Creating an Animated Web Page Working with Objects Creating an Animated Web Page Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Objectives Define DHTML and describe its uses Understand objects, properties, methods, and the document object model Distinguish between different object models Work with object references and object collections Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Objectives Modify an object’s properties Apply a method to an object Create a cross-browser Web site using object detection Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Objectives Work with the style object to change the styles associated with an object Write functions to apply positioning styles to an object Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Objectives Insert event handlers to run a script in response to an event Place a JavaScript command in a link Run timed-delay and timed-interval commands Work with the properties of the display window Describe the techniques of linear and path animation Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Introduction to DHTML Developers began to look for ways to create dynamic pages New approach, in which the HTML code itself supported dynamic elements Known collectively as dynamic HTML, or DHTML Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Introduction to DHTML Interaction of three aspects A page’s HTML/XHTML code A style sheet that defines the styles used in the page A script to control the behavior of elements on the page Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Introduction to DHTML Some uses Animated text Pop-up menus Rollovers Web pages that retrieve their content from external data sources Elements that can be dragged and dropped Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Understanding JavaScript Objects JavaScript is an object-based language An object is any item associated with a Web page or Web browser Each object has Properties Methods Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model The organized structure of objects and events is called the document object model, or DOM Every object related to documents or to browsers should be part of the document object model In practice, browsers differ in the objects that their document object models support Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model Development of a Common DOM Basic model, or DOM Level 0 Supported browser window, Web document, and the browser itself Development followed two paths: one adopted by Netscape and the other adopted by Internet Explorer Internet Explorer DOM also provided for capturing events Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model Development of a Common DOM World Wide Web Consortium (W3C) stepped in to develop specifications for a common document object model DOM Level 1 DOM Level 2 DOM Level 3 Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model Development of a Common DOM Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model Development of a Common DOM Within each DOM, particular features may not be supported by every browser Code should be compatible with Netscape 4 Internet Explorer 5 W3C DOM Level 1 and 2 Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Exploring the Document Object Model The document tree Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects A DOM can be used by any scripting language including JavaScript and Java Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Object Names Each object is identified by an object name Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Object Names General form is object1.object2.object3… To reference the history you would use the form window.history For the body, you would use document.body Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Working with Object Collections Objects are organized into arrays called object collections document.collection Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Working with Object Collections Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Using document.all and document.getElementById Not all elements are associated with an object collection Can reference these objects using their id values document.all[“id”] document.all.id document.getElementById(“id”) Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Referencing Objects Referencing Tags Internet Explorer DOM document.all.tags(tag) W3C DOMs document.getElementsbyTagName(“tag”) document.getElementsbyTagName(“p”)[0] Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Object Properties The syntax for setting the value of an object property is object.property = expression Example document.title = “Avalon Books” Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Object Properties Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Object Properties Some properties are read-only Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Object Properties Storing a Property in a Variable variable = object.property Using Properties in a Conditional Expressions if(document.bgColor==“black”) { document.fgColor=“white” } else { document.fgColor=“black” } Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Object Methods object.method(parameters) Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site You can create this kind of code, known as cross-browser code, using two different approaches: browser detection or object detection Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Using Browser Detection Using browser detection, your code determines which browser (and browser version) a user is running navigator.appName Most browser detection scripts – commonly known as browser sniffers – use this property to extract information about the version number navigator.uerAgent Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Using Object Detection With object detection, you determine which document object model a browser supports var NS4DOM = document.layers ? true:false; var IEDOM = document.all ? true:false; var W3CDOM = document.getElementByID ? true:false; Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Employing Cross-Browser Strategies One strategy, called page branching, creates separate pages for each browser along with an initial page A script determines the capabilities of the user’s browser and automatically loads the appropriate page Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Employing Cross-Browser Strategies Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Employing Cross-Browser Strategies To automatically load a page into a browser based on the type of the browser detected, use the command location.href = url; A second cross-browser strategy is to use internal branching Most web developers apply a third cross-browser strategy Application programming interface or API Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating a Cross-Browser Web Site Employing Cross-Browser Strategies Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with the style Object The syntax for applying a style is object.style.attribute = value Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with the Style Object Setting an Element’s Position Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with the style Object Positioning Properties in the IE DOM Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Creating the Positioning Functions for Avalon Books Example function xCoord(id) { object=document.getElementByID(id); xc=parseInt(object.style.left); return xc; } Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Event Handlers An event handler is an attribute added to an element that specifies a program to be run in response to an event Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Event Handlers Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Event Handlers Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Working with Event Handlers Running JavaScript Commands as Links <a href=“javascript.script”>content</a> Using the onLoad Event Handler Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Animating an Object Working with Time-Delayed Commands setTimeout(“command”, delay); timeID = setTimeout(“command”, delay); clearTimeout(timeID); clearTimeout(); Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Animating an Object Running Commands at Specified Intervals timeID=setInterval(“command”,interval); setInterval(“command”, interval); clearInterval(timeID); clearInterval(); Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Animating an Object Animating the Avalon Books Web page Example Function moveAvalon() { var y=yCoord(“avalon”); if (y <= 260) { shiftIt(“avalon”, 0, 10); shiftIt(“books”, 0, 10); setTimeout(“moveAvalon()”, 30); } else { // run moveBooks function; } Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Controlling Layout for Different Monitor Resolutions Calculating the Size of the Display Window window.outerWidth window.outerHeight window.innerWidth window.innerHeight document.body.clientWidth document.body.clientHeight Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Controlling Layout for Different Monitor Resolutions Calculating the Size of the Display Window document.documentElement.offsetWidth document.documentElement.offsetHeight Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Using Path Animation Linear animation means that the animation takes place over a straight line Path animation means each set of coordinates in the path is entered into an array, and the animation moves point to point Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

New Perspectives on HTML, XHTML, and DHTML, Comprehensive Using Path Animation Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive

Tips for working with JavaScript Objects and DHTML If your code reuses the same object reference, store the object in a variable Place your customized functions in external files Use object detection Use path animation and create interesting visual effects Break up your animated effects into separate functions Tutorial 11 New Perspectives on HTML, XHTML, and DHTML, Comprehensive