Fundamental JavaScript [In Control 2009]

FUNDAMENTAL JAVASCRIPT Aaron Gustafson

DOM SCRIPTING (a.k.a. Document Manipulation via JavaScript)

FUNDAMENTAL JAVASCRIPT DHTML ๏ …was all about animation and interactivity ๏ ...was invented by marketing wonks ๏ ...is really three technologies: JavaScript, CSS & HTML ๏ ...carried a lot of baggage: browser-speciﬁc, forked code, screen only & non-standard markup ๏ ...was a maintenance nightmare IN CONTROL 2009 3

FUNDAMENTAL JAVASCRIPT DOM Scripting ๏ …is the web standards approach to manipulating documents ๏ ...only requires a scripting language and valid markup ๏ ...is browser independent ๏ ...makes use of progressive enhancement ๏ ...just makes sense IN CONTROL 2009 4

FUNDAMENTAL JAVASCRIPT The document <!DOCTYPE html PUBLIC quot;-//W3C//DTD XHTML 1.0 Strict//ENquot; quot;http://www.w3.org/TR/XHTML1/DTD/XHTML1-strict.dtdquot;> <html xmlns=quot;http://www.w3.org/1999/XHTMLquot; xml:lang=quot;enquot; lang=quot;enquot;> <head> <title>Page Title</title> <meta http-equiv=quot;content-typequot; content=quot;text/html; charset=utf-8quot; /> <meta http-equiv=quot;Content-Languagequot; content=quot;en-usquot; /> </head> <body> <h1>This is a heading</h1> <p>This is a paragraph with a <a href=quot;http://easy-reader.netquot;>link</a></p> <ul> <li>a list item</li> <li>another list item</li> <li>a third list item</li> </ul> </body> </html> IN CONTROL 2009 5

FUNDAMENTAL JAVASCRIPT The DOM html IN CONTROL 2009 6

FUNDAMENTAL JAVASCRIPT The DOM html head body title meta meta h1 p ul a li li li IN CONTROL 2009 6

FUNDAMENTAL JAVASCRIPT The DOM p this is a paragraph a . of text with a href=quot;http://easy-reader.netquot; link IN CONTROL 2009 6

FUNDAMENTAL JAVASCRIPT CSS getter { setter } IN CONTROL 2009 7

FUNDAMENTAL JAVASCRIPT CSS p { color: red; } IN CONTROL 2009 7

FUNDAMENTAL JAVASCRIPT CSS #footer { font-size: small; } IN CONTROL 2009 7

FUNDAMENTAL JAVASCRIPT DOM Scripting IN CONTROL 2009 8

FUNDAMENTAL JAVASCRIPT DOM Scripting var myNode = document.getter(); IN CONTROL 2009 8

FUNDAMENTAL JAVASCRIPT DOM Scripting myNode.setter(); IN CONTROL 2009 8

FUNDAMENTAL JAVASCRIPT Getters ๏ document.getElementById( ID ); ๏ document.getElementsByTagName( tagName ); ๏ element.getAttribute( attributeName ); IN CONTROL 2009 9

FUNDAMENTAL JAVASCRIPT Using getters ๏ var content = document.getElementById( 'content' ); ๏ var abbrs = document.getElementsByTagName( 'abbr' ); ๏ var title = abbrs[0].getAttribute( 'title' ); IN CONTROL 2009 10

FUNDAMENTAL JAVASCRIPT Language comparison ๏ English Get the element with the ID “content”. ๏ CSS #content { } ๏ DOM document.getElementById( 'content' ) IN CONTROL 2009 11

FUNDAMENTAL JAVASCRIPT Language comparison ๏ English Get all the paragraphs in a document. ๏ CSS p { } ๏ DOM document.getElementsByTagName( 'p' ); IN CONTROL 2009 12

FUNDAMENTAL JAVASCRIPT Language comparison ๏ English Get all the paragraphs within the element with the ID “content”. ๏ CSS #content p { } ๏ DOM document.getElementById( 'content' ) .getElementsByTagName( 'p' ); IN CONTROL 2009 13

FUNDAMENTAL JAVASCRIPT Content generation ๏ Bad: ‣ document.write(); ‣ innerHTML IN CONTROL 2009 14

FUNDAMENTAL JAVASCRIPT Content generation ๏ Good: ‣ document.createElement( tagName ); ‣ document.createTextNode( text ); ‣ element.setAttribute( name, value ); IN CONTROL 2009 15

FUNDAMENTAL JAVASCRIPT Generation in action ๏ var abbr = document.createElement( 'abbr' ); ๏ var text = document.createTextNode( 'TN' ); ๏ abbr.setAttribute( 'title', 'Tennessee' ); IN CONTROL 2009 16

FUNDAMENTAL JAVASCRIPT Adding to the DOM ๏ element.appendChild( newNode ); ๏ element.insertBefore( newNode, targetNode ); IN CONTROL 2009 17

FUNDAMENTAL JAVASCRIPT Adding to the DOM var abbr = document.createElement( 'abbr' ); var text = document.createTextNode( 'TN' ); abbr.setAttribute( 'title', 'Tennessee' ); abbr.appendChild( text ); var p = document.getElementsByTagName( 'p' )[0]; p.appendChild( abbr ); IN CONTROL 2009 18

