generate their own events and codes as they are pressed and released.
For the onkeypress event, only IE returns a significant value, corresponding to the Unicode value of the actual character displayed in a text box by typing the character (e.g., 65 for "A" and 97 for "a"). The equivalent property in Netscape 6 for the onkeypress event is charCode. See Chapter 6 about processing keyboard events.
Example
    if (evt.keyCode == 65) {
        ...
    }
Value
Integer.
Default
None.

layerX, layerY | NN 4 IE n/a DOM n/a
| Read-only
Provide the horizontal (x) and vertical (y) coordinate of the mouse at the moment the current event fired. These coordinates are relative to the containing layer. If no layers or positionable elements have been defined, the default layer of the base document is used as a reference point, thus equivalent to the pageX and pageY properties. In Netscape 6 and later, these properties are measured relative to the element's own rectangular space for text and password input elements, textarea elements, and select elements.
Example
    if ((evt.layerX >= 10 && evt.layerX <= 20) &&
    (evt.layerY >= 50 && evt.layerY <= 100)) {
        // process code for click in hot zone bounded by 10,50 and 20,100
    }
Value
Integer of pixel values.
Default
None

metaKey | NN 6 IE n/a DOM n/a
| Read-only
Returns true if the keyboard's Meta key (Command key on the Macintosh keyboard) was pressed at the instant the event fired.
Example
    if (evt.metaKey) {
        // process for meta key being down
    }
Value
Boolean value: true | false.
Default
false

modifiers | NN |4| IE n/a DOM n/a
| Read-only
Provides an integer that represents the keyboard modifier key(s) being held down at the time the Navigator 4-only event fired. You can use the & operator with a series of static Event object constants to find out whether a particular modifier key was pressed. See Chapter 6.
Example
    var altKeyPressed = evt.modifiers & Event.ALT_MASK;
Value
Integer.
Default
0

newValue, prevValue | NN 6 IE n/a DOM 2
| Read-only
Return a string with the new and previous values (respectively) of data associated with DOMAttrModified and DOMCharacterDataModified event types of the W3C DOM mutation events class. This information could be useful for creating an undo buffer for changes to an element's attribute or the content of a CharacterData node.
Example
    undoAttrBuffer = {attrNode:evt.relatedNode, oldVal:evt.prevValue};
Value
String value.
Default
Empty string.

nextPage | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns a string indicating whether the next page of a custom print template will appear on a left- or right-facing page. For more on the C++ programming required for templates, visit http://msdn.microsoft.com/library/default.asp?url=/workshop/browser/hosting/printpreview/reference/reference.asp.
Value
String constant: left | right | (empty string).
Default
Empty string.

offsetX, offsetY | NN n/a IE 4 DOM n/a
| Read-only
Provide the left and top coordinates of the mouse pointer relative to the containing element (exclusive of padding, borders, or margins) when the event fired. You can determine the containing element via the offsetParent property. See the Section 9.2 at the beginning of this chapter for information on offset measurement anomalies in Internet Explorer.
Example
    if (evt.offsetX <= 20 && evt.offsetY <=40) {
        ...
    }
Value
Integer pixel count.
Default
None.

originalTarget | NN 6 IE n/a DOM n/a
| Read-only
Returns a reference to a node that Netscape 6 internally treats as the genuine first target of the event. By and large, this information isn't helpful to DHTML scripting, because it dives into the internal construction of certain elements (e.g., an input element of type text has a div element nested inside of it, but the DOM node tree does not see the div element as a child node of the input element). For many events and event targets, the target and originalTarget properties reference the identical node.
Value
Node object reference
Default
Element-specific.

pageX, pageY | NN 4 IE n/a DOM n/a
| Read-only
Provide the left and top coordinates of the element's content relative to the top-left corner of the page area when the event fired. The measurements ignore any scrolling of the page.
Example
    if (evt.pageX <= 20 && evt.pageY <=40) {
        ...
    }
Value
Integer pixel count.
Default
None.

prevValue |
See newValue.

