Learning Web Design Third Edition- P11 docx

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Learning Web Design Third Edition- P11 docx

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Part II: HTML Markup for Structure 86 Generic Elements (div and span) Generic Elements (div and span) There are endless types of information in the world, but as you’ve seen, not all that many semantic elements. Fortunately, (X)HTML provides two generic elements that can be customized to describe your content perfectly. The div (short for “division”) element is used to indicate a generic block-level ele- ment, while the span element is used to indicate a generic inline element. You give a generic element a name using either an id or class attribute (we’ll talk about those more in just a moment). The div and span elements have no inherent presentation qualities of their own, but you can use style sheets to format the content however you like. In fact, generic elements are a primary tool in standards-based web design because they enable authors to accurately describe content and offer plenty of “hooks” for adding style rules. We’re going to spend a little time on div and span (as well as the id and class attributes, also called element identifiers) because they will be powerful tools once we start working with Cascading Style Sheets. Let’s take a look at how authors use these elements to structure content. Divide it up with a div The div element is used to identify a block-level division of text. You can use a div like a container around a logical grouping of elements on the page. By marking related elements as a div and giving it a descriptive name, you give context to the elements in the grouping. That comes in handy for making the structure of your document clear but also for adding style properties. Let’s look at a few examples of div elements. In this example, a div element is used as a container to group an image and two paragraphs into a “listing”. <div class="listing"> <img src="felici.gif" alt="" /> <p><cite>The Complete Manual of Typography</cite>, James Felici</p> <p>A combination of type history and examples of good and bad type. </p> </div> By putting those elements in a div, I’ve made it clear that they are conceptu- ally related. It also allows me to style to p elements within listings differently than other paragraphs on the page. Here is another common use of a div used to break a page into sections for context, structure, and layout purposes. In this example, a heading and sev- eral paragraphs are enclosed in a div and identified as the “news” section. <div id="news"> <h1>New This Week</h1> <p>We've been working on </p> <p>And last but not least, </p> </div> <div> </div> Generic block-level element <span> </span> Generic inline element <div> </div> Generic block-level element <span> </span> Generic inline element It is possible to nest div elements within other div elements, but don’t go overboard. You should always strive to keep your markup as simple as possible, so only add a div element if it is necessary for logical structure or styling. m A R K U P t I P Generic Elements (div and span) Chapter 5, Marking Up Text 87 Now that I have an element known as “news,” I could use a style sheet to position it as a column to the right or left of the page. Get inline with span A span offers all the same benefits as the div element, except it is used for inline elements that do not introduce line breaks. Because spans are inline elements, they can only contain text and other inline elements (in other words, you cannot put block-level elements in a span). Let’s get right to some examples. In this example, each telephone number is marked up as a span and classified as “phone.” <ul> <li>Joan: <span class="phone">999.8282</span></li> <li>Lisa: <span class="phone">888.4889</span></li> <li>Steve: <span class="phone">888.1628</span></li> <li>Morris: <span class="phone">999.3220</span></li> </ul> You can see how the labeled spans add meaning to what otherwise might be a random string of digits. It makes the information recognizable not only to humans but to (theoretical) computer programs that know what to do with “phone” information. It also enables us to apply the same style to phone numbers throughout the site. Element identifiers In the previous examples, we saw the element identifiers, id and class, used to give names to the generic div and span elements. Each identifier has a spe- cific purpose, however, and it’s important to know the difference. The id identifier The id identifier is used to identify a unique element in the document. In other words, the value of id must be used only once in the document. This makes it useful for assigning a name to a particular element, as though it were a piece of data. See the sidebar, id and class Values, for information on providing names for the id attribute. This example uses the book’s ISBN number to uniquely identify each listing. No two book listings may share the same id. <div id="ISBN0321127307"> <img src="felici.gif" alt="" /> <p><cite>The Complete Manual of Typography</cite>, James Felici</p> <p>A combination of type history and examples of good and bad type.</ p> </div> Not Just for divs The id and class attributes may be used with nearly all (X)HTML elements, not just div and span . For example, you could identify an unordered list as “navigation” instead of wrapping it in a div . <ul id="navigation"> <li> </li> <li> </li> <li> </li> </ul> In HTML 4.01, id and class attributes may be used with all elements except base , basefont , head , html , meta , param , script , style , and title . In XHTML, id support has been added to those elements. Part II: HTML Markup for Structure 88 Generic Elements (div and span) <div id="ISBN0881792063"> <img src="bringhurst.gif" alt=" /"> <p><cite>The Elements of Typographic Style</cite>, Robert Bringhurst</p> <p>This lovely, well-written book is concerned foremost with creating beautiful typography.