TIME FOR AN EXAMPLE

FUNDAMENTAL JAVASCRIPT The idea Make use of the cite attribute in blockquotes. IN CONTROL 2009 20

FUNDAMENTAL JAVASCRIPT The document <!DOCTYPE html PUBLIC quot;-//W3C//DTD XHTML 1.0 Strict//ENquot; quot;http://www.w3.org/TR/XHTML1/DTD/XHTML1-strict.dtdquot;> <html xmlns=quot;http://www.w3.org/1999/XHTMLquot; xml:lang=quot;enquot; lang=quot;enquot;> <head> <title>Example 1</title> <meta http-equiv=quot;content-typequot; content=quot;text/html; charset=utf-8quot; /> <meta http-equiv=quot;Content-Languagequot; content=quot;en-usquot; /> </head> <body> <blockquote cite=quot;http://en.wikipedia.org/wiki/Progressive_Enhancementquot;> <p>Progressive Enhancement, as a label for a strategy for Web design, was coined by Steven Champeon in a series of articles and presentations for Webmonkey and the SxSW Interactive conference.</p> </blockquote> </body> </html> IN CONTROL 2009 21

FUNDAMENTAL JAVASCRIPT The page Progressive Enhancement, as a label for a strategy for Web design, was coined by Steven Champeon in a series of articles and presentations for Webmonkey and the SxSW Interactive conference. IN CONTROL 2009 22

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document 2. Get the value of the cite attribute 3. Create a new anchor element node 4. Set the href attribute of the anchor 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 24

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document 2. Get the value of the cite attribute 3. Create a new anchor element node 4. Set the href attribute of the anchor 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute 3. Create a new anchor element node 4. Set the href attribute of the anchor 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node 4. Set the href attribute of the anchor 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node createElement 4. Set the href attribute of the anchor 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node createElement 4. Set the href attribute of the anchor setAttribute 5. Create a new text node with the word “source” 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node createElement 4. Set the href attribute of the anchor setAttribute 5. Create a new text node with the word “source” createTextNode 6. Insert the text into the anchor 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node createElement 4. Set the href attribute of the anchor setAttribute 5. Create a new text node with the word “source” createTextNode 6. Insert the text into the anchor appendChild 7. Insert the anchor into the blockquote. IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The idea 1. Find all the blockquotes in a document getElementsByTagName 2. Get the value of the cite attribute getAttribute 3. Create a new anchor element node createElement 4. Set the href attribute of the anchor setAttribute 5. Create a new text node with the word “source” createTextNode 6. Insert the text into the anchor appendChild 7. Insert the anchor into the blockquote. appendChild IN CONTROL 2009 25

FUNDAMENTAL JAVASCRIPT The code var quotes = document.getElementsByTagName( 'blockquote' ); for( var i=0; i < quotes.length; i++ ){ var source = quotes[i].getAttribute( 'cite' ); if( source ){ var link = document.createElement( 'a' ); link.setAttribute( 'href', source ); var text = document.createTextNode( 'source' ); link.appendChild( text ); quotes[i].appendChild( link ); } } IN CONTROL 2009 26

FUNDAMENTAL JAVASCRIPT The code var quotes = document.getElementsByTagName( 'blockquote' ); for( var i=0; i < quotes.length; i++ ){ var source = quotes[i].getAttribute( 'cite' ); if( source ){ var link = document.createElement( 'a' ); link.setAttribute( 'href', source ); var text = document.createTextNode( 'source' ); link.appendChild( text ); var para = document.createElement( 'p' ); para.className = 'attribution'; para.appendChild( link ); quotes[i].appendChild( para ); } } IN CONTROL 2009 27

FUNDAMENTAL JAVASCRIPT The code function sourceQuotes(){ var quotes = document.getElementsByTagName( 'blockquote' ); for( var i=0; i < quotes.length; i++ ){ var source = quotes[i].getAttribute( 'cite' ); if( source ){ var link = document.createElement( 'a' ); link.setAttribute( 'href', source ); var text = document.createTextNode( 'source' ); link.appendChild( text ); var para = document.createElement( 'p' ); para.className = 'attribution'; para.appendChild( link ); quotes[i].appendChild( para ); } } } window.onload = sourceQuotes; IN CONTROL 2009 28

FUNDAMENTAL JAVASCRIPT The result Progressive Enhancement, as a label for a strategy for Web design, was coined by Steven Champeon in a series of articles and presentations for Webmonkey and the SxSW Interactive conference. IN CONTROL 2009 29

FUNDAMENTAL JAVASCRIPT The result Progressive Enhancement, as a label for a strategy for Web design, was coined by Steven Champeon in a series of articles and presentations for Webmonkey and the SxSW Interactive conference. source IN CONTROL 2009 30

PROGRESSIVE ENHANCEMENT

WHAT IS PROGRESSIVE ENHANCEMENT?

PROGRESSIVE ENHANCEMENT VS. GRACEFUL DEGRADATION

GRACEFUL DEGRADATION

FUNDAMENTAL JAVASCRIPT Graceful Degradation ๏ A holdover from engineering ๏ Build for the latest browsers ๏ Test on older devices ‣ Happens at the end ‣ Accounts for few versions ๏ Expects a poor experience for older browsers ๏ Fixes major issues but little else IN CONTROL 2009 34

WEB STANDARDS: FUELING INNOVATION WEB BUILDER 2.0 35

PROGRESSIVE ENHANCEMENT FOCUSES ON CONTENT

CONTENT IS WHY WE BUILD WEBSITES AND SHOULD BE OUR CENTRAL FOCUS

HOW DOES IT WORK?

