Event Attributes Reference

In preparation for a more dynamic Web, the W3C has defined a set of core events that are associated with nearly every HTML or XHTML element. Most of these events cover simple user interaction, such as the click of a mouse button or a key being pressed. A few elements, such as form controls, have some special events associated with them. For example, form events might indicate that the field has received focus from the user or that the form was submitted. Intrinsic events, such as a document loading and unloading, are also defined. All the W3C-defined events are described in Table A-1.

This event model is far from complete, and it still is not fully supported by some browsers. The event model should be considered a work in progress. It will certainly change as the Document Object Model (DOM) is extended. More information about the DOM can be found at http://www.w3.org/DOM/. Already browser vendors are busy paving the way with their own events.

W3C-Defined Core Events

Table A-1

Event attribute	Description
onblur	Occurs when an element loses focus, meaning that the user has moved focus to another element, typically either by clicking the mouse or tabbing.
onchange	Signals that the form control has lost user focus and its value has been modified during its last access.
onclick	Indicates that the element has been clicked.
ondblclick	Indicates that the element has been double-clicked.
onfocus	Indicates that an element has received focus; namely, it has been selected for manipulation or data entry.
onkeydown	Indicates that a key is being pressed down with focus on the element.
onkeypress	Describes the event of a key being pressed and released with focus on the element.
onkeyup	Indicates that a key is being released with focus on the element.
onload	Indicates the event of a window or frame set finishing the loading of a document.
onmousedown	Indicates the press of a mouse button with focus on the element.
onmousemove	Indicates that the mouse has moved while over the element.
onmouseout	Indicates that the mouse has moved away from an element.
onmouseover	Indicates that the mouse has moved over an element.
onmouseup	Indicates the release of a mouse button with focus on the element.
onreset	Indicates that the form is being reset, possibly by the click of a reset button.
onselect	Indicates the selection of text by the user, typically by highlighting the desired text.
onsubmit	Indicates a form submission, generally by clicking a submit button.
onunload	Indicates that the browser is leaving the current document and unloading it from the window or frame.

Extended Events

Some browsers support events other than those defined in the HTML and XHTML specifications. Microsoft, in particular, has introduced a variety of events to capture more complex mouse actions such as dragging, element events such as the bouncing of marquee text, data-binding events signaling the loading of data into an object, and fine-grain event control to catch events just before or after they happen. The basic meaning of the various extended events is briefly summarized in Table A-2.

CAUTION With events documentation, errors might exist. The event model changes rapidly, and the browser vendors have not stopped innovating in this area. Events were tested by the author for accuracy, but for the most accurate, up-to-date event model for Internet Explorer, visit http://msdn.microsoft.com/.

Table A-2

Event attribute	Description
onabort	Triggered by the user aborting the image load with a stop button or similar effect.
onactivate	Fires when the object is set as the active element.
onafterprint	Fires after user prints a document or previews a document for printing.
onafterupdate	Fires after the transfer of data from the element to a data provider, namely a data update.
onbeforeactivate	Fires immediately before the object is set as the active element.
onbeforecopy	Fires just before selected content is copied and placed in the user's system clipboard.
onbeforecut	Fires just before selected content is cut from the document and added to the system clipboard.
onbeforedeactivate	Fires immediately before the active element is changed from one object to another.
onbeforeeditfocus	Fires before an object contained in an editable element is focused for editing.
onbeforepaste	Fires before the selected content is pasted into a document.
onbeforeprint	Fires before the user prints a document or previews a document for printing.
onbeforeunload	Fires just prior to a document being unloaded from a window.
onbeforeupdate	Triggered before the transfer of data from the element to the data provider. Might be triggered explicitly, or by a loss of focus or a page unload forcing a data update.
onbounce	Triggered when the bouncing contents of a marquee touch one side or another.
oncontextmenu	Triggered when the user right-clicks (invokes the context menu) on an element.
oncontrolselect	Fires when the user makes a control selection of the object.
oncopy	Fires on target when selected content is pasted into a document.
oncut	Fires when selected content is cut from a document and added to the system clipboard.
ondataavailable	Fires when data arrives from data sources that transmit information asynchronously.
ondatasetchanged	Triggered when the initial data is made available from a data source or when the data changes.
ondatasetcomplete	Indicates that all the data is available from the data source.
ondeactivate	Fires when the active element is changed to another object.
ondrag	Fires continuously during a drag operation.
ondragend	Fires when the user releases during a drag operation.
ondragenter	Fires when the user drags an object onto a valid drop target.
ondragleave	Fires when the user drags the object off a valid drop target.
ondragover	Fires continuously when the object is over a valid drop target.
ondragstart	Fires when the user begins to drag a highlighted selection.
ondrop	Fires when the mouse is released during a drag-and-drop operation.
onerror	Fires when the loading of a document, particularly the execution of a script, causes an error. Used to trap runtime errors.
onerrorupdate	Fires if a data transfer has been canceled by the onbeforeupdate event handler.
onfilterchange	Fires when a page filter changes state or finishes.
onfinish	Triggered when a looping marquee finishes.
onfocusin	Fires just before an object receives focus.
onfocusout	Fires when an object is losing focus.
onhelp	Triggered when the user presses the F1 key or similar help button in the user agent.
onlayoutcomplete	Fires when the print or print preview process finishes.
onlosecapture	Fires when the object loses mouse capture.
onmouseenter	Fires when the user moves the mouse pointer into the object.
onmouseleave	Fires when the user moves the mouse pointer away from the object.
onmousewheel	Fires when the mouse scroll wheel is used.
onmove	Triggered when the user moves a window.
onmoveend	Fires when an object stops moving.
onmovestart	Fires when an object starts moving.
onpaste	Fires when selected content is pasted into a document.
onpropertychange	Fires when a property changes on an object.
onreadystatechange	Similar to onload. Fires whenever the ready state for an object has changed.
onresize	Triggered whenever an object is resized.
onresizeend	Fires when the user finishes changing the dimensions of an object.
onresizestart	Fires when the user begins to change the dimensions of an object.
onrowenter	Indicates that a bound data row has changed and new data values are available.
onrowexit	Fires just prior to a bound data-source control changing the current row.
onrowsdelete	Fires when dataset rows are about to be deleted.
onrowsinserted	Fires when dataset rows are inserted.
onscroll	Fires when a scrolling element is repositioned.
onselectionchange	Fires when the selection state of a document changes.
onselectstart	Fires when the user begins to select information by highlighting.
onstart	Fires when a looped marquee begins or starts over.
onstop	Fires when the user clicks the stop button in the browser.
ontimeerror	Fires whenever a time-specific error occurs, usually as a result of setting a property to an invalid value.

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