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the seven CSS keywords directly to the seven Netscape font sizes. In many ways, it was a logical and even brilliant thing to do. (The IE/Windows devel- opers were also the first group to attempt to support absolute font size key- words. We should credit them for that before carping about the results.) The problem, of course, is that, logically, the sizes do not map to the key- words. In old-style browsers, <FONT SIZE=3> is the default or normal size that the user has specified in her preferences. In Netscape’s extended HTML markup, <FONT SIZE=3> is assumed unless you specify another size. Logi- cally, a default size should map to the “medium” CSS keyword. Unfortu- nately, in the IE/Windows scheme, <FONT SIZE=3> maps to “small” instead of “medium” because small is the third size up from the bottom of the list. Who goofed—the W3C or the IE/Windows team? It doesn’t really matter. What matters is that the keywords don’t map to expected sizes, and an incompatibility exists not only between different manufacturers’ browsers but between the Mac and Windows versions of the same browser. If you think of the seven sizes the way the IE/Windows team did, your sizes will be off on Mac users’ desktops. (You also will go nuts. It’s like trying to drive a car where Park means Neutral.) If you think of them the way the keywords actually read (small, medium, large) your display will be off in Windows. You can trick the Mac browser into emulating Windows behav- ior by specifying a <DOCTYPE> of HTML 4 Transitional and leaving off the W3C URL. (For details, see http://www.alistapart.com/stories/ie5mac. But this is forcing the browser to emulate nonstandard behavior, and that's not good. Besides, it won't work in Netscape 4, Opera, or Konqueror. So what can you do? Sadly, until your entire audeince uses browsers that render absolute keywords, all you can do is ignore the W3C recommenda- tions and use pixels in your style sheet. Or do not use sizes at all. Relative keywords Relative keywords are limited to two: smaller and larger. These in turn refer to the size of the parent element. For example, consider the following example, in which the <BODY> is 12px, and <BOLD> is “larger.” 281 Taking Your Talent to the Web 14 0732 CH10 4/24/01 1:04 PM Page 281 <HTML> <STYLE TYPE=”text/css”> <! BODY {font: 12px verdana, arial, geneva;} B {font-weight: bold; font-size: larger;} > </STYLE> Bold type would theoretically be 14px tall in this example because 14px is one “notch” up from 12px. Like absolute size keywords, relative keywords are ignored or bungled in some popular browsers (Explorer 3 ignores them, as does Navigator 4 for the Mac). And even if they worked correctly, they would be insufficient for the needs of most web designers and their clients. Normal, larger, and smaller is not exactly a robust vocabulary for the needs of professional designers. So what can you do? You can use pixels in your style sheet; that’s what you can do. Length units Length units sound smutty (those W3C folks should get out more…or maybe it’s just us) and include the following: ■ em—Is a unit of distance equal to the point size of a font. In 14pt. type, an em is 14pts. wide—named for the size of the capital “M.” But you knew that.) ■ ex—Refers to the height of lowercase letters. When used with the font-size property, em and ex units refer to the font size of the parent element. <HTML> <STYLE TYPE=”text/css”> <! BODY {font: 12px verdana, arial, geneva, sans-serif;} STRONG {font-weight: bold; font-size: 2em;} > </STYLE> 282 HOW: Style Sheets for Designers: Trouble in Paradise 14 0732 CH10 4/24/01 1:04 PM Page 282 In this example, <STRONG> would be 24px tall, or 2em (two times the font size of the parent element, which is the <BODY> tag). In theory, a web designer could create a layout using em or ex units, where all elements were sized relative to each other. This would avoid the accessibility prob- lems associated with pixels. Unfortunately, the browsers make this impossible for the time being. Netscape 4 ignores em and ex units. IE3 treats em units as pixels. Thus, 2em is mistranslated as 2 pixels tall. It takes a village to raise a child, and it takes at least 9 pixels to render a font. Length units are therefore not recom- mended. What is recommended? Pixels or nothing. Percentage units Percentage units, like length units and relative keywords, refer to the size of the parent element. <HTML> <STYLE TYPE=”text/css”> <! BODY {font: 12px verdana, arial, geneva, sans-serif;} STRONG {font-weight: bold; font-size: 200%;} > </STYLE> In this example, <STRONG> would be 24px tall, or 200% of the font size of the parent element, which is the <BODY> tag. In theory (notice how we keep saying “in theory"?), a web designer could create a layout using per- centages and avoid the accessibility problems associated with pixels. Nothing is sadder than the murder of a beautiful theory by a gang of ugly facts. Netscape 4 for Mac renders percentage units when they are used for line-height (leading) but ignores them entirely when they are used to spec- ify type sizes. And some versions of Netscape 4 for Windows treat per- centages as pixels. (Thus, 200% is dementedly translated as 200 pixels. Mmm, nice layout.) 