FUNDAMENTAL JAVASCRIPT Flavorful nugget of content (semantic goodness) IN CONTROL 2009 42

FUNDAMENTAL JAVASCRIPT Rich, indulgent design IN CONTROL 2009 43

FUNDAMENTAL JAVASCRIPT Sweet interactivity (keeps it from melting in your hands) IN CONTROL 2009 44

TECHNOLOGIES APPLIED AS LAYERS

WEB STANDARDS: FUELING INNOVATION stuffandnonsense.co.uk/archives/web_standards_trifle.html WEB BUILDER 2.0 48

WHY A PEANUT M&M?

FUNDAMENTAL JAVASCRIPT The peanut is good for ๏ diabetics IN CONTROL 2009 50

FUNDAMENTAL JAVASCRIPT The peanut is good for ๏ diabetics ๏ search engine spiders IN CONTROL 2009 50

FUNDAMENTAL JAVASCRIPT The peanut is good for ๏ diabetics ๏ search engine spiders ๏ mobile devices IN CONTROL 2009 50

IT’S A BASIC LEVEL OF SUPPORT

FUNDAMENTAL JAVASCRIPT The chocolate is good for IN CONTROL 2009 52

FUNDAMENTAL JAVASCRIPT The chocolate is good for ๏ diabetics IN CONTROL 2009 52

FUNDAMENTAL JAVASCRIPT Rich, chocolaty goodness ๏ some browsers only handle a certain level of CSS ๏ some companies turn off JavaScript IN CONTROL 2009 52

IT CAN BE BEAUTIFUL (and progressive)

FUNDAMENTAL JAVASCRIPT The candy coating IN CONTROL 2009 54

FUNDAMENTAL JAVASCRIPT The candy coating ๏ JavaScript can turn a website into an experience IN CONTROL 2009 54

FUNDAMENTAL JAVASCRIPT The candy coating ๏ JavaScript can turn a website into an experience ๏ we can deliver our scripts a la carte IN CONTROL 2009 54

PROGRESSIVE ENHANCEMENT WITH JAVASCRIPT

RESTRAINT & PLANNING

FUNDAMENTAL JAVASCRIPT A long time ago, in a cubicle far, far away... Dear George Lucas, please don’t sue me. Kthxbye. IN CONTROL 2009 57

WHAT CAN JAVASCRIPT DO?

HOW SHOULD JAVASCRIPT BE USED?

PROGRESSIVE ENHANCEMENT REMINDS US TO FOCUS ON THE CONTENT

FUNDAMENTAL JAVASCRIPT Back to basics IN CONTROL 2009 60

FUNDAMENTAL JAVASCRIPT Back to basics XHTML + HTTP IN CONTROL 2009 60

FUNDAMENTAL JAVASCRIPT Back to basics solid foundation IN CONTROL 2009 60

FUNDAMENTAL JAVASCRIPT ALL CODE NEEDED TO UNDERSTAND AND USE A SITE SHOULD EXIST BEFORE ANY SCRIPTS RUN IN CONTROL 2009 61

FUNDAMENTAL JAVASCRIPT PERIOD. IN CONTROL 2009 61

FUNDAMENTAL JAVASCRIPT Consider lala.com IN CONTROL 2009 62

FUNDAMENTAL JAVASCRIPT Without JavaScript IN CONTROL 2009 63

FUNDAMENTAL JAVASCRIPT Without JavaScript Doh! IN CONTROL 2009 63

FUNDAMENTAL JAVASCRIPT And looking at the IN CONTROL 2009 64

FUNDAMENTAL JAVASCRIPT And looking at the Ug h ! IN CONTROL 2009 64

WHAT ABOUT SEARCH?

WHAT ABOUT ALTERNATIVE DEVICES?

ENTER UNOBTRUSIVE JAVASCRIPT

ENTER UNOBTRUSIVE JAVASCRIPT ( ) the cornerstone of Progressive Enhancement with JavaScript

FUNDAMENTAL JAVASCRIPT Don’t do this <a href=quot;javascript:someFunction();quot;>some text</a> or <a href=quot;javascript:void(null);quot; onclick=quot;someFunction();quot;>some text</a> or <a href=quot;#quot; onclick=quot;someFunction();quot;>some text</a> IN CONTROL 2009 67

FUNDAMENTAL JAVASCRIPT An improvement, but still... <a href=quot;http://offsite.comquot; onclick=quot;newWin( this.href ); return false;quot;> some text</a> IN CONTROL 2009 68

FUNDAMENTAL JAVASCRIPT Getting warmer... window.onload = handleExternalLinks; function handleExternalLinks(){ var server = document.location.hostname; var anchors = document.getElementsByTagName(quot;aquot;); var i, href; for( i=0; i < anchors.length; i++ ){ href = anchors[i].href; if( href.indexOf(quot;http://quot; + server) == -1 && href.indexOf(quot;https://quot; + server) == -1 ){ // HREF is not a file on my server anchors[i].onclick = function(){ newWin( this.href ); }; } } } IN CONTROL 2009 69