propertyName | NN n/a IE 5(Win) DOM n/a
| Read/Write
Returns a string containing the name of the object property that changed during an onpropertychange event. For other event types, the value is an empty string. If the changed property is a property of a property (e.g., a property of an element's style property), the returned value shows the "dot" version, such as style.color.
Example
    if (evt.propertyName.indexOf("style") == 0) {
        // perform further processing on a changed style
    }
Value
String property name.
Default
Empty string.

qualifier | NN n/a IE 5(Win) DOM n/a
| Read/Write
For use with IE data binding events (such as ondatasetcomplete). Returns a string value signifying a data source member, which may then be used as a parameter to access a data source's named recordset. Consult the Microsoft documentation for the Data Source Object you use to see if it provides qualifier data.
Value
String.
Default
Empty string.

rangeOffset | NN 6 IE n/a DOM n/a
| Read-only
Returns an integer of the character offset within a node that the Netscape 6 DOM considers a potential Range end point. The reference to the node is found in the associated rangeParent property of the event object. These two values can be passed as parameters to W3C DOM Range object methods for setting a start or end point. Thus, a mousedown event listener could establish the start point of a range, while a mouseup event listener function could set the end pointboth functions feeding rangeParent and rangeOffset values to the Range object methods.
Example
    var rng;
    function processMouseDown(evt) {
        rng = document.createRange( );
        rng.setStart(evt.rangeParent, evt.rangeOffset);
    }
Value
Integer.
Default
0

rangeParent | NN 6 IE n/a DOM n/a
| Read-only
Returns a reference to a document tree node that would be a suitable start or end point for a W3C text range. Use in concert with the rangeOffset property.
Example
    function processMouseUp(evt) {
        rng.setEnd(evt.rangeParent, evt.rangeOffset);
    }
Value
Reference to a node.
Default
None.

reason | NN n/a IE 4 DOM n/a
| Read/Write
Returns a code associated with an ondatasetcomplete event signifying whether the IE data binding data transfer was successful or, if incomplete, whether the transfer stopped due to an error or a stoppage by the client or user. This property must be examined in an event handler for the ondatasetcomplete event. In IE 4, the property is read-only. Although IE 5/Mac includes this property of the event object, it does not implement the associated event.
Example
    if (evt.reason == 2) {
        alert("An error occurred during the most recent update.");
    }
Value
One of three possible integer values:
0 Transfer was successful 1 Transfer aborted 2 An error halted the transfer
Default
None.

recordset | NN n/a IE 5(Win) DOM n/a
| Read/Write
Returns a reference to an IE data binding recordset object associated with a data-related event.
Value
Object reference.
Default
None.

relatedNode | NN 6 IE n/a DOM 2
| Read-only
Returns a reference to a node that is affected by the action that triggers some W3C DOM mutation events. This provides a more direct route to a node that is impacted by the event, according to the following table.
For other mutation event types, the property returns null; for other event classes, the property returns undefined.
Mutation event type | eventObj.relatedNode reference
--- | ---
DOMNodeInserted | Parent node of inserted node
DOMNodeRemoved | Original parent node of removed node
DOMAttrModified | Attr node
Example
    var newParent = evt.relatedNode;
Value
Reference to a node, null, or undefined.
Default
None.

relatedTarget | NN 6 IE n/a DOM 2
| Read-only
Returns a reference to a rendered node in the document tree that was the previous or next target for events, depending on the event type. For a mouseover event type, the relatedTarget property refers to the node from which the cursor arrived; for a mouseout event, the relatedTarget property refers to the node to which the cursor departed. The corresponding IE functionality is in the fromElement and toElement properties of the IE event object.
Example
    var beenThere = evt.relatedTarget;
Value
Reference to a node.
Default
None.