</p> </div> Web authors also use id when identifying the various sections of a page. With this method, there may not be more than one “header,” “main,” or other named div in the document. <div id="header"> (masthead and navigation here) </div> <div id="main"> (main content elements here) </div> <div id="links"> (list of links here) </div> <div id="news"> (news sidebar item here) </div> <div id="footer"> (copyright information here) </div> The class identifier The class attribute is used for grouping similar elements; therefore, unlike the id attribute, multiple elements may share a class name. By making ele- ments part of the same class, you can apply styles to all of the labeled ele- ments at once with a single style rule. Let’s start by classifying some elements in the earlier book example. In this first example, I’ve added class attributes to certain paragraphs to classify them as “descriptions.” <div id="ISBN0321127307" class="listing"> <img src="felici.gif" alt="" /> <p><cite>The Complete Manual of Typography</cite>, James Felici</p> <p class="description">A combination of type history and examples of good and bad type.</p> </div> <div id="ISBN0881792063" class="listing"> <img src="bringhurst.gif" alt="" /> <p><cite>The Elements of Typographic Style</cite>, Robert Bringhurst</p> <p class="description">This lovely, well-written book is concerned foremost with creating beautiful typography.</p> </div> I’ve also classified each div as a “listing.” Notice how the same element may have both a class and an id identifier. It is also possible for elements to The id attribute is used to identify . The class attribute is used to t I P id and class Values The values for id and class attributes should start with a letter (A-Z or a-z) or underscore (although Internet Explorer 6 and earlier have trouble with underscores, so they are generally avoided). They should not contain any character spaces or special characters. Letters, numbers, hyphens, underscores, colons, and periods are okay. Also, the values are case-sensitive, so “sectionB” is not interchangeable with “Sectionb.” Some Special Characters Chapter 5, Marking Up Text 89 belong to multiple classes. In this example, I’ve classified each div as a “book” to set them apart from “cd” or “dvd” listings elsewhere in the document. <div id="ISBN0321127307" class="listing book"> <img src="felici.gif" alt="CMT cover"> <p><cite>The Complete Manual of Typography</cite>, James Felici</p> <p class="description">A combination of type history and examples of good and bad type.</p> </div> <div id="ISBN0881792063" class="listing book"> <img src="bringhurst.gif" alt="ETS cover"> <p><cite>The Elements of Typographic Style</cite>, Robert Bringhurst</p> <p class="description">This lovely, well-written book is concerned foremost with creating beautiful typography.</p> </div> This should have given you a good introduction to how div and span are used to provide meaning and organization to documents. We’ll work with them even more in the style sheet chapters in Part III. Some Special Characters There’s just one more text-related topic before we move on. Some common characters, such as the copyright symbol ©, are not part of the standard set of ASCII characters, which contains only letters, numbers, and a few basic symbols. Other characters, such as the less-than symbol (<), are available, but if you put one in an (X)HTML document, the browser will interpret it as the beginning of a tag. Characters such as these must be escaped in the source document. Escaping means that instead of typing in the character itself, you represent it by its numeric or named character reference. When the browser sees the character reference, it substitutes the proper character in that spot when the page is displayed. There are two ways of referring to a specific character: by an assigned numeric value (numeric entity) or using a predefined abbreviated name for the character (called a named entity). All character references begin with a “&” and end with an “;”. Some examples will make this clear. I’d like to add a copyright symbol to my page. The typical Mac keyboard command, Option-G, which works in my word processing program, won’t work in XHTML. Instead, I must use the named entity &copy; (or its numeric equivalent &#169;) where I want the symbol to appear (Figure 5-12). <p>All content copyright &copy; 2007, Jennifer Robbins</p> or: <p>All content copyright &#169; 2007, Jennifer Robbins</p> Part II: HTML Markup for Structure 90 Some Special Characters (X)HTML defines hundreds of named entities as part of the markup lan- guage, which is to say you can’t make up your own entity. Table 5-4 lists some commonly used character references. If you’d like to see them all, the complete list of character references has been nicely assembled online by the folks at the Web Standards Project at www.webstandards.org/learn/reference/charts/ entities/. Table 5-4. Common special characters and their character references Character Description Name Number Character space (nonbreaking space) &nbsp; &#160; & Ampersand &amp; &#038; ' Apostrophe &apos; (XHTML only) &#039; < Less-than symbol (useful for dis- playing markup on a web page) &lt; &#060; > Greater-than symbol (useful for displaying markup on a web page) &gt; &$062; © Copyright &copy; &#169; ® Registered trademark &reg; &#174; ™ Trademark &trade; &#8482; £ Pound &pound; &#163; ¥ Yen &yen; &#165; € Euro &euro; &#8364; – En-dash &ndash; &#8211; — Em-dash &mdash; &#8212; ‘ Left curly single quote &lsquo; &#8216; ’ Right curly single quote &rsquo; &#8217; “ Left curly double quote &ldquo; &#8220; ” Right curly double quote &rdquo; &#8221; • Bullet &bull; &#8226; Horizontal ellipses &hellip; &#8230; Figure 5-12. The special character is substituted for the character reference when the document is displayed in the browser. Character References in XHTML There are a few ways in which XHTML is different than HTML when it comes to character references. First, XHTML defines a character entity for apostrophe ( &apos; ), that was curiously omitted from the HTML spec. In XHTML, every instance of an ampersand must be escaped so that it is not interpreted as the beginning of a character entity, even when it appears in the value of an attribute. For example, <img src="sno.jpg" alt="Sifl &amp; Olly Show" />   Non-breaking Spaces One interesting character to know about is the non-breaking space ( &nbsp; ). Its purpose is to ensure that a line doesn’t break between two words. So, for instance, if I mark up my name like this: Jennifer&nbsp;Robbins I can be sure that they will always stay together on a line. Non-breaking spaces are also commonly used to add a string of character spaces to text (remember that browsers ignore consecutive character spaces in the source document). But if it’s space you’re after, first consider whether a style sheet margin, padding, or white- space property might be a better option than a string of space characters. Putting It All Together Chapter 5, Marking Up Text 91 Putting It All Together So far, you’ve learned how to mark up elements and you’ve met all of the (X)HTML elements for adding structure and meaning to text content. Now it’s just a matter of practice. Exercise 5-3 gives you an opportunity to try out everything we’ve covered so far: document structure elements, block ele- ments, inline elements and character entities. Have fun! N ot e This text file is available online at www. learningwebdesign.com/materials. The resulting markup is in Appendix A. exercise 5-3 | Text markup practice Now that you’ve been introduced to all of the text elements, you can put them to work by marking up a menu for the Black Goose Bistro. The raw text is shown below. You can type it in or get the raw text file online (see note). Once you have the raw content, follow the instructions following the copy. The resulting page is shown in Figure 5-13. Black Goose Bistro | Summer Menu Baker’s Corner Seekonk, Massachusetts, Hours: M-T: 11 to 9, F-S; 11 to midnight Appetizers Black bean purses Spicy black bean and a blend of mexican cheeses wrapped in sheets of phyllo and baked until golden. $3.95 Southwestern napoleons with lump crab new item! Layers of light lump crab meat, bean and corn salsa, and our handmade flour tortillas. $7.95 Main courses Shrimp sate kebabs with peanut sauce Skewers of shrimp marinated in lemongrass, garlic, and fish sauce then grilled to perfection. Served with spicy peanut sauce and jasmine rice. $12.95 Grilled skirt steak with mushroom fricasee Flavorful skirt steak marinated in asian flavors grilled as you like it*. Served over a blend of sauteed wild mushrooms with a side of blue cheese mashed potatoes. $16.95 Jerk rotisserie chicken with fried plantains new item! Tender chicken slow-roasted on the rotisserie, flavored with spicy and fragrant jerk sauce and served with fried plantains and fresh mango. $12.95 * We are required to warn you that undercooked food is a health risk. Part II: HTML Markup for Structure 92 Putting It All Together Enter the document structure elements first. Give the document the title “Black Goose Bistro Summer Menu.” Use div elements to divide the page into four unique sections named “header,” “appetizers,” “main,” and “warnings,” in that order as appropriate. Identify the first- and second-level headings ( h1 and h2 ). In the first-level heading, change the vertical bar character to a bullet character. Make the restaurant information a paragraph. Delete the comma after “Massachusetts” and start “hours” on a new line with a br element. Choose the best list elements for the menu item listings (Appetizers and Main Courses). Mark up the lists and each item in them. Make the footnote at the bottom of the menu a paragraph. Make the asterisk for the footnote superscript. Make the asterisk in the menu description superscript as well. Two of the dishes are new items. Change the double hyphens to an em-dash character and strongly emphasize “new items!” Classify the title of each new dish as “newitem”. Classify each price as “price” using span elements. Label the paragraph in the “warnings” div as a “footnote” using a class identifier. Save the file and name it menu_summer. html (you can save it in the bistro directory you created in Chapter 4). Check your page in a browser. Markup tips: Choose the element that best fits the meaning of the selected text. Don’t forget to close elements with closing tags. Put all attribute values in quotation marks “Copy and paste” is your friend when adding the same markup to multiple elements. Just be sure what you copied is correct before you paste it throughout the document. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.     Figure 5-13. The finished menu page. Want More Practice? Try marking up your own résumé. Start with the raw text, then add document structure elements, block elements, then inline elements as we’ve done in Exercise 5-3. If you don’t see an element that matches your information just right, try creating one using a div or a span . Test Yourself Chapter 5, Marking Up Text 93 Test Yourself Were you paying attention? Here is a rapid-fire set of questions to find out. Add the markup to add a quick horizontal rule between these paragraphs. <p>People who know me know that I love to cook.