FUNDAMENTAL JAVASCRIPT You’re hot document.getElementsByTagName( 'body' )[0] .onclick = clickDelegator; function clickDelegator( e ){ e = ( e ) ? e : event; var el = e.target || e.srcElement; // external links if( el.nodeName.toLowerCase() == 'a' && el.getAttribute( 'rel' ) == 'external' ){ newWin( el.href ); } } IN CONTROL 2009 70

JavaScript CSS

FUNDAMENTAL JAVASCRIPT Remember stuff like this? <a href=quot;foo.htmlquot; style=quot;color:blue;quot; onmouseover=quot;this.style.color='red'quot; onmouseout=quot;this.style.color='blue'quot;>Foo</a> IN CONTROL 2009 73

FUNDAMENTAL JAVASCRIPT Remember stuff like this? <a href=quot;foo.htmlquot; style=quot;color:blue;quot; onmouseover=quot;this.style.color='red'quot; onmouseout=quot;this.style.color='blue'quot;>Foo</a> Obvisouly, we should be doing this instead: a, a:link, a:visited { color: blue; } a:hover { color: red; } IN CONTROL 2009 73

FUNDAMENTAL JAVASCRIPT Isn’t this the same? for( i=0; i<objects.length; i++){ objects[i].style.display = 'none'; } IN CONTROL 2009 74

FUNDAMENTAL JAVASCRIPT Small improvement for( i=0; i<objects.length; i++){ objects[i].style.position = 'absolute'; objects[i].style.left = '-999em'; } IN CONTROL 2009 75

FUNDAMENTAL JAVASCRIPT Separation CSS: .hidden { position: absolute; left: -999em; } JavaScript: for( i=0; i<objects.length; i++){ objects[i].addClassName( 'hidden' ); } IN CONTROL 2009 76

FUNDAMENTAL JAVASCRIPT Maintenance options ๏ external style rules added to your CSS file (by hand) ๏ external CSS file added to the document (by hand) ๏ external CSS file added to the document via script ๏ embedding CSS in the document via script IN CONTROL 2009 77

FUNDAMENTAL JAVASCRIPT Option 1: Add by hand At the end of your screen layout CSS ﬁle: /* =START WickedCool Script CSS (do not remove) */ .wicked { color: red; font: bold 4em/2 quot;Comic Sansquot;; } .cool { color: blue; font: bold 4em/2 quot;Comic Sansquot;; } /* =END WickedCool Script CSS */ IN CONTROL 2009 78

FUNDAMENTAL JAVASCRIPT Option 2: Include by hand Added to the head of your document: <script type=quot;text/javascriptquot; src=quot;WickedCool.jsquot;></script> <link rel=quot;stylesheetquot; type=quot;text/cssquot; media=quot;screenquot; href=quot;WickedCool.cssquot; /> IN CONTROL 2009 79

FUNDAMENTAL JAVASCRIPT Option 3: Scripted include function FindPath( filename ){ var path = false; var scripts = document.getElementsByTagName( 'script' ); for( var i=0; i<scripts.length; i++ ){ if( scripts[i].getAttribute( 'src' ) && scripts[i].getAttribute( 'src' ) .indexOf( filename ) != -1 ){ path = scripts[i].getAttribute( 'src' ) .replace( new RegExp( filename ), '' ); break; } } return path; } IN CONTROL 2009 80

FUNDAMENTAL JAVASCRIPT Option 3: Scripted include var WickedCool = { jsFile: 'WickedCool.js', cssFile: 'WickedCool.css', basePath: false, initialize: function(){ // determine the path this.basePath = FindPath( this.jsFile ); // add the CSS file var css = document.createElement( 'link' ); css.setAttribute( 'rel', 'stylesheet' ); css.setAttribute( 'type', 'text/css' ); css.setAttribute( 'media', 'screen' ); css.setAttribute( 'href', this.basePath + this.cssFile ); document.getElementsByTagName( 'head' )[0] .appendChild( css ); // do the rest of the wicked cool stuff } }; IN CONTROL 2009 81

FUNDAMENTAL JAVASCRIPT Option 4: Scripted embed function addCSS( styles ){ var el = document.createElement( 'style' ); el.setAttribute( 'type', 'text/css' ); if( el.styleSheet ){ el.styleSheet.cssText = styles; } else { el.appendChild( document.createTextNode( styles ) ); } document.getElementsByTagName( 'head' )[0] .appendChild( el ); } based on the work of Nicholas Zakas IN CONTROL 2009 82

FUNDAMENTAL JAVASCRIPT Option 4: Scripted embed var WickedCool = { _css: '.wicked { color: red; ' + ' font: bold 4em/2 quot;Comic Sansquot;; } ' + '.cool { color: blue; ' + ' font: bold 4em/2' quot;Comic Sansquot;; }', initialize: function(){ // add the CSS addCSS( this._css ); // do the rest of the wicked cool stuff } }; based on the work of Nicholas Zakas IN CONTROL 2009 83

BUT KEEP IN MIND

YOU NEED TO AVOID APPLYING SCRIPT-RELATED STYLES

UNTIL YOU KNOW YOUR SCRIPT CAN RUN AND IT HAS INITIALIZED PROPERLY

FUNDAMENTAL JAVASCRIPT How do we do that? ๏ make your style rules speciﬁc: .TabInterface-folder { ... } or #TabInterface .tab { ... } #TabInterface .tab.active { ... } IN CONTROL 2009 85