283 Taking Your Talent to the Web 14 0732 CH10 4/24/01 1:04 PM Page 283 Lest we forget, good old IE3 drops the ball by sizing percentages relative to the user’s default font size rather than to the parent element. In Eng- lish: If the web user has set her browser’s default to 10px, IE3 will display <STRONG> at 20px and not the 24px you intended. If her browser defaults to 16px, <STRONG> will be 32px. Too bad for you. Too bad for your visitor. In spite of their accessibility benefits, percentages still fail in too many browsers. What works? Pixels—pixels or nothing. In case we’ve failed to communicate, we will summarize our findings as follows: Looking Forward Web designers will continue to be limited to using pixels in their style sheets—despite the accessibility hazards associated with that practice— until fully standards-compliant browsers exist and are widely used. The approach might have its drawbacks, but failure to work correctly is not one of them. As web designers, our job is to control the visitor’s visual experi- ence to communicate. For the time being, the approach outlined here will allow us to do exactly that. And soon enough, Lord (and browser compa- nies) willing, the full power of CSS will be ours. Can you take CSS further today? Quite possibly. It depends on the makeup of your audience and your salesmanship with clients. As explained in Chap- ter 13, A List Apart converted to an all-CSS layout in February 2001, and many sites have since followed suit. For details and encouragement, see http://www.alistapart.com/stories/99. 284 HOW: Style Sheets for Designers: Trouble in Paradise 14 0732 CH10 4/24/01 1:04 PM Page 284 chapter 11 The Joy of JavaScript WE’VE SAID ALL ALONG that the Web is not print. If you’ve harbored lingering doubts on that score, this chapter should clear them up pronto. If this chapter does not clear them up, try club soda and a semiabrasive cloth. A primary reason the Web is not print is that websites don’t just sit there; they do things—responding to clicks of the mouse, hovering motions, and other user activities. JavaScript is behind much of that interactivity. In JavaScript parlance, user actions such as mouse clicks are called events, and you handle them via event handlers (“onClick,” for example). Similarly, in JavaScript, the components of a web page, such as GIF images and form buttons, are considered objects. Web pages are known as documents, and the whole shebang is held together by a Document Object Model (DOM). See, it’s not that hard, and you are learning already. In this chapter you’ll find out what JavaScript is, where it came from, how it brings websites to life, where to learn all about it, and how to begin using it even before you learn all about it. You’ll also learn how to communicate desired JavaScript functions to the developers on your team, who will handle the heavy scripting when it is needed. If you freelance or work in a graphic design shop instead of a web agency, you’ll learn how to communicate with freelance programmers. But before you can begin doing any of that, a few basics are in order. 15 0732 CH11 4/24/01 11:23 AM Page 285 WHAT IS THIS THING CALLED JAVASCRIPT? JavaScript is a programming language designed specifically to work in web browsers. Its purpose is to bring interactivity to sites. Though JavaScript is powerful and complex, it is relatively easy to learn—at least it is easier to learn than many other programming languages. Even before JavaScript, sites could be somewhat interactive. After all, click- ing a hyperlink loads a new page. The nonlinear nature of hypertext allows the reader to decide where to go next—to structure her own voyage through the site (and, indeed, through the Web). That is an interactive process and a rather profound one. But it is not a ter- ribly sophisticated form of interactivity. JavaScript puts the top hat and tails on web interactivity. The Web Before JavaScript Before JavaScript, programming languages such as Perl were used to facil- itate interactive processes, for example typing text into a form and click- ing a button, thereby sending requested information to the site’s owners. Perl is still often used for this purpose on a great many sites. But Perl is a server-side scripting language. That is, when a visitor clicks the Send button, the web server itself must process the script. If the server goes down or malfunctions, nothing will happen. Likewise, a web page not con- nected to a web server—say, a web page on your hard drive—would not be able to process such a script except in special circumstances (permanent Net connection, full URL specified in the <FORM ACTION>, burning of incense, wearing of magic ring). While the script is being processed, the web server is momentarily tied up— just as your Mac or PC gets tied up when you apply motion blur to an image in Photoshop. Imagine constantly applying motion blur while receiving and sending email, and you begin to see what web servers were up against. (This is, of course a crude picture, and if you like it, we have other crude pictures available at a nominal price.) 286 HOW: The Joy of JavaScript: What Is This Thing Called JavaScript? 15 0732 CH11 4/24/01 11:23 AM Page 286 As the Web’s population grew, more and more users were clicking more and more Send buttons. More and more web servers were thus spending more and more time processing scripts in between serving web pages. Mean- while, the user’s browser sat there, doing nothing. A tool was needed to transfer the process from the server to the client (the user’s computer). Enter JavaScript. JavaScript, Yesterday and Today In 1995, the company formerly known as Netscape Communications Cor- poration introduced a client-side programming language designed to transfer the burden of interactive processing from the web server to the end-user’s browser. Unlike other programming languages (such as Java or C), this new language was built into the browser. It even understood HTML. Netscape called its new client-side scripting language LiveScript, but soon changed the name to JavaScript to capitalize on the growing excitement about Sun’s Java language. To this day, as a result of their similar names, many beginning web designers (and users) confuse Java with JavaScript. The relationship between the two is mainly one of marketing. Netscape quickly promised