</p> <p>I’ve created this site to share some of my favorite recipes.</p> What does “deprecated” mean? What’s the difference between a blockquote and a q element? What element displays white space exactly as it is typed into the source document? What is the difference between a ul and an ol? How do you remove the bullets from an unordered list? (Be general, not specific.) What element would you use to provide the full name of the W3C in the document? Can you write out the complete markup? What is the difference between a dl and a dt? What is the difference between id and class? Name the characters generated by these character entities: &mdash; ___________ &amp; ___________ &nbsp; ___________ &copy; ___________ &bull; ___________ &trade; ___________ 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Part II: HTML Markup for Structure 94 (X)HTML Review: Text Elements (X)HTML Review: Text Elements The following is a summary of the elements we covered in this chapter. Block-level elements address author contact address blockquote blockquote h1 h6 headings p paragraph hr horizontal rule List elements (block-level) dd definition dl definition list dt term li list item (for ul and ol) ol ordered list ul unordered list Semantic inline elements abbr abbreviation acronym acronym cite citation code code sample del deleted text dfn defining term em emphasized text ins inserted text kbd keyboard text q short quotation samp sample output strong strongly emphasized var variable Presentational inline elements b bold big big br line break center centered text font size, color, face i italic s strike-through small small text strike strike-through sub subscript sup superscript tt teletype u underlined Generic elements div block-level division span inline span of text 95 IN THIS CHAPTER Making links to external pages Making relative links to documents on your own server Linking to a specific point in a page Adding “mailto” links Targeting new windows If you’re creating a page for the Web, chances are you’ll want it to point to other web pages, whether to another section of your own site or to someone else’s. You can even link to another spot on the same page. Linking, after all, is what the Web is all about. In this chapter, we’ll look at the markup that makes links work: to other sites, to your own site, and within a page. If you’ve used the Web at all, you should be familiar with the highlighted text and graphics that indicate “click here.” There is one element that makes linking possible: the anchor (a). <a> </a> Anchor element (hypertext link) The content of the anchor element becomes the hypertext link. Simply wrap a selection of text in opening and closing <a> </a> tags and use the href attribute to provide the URL of the linked page. Here is an example that cre- ates a link to the O’Reilly Media web site: <a href="http://www.oreilly.com">Go to O'Reilly.com</a> To make an image a link, simply put the img element in the anchor element: <a href="http://www.oreilly.com"><img src="ora.gif" /></a> The only restriction is that because anchors are inline elements, they may only contain text and other inline elements. You may not put a paragraph, heading, or other block element between anchor tags. Most browsers display linked text as blue and underlined, and linked images with a blue border. Visited links generally display in purple. Users can change these colors in their browser preferences, and, of course, you can change the appearance of links for your sites using style sheets. I’ll show you how in Chapter 13, Colors and Backgrounds. When a user clicks on the linked text or image, the page you specify in the anchor element loads in the browser window. The linked image markup sample shown previously might look like Figure 6-1. ADDING LINKS CHAPTER 6 Anchor Syntax The simplified structure of the anchor element is: <a href="url">linked text or image</a> A t A G l A n c e . elements and character entities. Have fun! N ot e This text file is available online at www. learningwebdesign.com/materials. The resulting markup is in Appendix A. exercise 5-3 | Text markup. list of character references has been nicely assembled online by the folks at the Web Standards Project at www.webstandards.org/learn/reference/charts/ entities/. Table 5-4. Common special characters. Less-than symbol (useful for dis- playing markup on a web page) &lt; &#060; > Greater-than symbol (useful for displaying markup on a web page) &gt; &$062; © Copyright &copy;

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Mục lục

  • Learning Web Design

    • Preface

    • Part I Getting Started

      • Chapter 1

        • Where Do I Start?

          • Am I Too Late?

          • Where Do I Start?

          • What Do I Need to Learn?

          • Do I Need to Learn Java?

          • What Do I Need to Buy?

          • What You’ve Learned

          • Test Yourself

          • Chapter 2

            • How the Web Works

              • Serving Up Your Information

              • A Word About Browsers

              • Web Page Addresses (URLs)

              • The Anatomy of a Web Page

              • Putting It All Together

              • Test Yourself

              • Browser Versions

              • Chapter 3

                • The Nature of Web Design

                  • Alternative Browsing Environments

                  • User Preferences

                  • Different Platforms

                  • Connection Speed

                  • Browser Window Size and Monitor Resolution

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