FUNDAMENTAL JAVASCRIPT How do we do that? <div id=quot;mainquot; class=quot;tabbedquot;> becomes <div id=quot;mainquot; class=quot;tabbed-onquot;> IN CONTROL 2009 86

FUNDAMENTAL JAVASCRIPT How do we do that? Default Activated add “-on” to the class .tabbed .tabbed-on add an activation class .auto-submit .auto-submit.active change the form of the class .replace-me .replaced IN CONTROL 2009 86

FUNDAMENTAL JAVASCRIPT Look for methods function someFunction(){ if( !document.getElementsByTagName ) return; // code that uses document.getElementsByTagName() ... } IN CONTROL 2009 88

FUNDAMENTAL JAVASCRIPT Look for methods function someFunction(){ if( !document.getElementsByTagName || !document.getElementById ) return; /* code that uses document.getElementsByTagName() and document.getElementById() */ } IN CONTROL 2009 89

FUNDAMENTAL JAVASCRIPT Look for elements function someFunction(){ if( !document.getElementsByTagName || !document.getElementsByTagName( 'p' ) ) return; /* code that uses document.getElementsByTagName() and requires the presence of a P element */ ... } IN CONTROL 2009 90

FUNDAMENTAL JAVASCRIPT Look for identiﬁed elements function someFunction(){ if( !document.getElementById || !document.getElementById( 'content' ) ) return; // code that requires the presence of #content ... } IN CONTROL 2009 91

FUNDAMENTAL JAVASCRIPT Look for objects function someFunction(){ if( typeof( Prototype ) == 'undefined' ) return; // code that uses Prototype ... } IN CONTROL 2009 92

FUNDAMENTAL JAVASCRIPT Look for object versions function someFunction(){ if( typeof( jQuery ) == 'undefined' || parseFloat( jQuery.jquery ) < 1.2 ) return; // code that uses jQuery 1.2 or higher ... } IN CONTROL 2009 93

FUNDAMENTAL JAVASCRIPT Look before you leap window.onload = function(){ if( document.getElementsByTagName && document.getElementById ){ someFunction(); } }; IN CONTROL 2009 94

FUNDAMENTAL JAVASCRIPT PE with JavaScript ๏ Start with the content, then work your way out ๏ Get unobtrusive ๏ Keep some distance between your styles & your scripts ๏ Always wear your detective hat IN CONTROL 2009 95

HOW DOES IT ALL COME TOGETHER?

FUNDAMENTAL JAVASCRIPT Example 1: Tab Interface IN CONTROL 2009 97

FUNDAMENTAL JAVASCRIPT Traditional approach <h1>Pumpkin Pie</h1> <div class=quot;containerquot;> <div class=quot;sectionquot;> <h2>Overview</h2> <img src=quot;pie.jpgquot; alt=quot;quot;> <p>Whether you're hosting a festive party or a casual get-together with friends, our Pumpkin Pie will make entertaining easy!</p> ... </div> ... <ul class=quot;tabsquot;> <li><a href=quot;#quot;>Overview</a></li> <li><a href=quot;#quot;>Ingredients</a></li> <li><a href=quot;#quot;>Directions</a></li> <li><a href=quot;#quot;>Nutrition</a></li> </ul> </div> IN CONTROL 2009 98

FUNDAMENTAL JAVASCRIPT No style IN CONTROL 2009 99

FUNDAMENTAL JAVASCRIPT A little typography IN CONTROL 2009 100

FUNDAMENTAL JAVASCRIPT Typography & color IN CONTROL 2009 101

FUNDAMENTAL JAVASCRIPT No style IN CONTROL 2009 102

FUNDAMENTAL JAVASCRIPT No style .tabbed IN CONTROL 2009 102

FUNDAMENTAL JAVASCRIPT The actual source <h1>Pumpkin Pie</h1> <div class=quot;tabbedquot;> <h2>Overview</h2> <img src=quot;pie.jpgquot; alt=quot;quot; /> <p>Whether you're hosting a festive party or a casual get-together with friends, our Pumpkin Pie will make entertaining easy!</p> ... <h2>Ingredients</h2> <ul> <li>1 (9<abbr title=quot;inchquot;>in</abbr>) unbaked deep dish pie crust</li> <li>½ cup white sugar</li> <li>1 <abbr title=quot;teaspoonquot;>tsp</abbr> ground cinnamon</li> ... </ul> <h2>Directions</h2> ... </div> IN CONTROL 2009 103

FUNDAMENTAL JAVASCRIPT Understanding the ﬂow IN CONTROL 2009 104

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ // Public Properties this.Version = '0.3'; // version // Private Properties var _i = i; // incrementor var _cabinet = el; // the quot;cabinetquot; element (container) var _id = false; // ID of _cabinet var _active = false; // ID of the active quot;folderquot; var _tag = false; // tag we'll split it on // the tab list var _index = document.createElement( 'ul' ); // prototype elements var _els = { li: document.createElement( 'li' ), div: document.createElement( 'div' ) }; // methods to go here }; IN CONTROL 2009 105

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ ... function initialize(){ // code to come } function addClassName( e, c ){ var classes = ( !e.className ) ? [] : e.className.split( ' ' ); classes.push( c ); e.className = classes.join( ' ' ); } function removeClassName( e, c ){ var classes = e.className.split( ' ' ); for( var i=classes.length-1; i>=0; i-- ){ if( classes[i] == c ) classes.splice( i, 1 ); } e.className = classes.join( ' ' ); } // start it up initialize(); }; IN CONTROL 2009 106

