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DHTML & ALPHABET SOUP

DHTML & ALPHABET SOUP. Sp.772 spring 2002. A combination. Html 4.0 Javascript The document object model (DOM) -- accessing individual document objects Cascading style sheets -- separation of form and content Netscape 6, IE 5.5/6. DOM.

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DHTML & ALPHABET SOUP

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  1. DHTML & ALPHABET SOUP Sp.772 spring 2002

  2. A combination • Html 4.0 • Javascript • The document object model (DOM) -- accessing individual document objects • Cascading style sheets -- separation of form and content • Netscape 6, IE 5.5/6

  3. DOM • Document.images[] accesses all the images in a document (we’ve seen it in billboard type image-displays) • Suppose we want to access headings, paragraphs, and individual words • <p id=“simple”>simple paragraph</p> • In javascript: var para = document.getElementByID(“simple”)

  4. getElementsby… • Var headings = document.getElementsByTagName(“h1”); • Var secondheading = headings[2]

  5. CSS • The element of style • Para.style.color = “#00FF00”; • Changes the paragraph to green • Other properties: style.font-size style.font-family style.background-color, style.background-image

  6. Rollover link color changes <style> a {text-decoration: none; color: #0000FF; } </style> <script language=“javascript”> Function turnOn(currentLink) { CurrentLink.style.color = “#990000”; CurrentLink.style.textDecoration = “underline”;}

  7. Continued… • Function turnOff(currentlink) { currentLink.style.color = “#0000FF”; currentLink.style.textDecoration = “none”;} </script> <head> <a href=“home.html” onMouseOver=“turnOn(this);” onMouseOut = “turnOff(this);”> home </a>

  8. ..explained • When the users’ mouse goes over a link the event handler passes it to turnOn, modifying the style of the current link • Note that values for style elements are specified as strings (e.g. “underline”)

  9. A dynamic CSS toolbar..hang on! • Highlights cells of a table • Html for a cell: • <td class = “toolbar” id = “news” width -= “120”> <a href=“#” onMouseOver=“linkOn(this, ‘news’);” • onMouseOut = “linkOff(this, ‘news’);”> News! </a> </td>

  10. linkOn • Function linkOn(currentLink, cell) { currentLink.style.color = “#990000”; currentLink.style.fontWeight = “bold”; currentLink.style.textDecoration = “underline”; Var CurrentCell = document.getElementById(cell); currentCell.style.backgroundColor=“#CCCCCC”; }

  11. linkOff • Function linkOn(currentLink, cell) { currentLink.style.color = “#FFFFFF”; currentLink.style.fontWeight = “normal”; currentLink.style.textDecoration = “none”; Var CurrentCell = document.getElementById(cell); currentCell.style.backgroundColor=“#666666”; }

  12. The header • <style type=“text/css”> a {font-family: Arial, Helvetica, sans-serif; font-size: 12px; color: #FFFFFF; text-decoration: none;} . toolbar { background-color: #666666;} </style>

  13. style classes • <style type=“text/css”> .welcome { font-family….} </style> …. <p class=“welcome”>Welcome to Bill’s World!</p>

  14. Layers • A positionable container (like photoshop) • x,y,z dimensions • z dimension points out at the user • <div id=“MyLayer” style = “position.absolute;z-index:1; left:100px;top:10px; width:300px;height:30px; background-color: #FFCC00;”>

  15. div attributes • position: can be absolute or relative (to any containing elemnt) • left: distance from left edge of document/containing element (eg 100px) • top: distance from top..(in pixels, too) • z-index: stacking order of display if layers are overlapping. higher numbers win. elements without a z-index lose

  16. Tabbed Folders (a la Hotmail) • visibility:visible • visibility:hidden • have some function keep track of the current tab and the moused-over newtab, change their visibilities appropriately

  17. Browser Detection • if (document.getElementById) {isDOM = true;} else if(parseInt(navigator.appVersion) >= 4) { if(navigator.appName == “Netscape”) {isNN4 = true;} else if (navigator.appName==“Microsoft Internet Explorer”) {isIE4= true;}

  18. Drop Down Menu Example • <td width=“100”> • <div id = “linksLayer” style=“position:absolute;left:211px….visibility:hidden;z-index:2”> • <a href=“#”>DHTML</a><br> • <a href=“#>CSS</a><br> </div> <a href=“#” onClick=showLayer(‘linksLayer’);” onDblClick=“hideLayer(‘linksLayer’);”>Links</a> </td>

  19. show/hideLayer • function showLayer(layerid) { • var layer=document.getElementByID(layerid); • layer.style.visibility = “visible”;} • function hideLayer(layerid) { • var layer=document.getElementByID(layerid); • layer.style.visibility = “hidden”;}

  20. more info • w3c.org/style • w3c.org/dom

  21. Exercise… • drop linkys • WEDNESDAY: SHIGERU MIYAGAWA • GUEST LECTURES!!!!!!!!!!! WILL BE FUN. • UROP OPPRTUNITIES ABOUND! • REMINDER: • May 15th FINAL PROJECTS DUE • AT LEAST ONE MEMBER FROM EACHGROUP MUST GO TO PRESENT THAT NIGHT. 7:30pm

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