mytitle = documenttitle in Java

Generator Code 3/9 in Java mytitle = documenttitle

To call the clear method of the document, you write this:

documentclear()

Events are actions that either the browser executes or the user performs while visiting your page Loading a Web page, moving the mouse over an image, closing a window, and submitting a form are all examples of events JavaScript deals with events by using commands called event handlers Any action by the user on the page triggers an event handler in your script Table 13-6 is a list of JavaScript s event handlers

Table 13-6

onabort onblur onchange onclick ondblclick onerror onfocus onkeydown onkeypress onkeyup onload onmousedown onmousemove onmouseout onmouseover

Description User cancels a page load An element loses focus because the user focuses on a different element User changes the contents of a form element or selects a different check box, radio button, or menu item User clicks an element with the mouse User double-clicks an element with the mouse Browser encounters an error in the scripts or other instructions on the page An element becomes the focus of the user s attention, like a form field when you start typing in it User presses and holds a key on the keyboard User presses and immediately releases a key on the keyboard User releases a depressed key Browser loads an HTML page User moves the mouse pointer over an element, presses the mouse button down, and holds it down User moves the mouse pointer anywhere on the page User moves the mouse pointer off an element User moves the mouse pointer over an element

(continued)

Part IV: Integrating Scripts with HTML Table 13-6 (continued)

Description User releases a held mouse button User clicks a form s Reset button User resizes the browser window User selects a check box, radio button, or menu item from a form User clicks a form s Submit button Browser stops displaying one Web page because it s about to load another

Not all objects support every event handler For example, the onload handler is supported by only the window and image objects The onsubmit event handler is supported by only the form object A common way to deal with event handlers is to use them as an attribute of an HTML element This is called an inline event handler Here is an example of the onsubmit inline event handler being used as an attribute of a <form> tag:

This example calls the submitIt function when the user clicks the form s Submit button You can also embed JavaScript commands in the HTML, like this:

A third way to use event handlers is to express them in JavaScript code, like this:

documentbutton1onclick = function () { alert( That tickles! )}

Document Object Model (DOM)

JavaScript gives you the tools to manipulate the objects in a Web page The Document Object Model (DOM) is the specification for how all those objects

are represented The DOM is a Web standard, defined by the World Wide Web Consortium (W3C; more information than you can imagine about the DOM specification is available at wwww3org/DOM) The DOM allows JavaScript to programmatically access and manipulate the contents of a document The DOM defines Each object on a Web page Attributes associated with those objects Methods that you can use to manipulate those objects By using the DOM, JavaScript can dynamically update the content, structure, and style of Web pages This means that you can use JavaScript to produce effects in your Web pages, such as Rewriting your document on the fly Changing styles and style sheets Page layout

Table 13-7 lists other script- and forms-related (X)HTML markup attributes that you might find in HTML files

Table 13-7