FUNDAMENTAL JAVASCRIPT THE CODE function TabInterface( el, i ){ function initialize(){ // set the id _id = el.getAttribute( 'id' ) || 'folder-' + _i; if( !el.getAttribute( 'id' ) ) el.setAttribute( 'id', _id ); // trim whitespace var node = _cabinet.firstChild; while( node ){ var nextNode = node.nextSibling; if( node.nodeType == 3 && !/S/.test( node.nodeValue ) ) _cabinet.removeChild( node ); node = nextNode; } } ... }; IN CONTROL 2009 107

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ function initialize(){ ... // find the first heading var headers = [ 'h1', 'h2', 'h3', 'h4', 'h5', 'h6' ]; var hLen = headers.length; for( var i=0; i<hLen; i++ ){ if( _cabinet.firstChild.nodeName.toLowerCase() == headers[i] ){ _tag = headers[i]; break; } } } ... }; IN CONTROL 2009 108

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ function initialize(){ ... // establish the folders var rexp = new RegExp( '<(' + _tag + ')', 'ig' ); var arr = _cabinet.innerHTML.replace( rexp, quot;||||<$1quot; ).split( '||||' ); arr.shift(); _cabinet.innerHTML = ''; removeClassName( _cabinet, 'tabbed' ); addClassName( _cabinet, 'tabbed-on' ); } ... }; IN CONTROL 2009 109

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ function initialize(){ ... for( var k=0, aLen = arr.length; k<aLen; k++ ){ // build the div var folder = _els.div.cloneNode( true ); addClassName( folder, 'folder' ); folder.setAttribute( 'id', _id + '-' + k ); folder.innerHTML = arr[k]; _cabinet.appendChild( folder ); // build the tab var tab = _els.li.cloneNode( true ); tab.folder = folder.getAttribute( 'id' ); tab.setAttribute( 'id', tab.folder + '-tab' ); tab.onclick = swap; // set the action var heading = folder.getElementsByTagName( _tag )[0]; tab.innerHTML = heading.innerHTML; addClassName( heading, 'hidden' ); _index.appendChild( tab ); } } ... IN CONTROL 2009 110

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ function initialize(){ ... for( var k=0, aLen = arr.length; k<aLen; k++ ){ ... // active? if( k == 0 ){ addClassName( folder, 'visible' ); _active = folder.getAttribute( 'id' ); addClassName( tab, 'active-tab' ); } } // add the index _index.className = 'tab-list'; _cabinet.appendChild( _index ); } ... }; IN CONTROL 2009 111

FUNDAMENTAL JAVASCRIPT The code function TabInterface( el, i ){ ... function swap( e ){ e = ( e ) ? e : event; var tab = e.target || e.srcElement; removeClassName( document.getElementById( _active + '-tab' ), 'active-tab' ); removeClassName( document.getElementById( _active ), 'visible' ); addClassName( tab, 'active-tab' ); addClassName( document.getElementById( tab.folder ), 'visible' ); _active = tab.folder; } ... }; IN CONTROL 2009 112

FUNDAMENTAL JAVASCRIPT Greater ﬂexibility function TabInterface( el, i ){ function initialize(){ ... for( var k=0, aLen = arr.length; k<aLen; k++ ){ ... var heading = folder.getElementsByTagName( _tag )[0]; tab.innerHTML = heading.innerHTML; if( heading.getAttribute( 'title' ) ){ addClassName( heading, 'hidden' ); tab.innerHTML = heading.getAttribute( 'title' ) _index.appendChild( tab ); } else { ... tab.innerHTML = heading.innerHTML; } addClassName( heading, 'hidden' ); } } ... _index.appendChild( tab ); }; ... } } ... }; IN CONTROL 2009 113

FUNDAMENTAL JAVASCRIPT Greater ﬂexibility function TabInterface( el, i ){ function initialize(){ ... for( var k=0, aLen = arr.length; k<aLen; k++ ){ ... var heading = folder.getElementsByTagName( _tag )[0]; if( heading.getAttribute( 'title' ) ){ tab.innerHTML = heading.getAttribute( 'title' ) } else { tab.innerHTML = heading.innerHTML; addClassName( heading, 'hidden' ); } _index.appendChild( tab ); ... } } ... }; IN CONTROL 2009 113

FUNDAMENTAL JAVASCRIPT Running it // Load up TabInterface if( document.getElementById && document.getElementsByTagName && document.createElement ){ var cabinets = Array(); addDOMLoadEvent( function(){ var collection = document.getElementsByTagName( '*' ); for( var i=0, cLen = collection.length; i<cLen; i++ ){ if( collection[i] && /s*tabbeds*/.test( collection[i].className ) ){ cabinets.push( new TabInterface( collection[i], i ) ); } } } ); } IN CONTROL 2009 114

FUNDAMENTAL JAVASCRIPT The full experience IN CONTROL 2009 115

QUESTIONS?