repeat | NN n/a IE 5(Win) DOM n/a
| Read/Write
For an onkeydown event only, returns Boolean true if the key has been down long enough to enter auto-repeat mode. You can prevent auto-repeated keys from being entered into a field with the following example.
Example
    function handleKeyDown( ) {
        if (evt.repeat) {
            evt.returnValue = false;
        }
    }
Value
Boolean value: true | false.
Default
false

returnValue | NN n/a IE 4 DOM n/a
| Read/Write
Provides the value to be returned to the event's source element to allow or prohibit the element's default action connected with the event. If you set event.returnValue to false, the element does not carry out its normal operation, such as navigating to a link or submitting the form. This property does not influence an actual value you may wish to return from an event handler function.
Example
    evt.returnValue = false;
Value
Boolean value: true | false.
Default
true

screenX, screenY | NN 4 IE 4 DOM 2
| Read-only
Provide the horizontal and vertical pixel coordinate points where the cursor was located on the video screen when the event occurred. The top-left corner of the screen is point 0,0. There is no particular coordination with the browser window or document, unless you have positioned the window and know where the active window area is in relation to the screen.
Example
    if (evt.screenX < 5 || evt.screenY < 5) {
        alert("You\'re too close to the edge!");
    }
Value
Any positive integer or zero.
Default
0

shiftKey | NN 6 IE 4 DOM 2
| Read-only
Returns true if the left or right Shift key was pressed at the instant the event fired.
Example
    if (evt.shiftKey) {
        // process for Shift key being down
    }
Value
Boolean value: true | false.
Default
false

shiftLeft | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns true if the left Shift key was pressed at the instant the event fired.
Example
    if (evt.shiftLeft) {
        // process for left Shift key being down
    }
Value
Boolean value: true | false.
Default
false

srcElement | NN n/a IE 4 DOM n/a
| Read-only
Refers to the element object that initially received the current event. This property is convenient in switch constructions for an event handler function that handles the same event type for a number of different elements. The corresponding property for Netscape 6 is target.
Example
    switch (evt.srcElement.id) {
        case "myDIV":
            ...
        ...
    }
Value
Element object reference.
Default
None.

srcFilter | NN n/a IE 4(Win) DOM n/a
| Read-only
Refers to the filter object that fired an onfilterchange event.
Value
Filter object reference.
Default
None.

srcUrn | NN n/a IE 5(Win) DOM n/a
| Read-only
String of the URN of an attached behavior that fired an event.
Value
String.
Default
null

target | NN 4 IE n/a DOM 2
| Read-only
Refers to the node object that is the intended destination of the current event. Unlike the corresponding IE srcElement property, the target property in Netscape 6 can refer to a text node, even if the event handler is defined for the element that surrounds the text node. Your event processing for such a scenario must take the nodeType into account to equalize the reference to the surrounding element for both IE and Navigator. See Chapter 6 for examples of cross-browser event handling code.
Example
    var elem = (evt.target) ? evt.target : evt.srcElement;
Value
Node object reference.
Default
None.

timeStamp | NN 6 IE n/a DOM 2
| Read-only
Provides an integer signifying a milliseconds value you can use as a relative indicator of when an event occurred. Although the W3C DOM suggests the value should be the time since 1 January 1970 (the Java and JavaScript epoch), you cannot rely on that value. But you can compare the timeStamp property value for two events to derive the elapsed time between events.
Example
    var clickTime = evt.timeStamp;
Value
Integer.
Default
Current timestamp.

toElement | NN n/a IE 4 DOM n/a
| Read-only
Returns a reference to the element object to which the cursor has moved that triggered the onmouseout event.
Example
    if (evt.toElement.id == "upperLevel") {
        ...
    }
Value
Element object reference.
Default
None.

type | NN 4 IE 4 DOM 2
| Read-only
Indicates the type of the current event (without the "on" prefix). Values are all lowercase.
Example
    if (evt.type == "change") {
        ...
    }
Value
Any event name (without the "on" prefix) as a string.
Default
None.

view | NN 6 IE n/a DOM 2
| Read-only
Returns a reference to the W3C DOM view (i.e., the window or frame object in Netscape's implementation) in which the event occurred.
Example
    var whichWin = evt.view;
Value
Reference to a window type of object.
Default
Current window.

