This text rewritten into the status line is difficult or impossible to detect with a screen reader. 

Although rewriting the status line did not interfere with the accessibility or inaccessibility of the 

JavaScript URL, web developers should ensure that all important information conveyed in the 

status line also be provided through the "alt" attribute, as described above. 

JavaScript uses so called "event handlers" as a trigger for certain actions or functions to occur. 

For instance, a web developer may embed a JavaScript function in a web page that 

automatically checks the content of a form for completeness or accuracy. An event handler 

associated with a "submit" button can be used to trigger the function before the form is actually 

submitted to the server for processing. The advantage for the government agency is that it 

saves government resources by not requiring the government s server to do the initial checking. 

The advantage for the computer user is that feedback about errors is almost instantaneous 

because the user is told about the error before the information is even submitted over the 

Internet. 

Web developers must exercise some caution when deciding which event handlers to use in their 

web pages, because different screen readers provide different degrees of support for different 

event handlers. The following table includes recommendations for using many of the more 

popular event handlers: 

onClick   The onClick event handler is triggered when the user clicks once on a 

particular item. It is commonly used on links and button elements and, used in 

connection with these elements, it works well with screen readers. If clicking on the 

element associated with the onClick event handler triggers a function or performs some 

other action, developers should ensure that the context makes that fact clear to all users. 

Do not use the onClick event handlers for form elements that include several options 

(e.g. select lists, radio buttons, checkboxes) unless absolutely necessary.  

onDblClick   The onDblClick event handler is set off when the user clicks twice rapidly 

on the same element. In addition to the accessibility problems it creates, it is very 

confusing to users and should be avoided.  

onMouseDown and onMouseUp   The onMouseDown and onMouseUp event handlers 

each handle the two halves of clicking a mouse while over an element   the process of 

(a) clicking down on the mouse button and (b) then releasing the mouse button. Like 

onDblClick, this tag should be used sparingly, if at all, by web developers because it is 

quite confusing. In most cases, developers should opt for the onClick event handler 

instead of onMouseDown.  

onMouseOver and onMouseOut   These two event handlers are very popular on many 

web sites. For instance, so called rollover gif s, which swap images on a web page when 

the mouse passes over an image, typically use both of these event handlers. These 

event handlers neither can be accessed by the mouse nor interfere with accessibility   a 

screen reader simply bypasses them entirely. Accordingly, web designers who use these 

event handlers should be careful to duplicate the information (if any) provided by these 

event handlers through other means.  

onLoad and onUnload   Both of these event handlers are used frequently to perform 

certain functions when a web page has either completed loading or when it unloads. 

National GACC Website and GACC Website Template  

36

  Implementation Guidelines