FUNDAMENTAL JAVASCRIPT Example 2: Collapsing Form IN CONTROL 2009 117

FUNDAMENTAL JAVASCRIPT Collapsing Form as HTML IN CONTROL 2009 118

FUNDAMENTAL JAVASCRIPT Collapsing Form with CSS IN CONTROL 2009 119

FUNDAMENTAL JAVASCRIPT HTML hooks IN CONTROL 2009 122

FUNDAMENTAL JAVASCRIPT HTML hooks form.collapsing IN CONTROL 2009 122

FUNDAMENTAL JAVASCRIPT HTML hooks fieldset.optional IN CONTROL 2009 122

FUNDAMENTAL JAVASCRIPT Understanding the ﬂow IN CONTROL 2009 123

FUNDAMENTAL JAVASCRIPT The code var Easy = { addClassName: function( e, c ){ var classes = ( !e.className ) ? [] : e.className.split( ' ' ); classes.push( c ); e.className = classes.join( ' ' ); }, removeClassName: function( e, c ){ var classes = e.className.split( ' ' ); for( var i=classes.length-1; i>=0; i-- ){ if( classes[i] == c ) classes.splice( i, 1 ); } e.className = classes.join( ' ' ); }, hasClassName: function( e, c ){ var classes = e.className.split( ' ' ); for( var i=classes.length-1; i>=0; i-- ){ if( classes[i] == c ) return true; } return false; } }; IN CONTROL 2009 124

FUNDAMENTAL JAVASCRIPT The code var CollapsingForm = Class.create(); CollapsingForm.prototype = { link: document.createElement( 'a' ), linkText: [ document.createTextNode( 'More options' ), document.createTextNode( 'Fewer options' ) ], hidden: [], state: false, id: false, }; IN CONTROL 2009 125

FUNDAMENTAL JAVASCRIPT The code CollapsingForm.prototype = { ... initialize: function( form, i ){ // set the id this.id = i; // get the fieldsets var coll = form.getElementsByTagName( 'fieldset' ); // look for hiddens var hide = false; for( var i=coll.length-1; i>=0; i-- ){ if( coll[i].className.indexOf( 'hide-me' ) != -1 ){ hide = true; Easy.addClassName( coll[i], 'hidden' ); Easy.removeClassName( coll[i], 'hide-me' ); this.hidden.push( coll[i] ); } } // more to come } }; IN CONTROL 2009 126

FUNDAMENTAL JAVASCRIPT The code CollapsingForm.prototype = { ... initialize: function( form, i ){ ... // stop if no hiddens if( hide === false ) return; this.state = 'less'; // create & append the link to the first fieldset this.link = document.createElement( 'a' ); this.link.className = 'show-hide-link'; this.link.setAttribute( 'href', '#' ); Event.observe( this.link, 'click', this.toggle.bindAsEventListener( this ), false ); this.link.appendChild( this.linkText[0] ); coll[0].appendChild( this.link ); Easy.addClassName( form, 'collapsible' ); Easy.removeClassName( form, 'collapsing' ); } }; IN CONTROL 2009 127

FUNDAMENTAL JAVASCRIPT The code CollapsingForm.prototype = { initialize: function( form, i ){ ... }, toggle: function(){ if( this.state == 'less' ){ this.showMore(); } else { this.showLess(); } }, showMore: function(){ // code to come }, showLess: function(){ // code to come } }; IN CONTROL 2009 128

FUNDAMENTAL JAVASCRIPT The code CollapsingForm.prototype = { ... showMore: function(){ for( var i=0; i<this.hidden.length; i++ ){ Easy.removeClassName( this.hidden[i], 'hidden' ); } this.link.replaceChild( this.linkText[1], this.link.childNodes[0] ); this.state = 'more'; }, showLess: function(){ for( var i=0; i<this.hidden.length; i++ ){ Easy.addClassName( this.hidden[i], 'hidden' ); } this.link.replaceChild( this.linkText[0], this.link.childNodes[0] ); this.state = 'less'; } }; IN CONTROL 2009 129

FUNDAMENTAL JAVASCRIPT Collapsing Form with JS IN CONTROL 2009 130

QUESTIONS?

WORKING WITH LIBRARIES

FUNDAMENTAL JAVASCRIPT Popular Libraries ๏ jQuery (jquery.com) ๏ Prototype (prototypejs.org) & Scriptaculous (script.aculo.us) ๏ YUI (developer.yahoo.com/yui) ๏ Dojo (dojotoolkit.org) ๏ Spry (labs.adobe.com/technologies/spry) ๏ MooTools (mootools.net) ๏ MochiKit (mochikit.com) IN CONTROL 2009 133

FUNDAMENTAL JAVASCRIPT Popular Libraries ๏ jQuery - fast & easy to write, selector-based ๏ Prototype & Scriptaculous - powerful, Ruby-like ๏ YUI - powerful, backed by Yahoo! ๏ Dojo - powerful, backed by IBM ๏ Spry - supported in Dreamweaver, backed by Adobe ๏ MochiKit - powerful, Python-like IN CONTROL 2009 134

FUNDAMENTAL JAVASCRIPT Popular Libraries ๏ jQuery - fast & easy to write, selector-based ๏ Prototype & Scriptaculous - powerful, Ruby-like ๏ YUI - powerful, backed by Yahoo! IN CONTROL 2009 134