wheelDelta | NN n/a IE 5.5(Win) DOM n/a
| Read-only
Returns an integer indicating which direction the user rolled the mouse wheel (for a mouse equipped with a wheel) during an onmousewheel event. A positive value means the user rolled the wheel toward the screen; a negative value means the opposite direction.
Example
    if (evt.wheelDelta > 0) {
        ...
    }
Value
Integer, typically 120 or -120.
Default
None.

which | NN 4 IE n/a DOM n/a
| Read-only
Returns a value relevant to the type of event. For mouse events, the property value is an integer indicating which mouse button was used (1 is the left button; 3 is the right button). For keyboard events, the property value is an integer of the keyboard character ASCII code. This property survives in Netscape 6 as a carryover from the Navigator 4 event model. Use the button, charCode, and keyCode properties if you no longer need to support Navigator 4.
Example
    if (evt.which == 65) {
        ...
    }
Value
Integer.
Default
None.

x, y | NN n/a IE 4 DOM n/a
| Read-only
Return the horizontal and vertical pixel coordinates of the mouse pointer at the time the event occurred. For all but relative-positioned elements, the coordinate system is the body element (or html element in IE 6 standards-compatible mode). If the event occurs inside a relative-positioned element's rectangle, the coordinate system is limited to that element's space (the element's top left corner being 0,0). A value of -1 is returned if the pointer was outside of the document area of the browser window.
Example
    if (evt.x < 20 && evt.y < 30) {
        ...
    }
Value
Integer.
Default
None.

getPreventDefault( ) | NN 6 IE n/a DOM n/a
Returns Boolean true if the preventDefault( ) method has been invoked for the current event object. Essentially lets a script inquire about the prevent-default state. This property is a Netscape 6 extension to the W3C DOM events module.
Parameters
None.
Returned Value
Boolean value: true | false.

initEvent( ) | NN 6 IE n/a DOM 2
initEvent("eventType", bubblesFlag, cancelableFlag) |
Indicates the minimum initialization required on an event object that is generated by document.createEvent( ). After a script-generated event is initialized, it may be used as a parameter to a node's dispatchEvent( ) method.
Parameters
String identifier for the event's type, such as click, mousedown, keypress, DOMAttrModified, and so on. Boolean value (true | false) determining whether the event's default propagation behavior is to bubble. Boolean value (true | false) determining whether the event's default action may be prevented via the preventDefault( ) method.
Returned Value
None.

initKeyEvent( ) | NN 6 IE n/a DOM n/a
initKeyEvent("eventType", bubblesFlag, cancelableFlag, view, ctrlKeyFlag, altKeyFlag, shiftKeyFlag, metaKeyFlag, keyCode, charCode) |
Initializes a newly created event object with a complete set of property values associated with any keyboard event. This method's name and parameter makeup may change for the formal DOM Level 3 events module, where keyboard events (tentatively called text events) will be published. All parameters must be present, and must be set to default values (such as false for Boolean key flags or zero for integer code numbers) if the values are not significant for the event type.
Parameters
String identifier for the event's type: keydown, keypress, keyup. Boolean value (true | false) determining whether the event's default propagation behavior is to bubble. Boolean value (true | false) determining whether the event's default action may be prevented via the preventDefault( ) method. Reference to the window or frame object in which the dynamically-generated event is supposed to have occurred. Boolean value (true | false) of the Control key state for this event. Boolean value (true | false) of the Alt key state for this event. Boolean value (true | false) of the Shift key state for this event. Boolean value (true | false) of the Meta key(e.g., Macintosh Command key) state for this event. Integer key code for this event. Integer character code for this event.
Returned Value
None.