FUNDAMENTAL JAVASCRIPT Getters 2.0 ๏ jQuery: ‣ $(selector) ‣ $(selector).attr(attribute) ๏ Prototype: ‣ $(id) or $$(selector) ‣ $$(selector).readAttribute(attribute) ๏ YUI: ‣ YAHOO.util.Dom.get(id) or YAHOO.util.Selector.query(selector) ‣ YAHOO.util.Dom.getAttribute(element, attribute) IN CONTROL 2009 135

FUNDAMENTAL JAVASCRIPT Setters 2.0 ๏ jQuery: ‣ $(x).text(text) or $(x).html(html) or $(x).append([el|text]) ‣ $(x).attr([attr, value|map]) ๏ Prototype: ‣ $(x).insert([text|element]) // after by default ‣ $(x).writeAttribute([attr, value|map]) ๏ YUI: ‣ YAHOO.util.Dom.insertAfter( [str|el], reference) ‣ YAHOO.util.Dom.addClass(el, class) IN CONTROL 2009 136

LET’S REVISIT OUR FIRST EXAMPLE

FUNDAMENTAL JAVASCRIPT The page Progressive Enhancement, as a label for a strategy for Web design, was coined by Steven Champeon in a series of articles and presentations for Webmonkey and the SxSW Interactive conference. IN CONTROL 2009 139

FUNDAMENTAL JAVASCRIPT The code function sourceQuotes(){ var quotes = document.getElementsByTagName( 'blockquote' ); for( var i=0; i < quotes.length; i++ ){ var source = quotes[i].getAttribute( 'cite' ); if( source ){ var link = document.createElement( 'a' ); link.setAttribute( 'href', source ); var text = document.createTextNode( 'source' ); link.appendChild( text ); var para = document.createElement( 'p' ); para.className = 'attribution'; para.appendChild( link ); quotes[i].appendChild( para ); } } } window.onload = sourceQuotes; IN CONTROL 2009 140

FUNDAMENTAL JAVASCRIPT The optimized code ... var i, quotes = document.getElementsByTagName( 'blockquote' ), a = document.createElement( 'a' ), p = document.createElement( 'p' ); a.appendChild( document.createTextNode('source') ); p.className = 'attribution'; for( i=0; i < quotes.length; i++ ){ var source = quotes[i].getAttribute( 'cite' ); if( source ){ var link = a.cloneNode( true ); link.setAttribute( 'href', source ); var para = p.cloneNode( true ); para.appendChild( link ); quotes[i].appendChild( para ); } } ... IN CONTROL 2009 141

FUNDAMENTAL JAVASCRIPT In jQuery ... var $this, $p = $('<p class=quot;attributionquot;><a href=quot;#quot;>source</a></p>'); $('blockquote[cite]').each(function(){ $this = $(this).append( $p.clone() ); $this.find('.attribution a') .attr( 'href', $this.attr( 'cite' ) ); }); ... IN CONTROL 2009 142

FUNDAMENTAL JAVASCRIPT In Prototype ... var $el, $link, $para, $a = $( document.createElement('a') ).insert( 'source' ), $p = $( document.createElement('p') ).addClassName( 'attribution' ); $$('blockquote[cite]').each(function($el){ $link = $a.cloneNode( true ); $para = $p.cloneNode( true ); $link.writeAttribute( 'href', $el.readAttribute( 'cite' ) ); $para.insert( $link ); $el.insert( $para ); }); ... IN CONTROL 2009 143

FUNDAMENTAL JAVASCRIPT In YUI ... var i, $D = YAHOO.util.Dom, $ = YAHOO.util.Selector.query, quotes = $( 'blockquote[cite]' ), a = document.createElement( 'a' ), p = document.createElement( 'p' ); a.appendChild( document.createTextNode('source') ); $D.addClass( p, 'attribution' ); for( i=0; i < quotes.length; i++ ){ var link = a.cloneNode( true ); link.setAttribute( 'href', quotes[i].getAttribute( 'cite' ) ); var para = p.cloneNode( true ); para.appendChild( link ); quotes[i].appendChild( para ); } ... IN CONTROL 2009 144

FUNDAMENTAL JAVASCRIPT Running the function ๏ DOM: ‣ window.onload = sourceQuotes; ๏ jQuery: ‣ $(document).ready( sourceQuotes ); ‣ $( sourceQuotes ); ๏ Prototype: ‣ document.observe( 'dom:loaded', sourceQuotes ); ๏ YUI: ‣ YAHOO.util.Event.onDOMReady( sourceQuotes ); IN CONTROL 2009 145

FUNDAMENTAL JAVASCRIPT Keep in mind ๏ Helper/convenience methods are often shorter, but are sometimes less explicit (e.g. $()) ‣ Comment. Comment! COMMENT! ๏ Libraries often obscure what’s really going on under the hood and can make it more difficult to debug your code ‣ Read the source, learn what it’s doing for you ๏ Libraries trade off convenience for file size; they also often have numerous features you may never use ‣ If you can write something without a library and it works, don’t use a library ‣ Check for minified files and/or isolated modules IN CONTROL 2009 146

NOW GET OUT THERE AND WRITE SOMETHING COOL

FUNDAMENTAL JAVASCRIPT Aaron Gustafson Slides available at http://slideshare.net/AaronGustafson This presentation is licensed under Creative Commons Attribution-Noncommercial-Share Alike 3.0

Fundamental JavaScript [In Control 2009]

by Aaron Gustafson on May 27, 2009

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Fundamental JavaScript [In Control 2009] — Presentation Transcript

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