initMouseEvent( ) | NN 6 IE n/a DOM 2
initMouseEvent("eventType", bubblesFlag, cancelableFlag, view, detailVal, screenX, screenY, clientX, clientY, ctrlKeyFlag, altKeyFlag, shiftKeyFlag, metaKeyFlag, buttonCode, relatedTargetNodeRef) |
Initializes a newly created event object with a complete set of property values associated with any mouse event. All parameters must be present, and must be set to default values (such as false for Boolean key flags, zero for integer values, or null for a node reference) if the values are not significant for the event type.
Parameters
String identifier for the event's type, such as click, mousedown, mousemove, mouseout, mouseover, mouseup. Boolean value (true | false) that determines whether the event's default propagation behavior is to bubble. Boolean value (true | false) that determines whether the event's default action may be prevented via the preventDefault( ) method. Reference to the window or frame object in which the dynamically-generated event is supposed to have occurred. Integer code for detail data associated with the event. Integer for horizontal screen coordinate. Integer for vertical screen coordinate. Integer for horizontal browser window coordinate. Integer for vertical browser window coordinate. Boolean value (true | false) of the Control key state for this event. Boolean value (true | false) of the Alt key state for this event. Boolean value (true | false) of the Shift key state for this event. Boolean value (true | false) of the Meta key(e.g., Macintosh Command key) state for this event. Integer button code for this event. Reference to node receiving the previous or next mouse event.
Returned Value
None.

initMutationEvent( ) | NN 6 IE n/a DOM 2
initMutationEvent("eventType", bubblesFlag, cancelableFlag, relatedNodeRef, prevValue, newValue, attrName, attrChangeCode) |
Initializes a newly created event object with a complete set of property values associated with any mutation event. All parameters must be present, and must be set to default values (such as false for Boolean key flags or zero for integer code numbers) if the values are not significant for the event type.
Parameters
String identifier for the event's type: DOMAttrModified, DOMCharacterDataModified, DOMNodeInserted, DOMNodeInsertedIntoDocument, DOMNodeRemoved, DOMNodeRemovedFrom-Document, DOMSubtreeModified. Boolean value (true | false) determining whether the event's default propagation behavior is to bubble. Boolean value (true | false) determining whether the event's default action may be prevented via the preventDefault( ) method. Reference to a node associated with the event. Applicable only to DOMNodeInserted, DOMNodeRemoved, DOMAttrModified event types. String of previous value for an Attr or CharacterData node. Applicable only to DOMAttrModified and DOMCharacterDataModified event types. String of new value for an Attr or CharacterData node. Applicable only to DOMAttrModified and DOMCharacterDataModified event types. String of the name of an Attr node. Applicable only to the DOMAttrModified event type. Integer for the code corresponding to the type of change the event simulates. Applicable only to the DOMAttrModified event type.
Returned Value
None.

initUIEvent( ) | NN 6 IE n/a DOM 2
initUIEvent("eventType", bubblesFlag, cancelableFlag, view, detailVal) |
Initializes a newly created event object with a complete set of property values associated with any UI event. All parameters must be present, and must be set to default values (such as false for Boolean key flags or zero for integer values) if the values are not significant for the event type.
Parameters
String identifier for the event's type, such as DOMFocusIn, DOMFocusOut, DOMActivate. Boolean value (true | false) determining whether the event's default propagation behavior is to bubble. Boolean value (true | false) determining whether the event's default action may be prevented via the preventDefault( ) method. Reference to the window or frame object in which the dynamically generated event is supposed to have occurred. Integer code for detail data associated with the event.
Returned Value
None.

preventDefault( ) | NN 6 IE n/a DOM 2
Instructs the current event to bypass the normal operation it performs on the node. Once set, the mode cannot be undone for the current event. The following Netscape 6 event listener function for an keypress event allows only numbers to be entered into a text field:
    function numsOnly(evt) {
        if (evt.charCode< 48 || evt.charCode > 57) {
            evt.preventDefault( );
        }
    }
This method is the equivalent of assigning false to the IE event.returnValue property, or having an event handler evaluate to return false.
Parameters
None.
Returned Value
None.

stopPropagation( ) | NN 6 IE n/a DOM 2
Prevents the current event from propagating through the capture or bubbling hierarchy beyond the node currently processing the event. This method performs the same action as assigning false to the event object's cancelBubble property (for bubbling propagation only).
Parameters
None.
Returned Value
None.