to release JavaScript as a web standard so that other browsers could use it too. But for competitive reasons, the company initially held back on its pledge. Old browsers like Mosaic could not use JavaScript at all. Neither could Microsoft’s newly unveiled Internet Explorer. To offset Netscape’s advantage, Microsoft’s browser engineers developed a JavaScript-like language called JScript. Web design quickly became a cir- cle of Hell, as serious developers were forced to work with these similar but incompatible technologies. Freelancers and small firms, lacking deep resources, often chose to support only one technology. That one was nearly always JavaScript, especially in the beginning when Internet Explorer enjoyed only a tiny share of the market. Thus JavaScript functioned as a sort of standard before it really was one. 287 Taking Your Talent to the Web 15 0732 CH11 4/24/01 11:23 AM Page 287 Around the Millennium, JavaScript finally became an official web standard, available to all. As reported in Chapter 2, “Designing for the Medium,” the European Computer Manufacturers Association (ECMA) supervised the standardization of JavaScript, renaming it in the process. The universal web scripting language is now officially known as ECMAScript or ECMA-262, though no one we know calls it anything but JavaScript. (Our Scandana- vian friends pronounce it “Ya-va-script,” which we find incredibly endear- ing. That has nothing to do with any of this, but it does lend this chapter a certain international flair.) The point is that JavaScript/ECMAScript is a standard that works in all cur- rent browsers, though there are still some subtle incompatibilities being worked out between the latest versions of Netscape, Internet Explorer, Opera, and other browsers. Meanwhile, the DOM has been standardized by W3C. Prior to that, JavaScript had its own ever-changing DOM in Netscape, and Microsoft had its own DOM as well. As all browsers finalize complete support for these standards, web design- ers and developers are being empowered to create sophisticated interac- tivity that works for everyone. Conversely, as browsers lag in their DOM and ECMAScript support, web designers and developers are stuck programming alternate versions of every site function, often going so far as to develop alternate versions of the sites themselves. Now that we’ve concluded our mini-history lesson and you’ve finished your nap, let’s move on to the good stuff. JAVASCRIPT,UNHH! W HAT IS IT GOOD FOR? Absolutely lots of things. Through this web-friendly programming lan- guage, designers and developers can: ■ Replace cryptic status bar URLs (“http://www.doglovers.com/ poodles.html”) with text messages (“Learn about poodles”), a some- what controversial practice, for reasons we’ll discuss in a moment. ■ Create the ever-popular image rollover effect discussed in Chapter 9, “Visual Tools.” 288 HOW: The Joy of JavaScript: JavaScript, Unhh! What Is It Good For? 15 0732 CH11 4/24/01 11:23 AM Page 288 ■ Compensate for browser incompatibilities. ■ Open new, precisely sized “pop-up” windows, with or without various bits of browser chrome. ■ Test for the presence or absence of Flash, QuickTime, or other plug- ins (more about plug-ins in Chapter 12, “Beyond Text/Pictures”). ■ Rotate content and images depending on the time of day, the num- ber of times the user has viewed a certain page, or simply at random. ■ Enable the client to inject 50 links on a page without cluttering that page at all. ■ Provide alternative means of navigating the site. ■ “Remember” that a user has visited the site before, sparing her the pain of reentering personal data or passwords. This is accomplished by means of cookies (Netscape terminology for little bits of text that reside on the end-user’s hard drive and can be recognized by JavaScript on subsequent visits to the site). ■ Cause images or text boxes to scroll horizontally or vertically, another controversial and often annoying practice. ■ Verify the credibility of email addresses entered on “customer feed- back” forms. JavaScript won’t tell you if a person is using her email address or someone else’s, but it will tell you if the address is well formed or not. (If malformed, it is probably a nonworking address.) ■ Control complex frames—of less importance than it used to be, as frames are gradually being phased out. Similarly, JavaScript can pro- tect sites from a third party’s poorly crafted frames. ■ Create nested navigational menus that reveal secondary and tertiary levels in response to cursor movements—a wonderful idea because it enables visitors to navigate directly to the information they seek, but problematic because not all browsers fully support a standard means of doing this. ■ …and much more. Add the W3C DOM to what JavaScript does already and you can change that phrase to “much, much, much more.” 289 Taking Your Talent to the Web 15 0732 CH11 4/24/01 11:23 AM Page 289 We know what you’re saying. “Sounds great, but I’m, like, an artist. Do I really have to learn this stuff?” SOUNDS GREAT, BUT I’MANARTIST. DO I R EALLY HAVE TO LEARN THIS STUFF? The politically correct answer is, yes you do, because adding interactivity to your clients’ sites is part of what makes you a web designer. The gentle answer is, learning JavaScript is an iterative process: You can begin by cut- ting and pasting and gradually come to understand what you’re working with. The Richard Nixon Memorial answer is, not at first, and maybe never. Not at first and maybe never is an answer because many working web designers get by for years doing nothing more than cutting and pasting other people’s scripts. By the way, we’re not talking about stealing code. Many developers freely offer their scripts in return for an acknowledge- ment in the source code, and some don’t even ask for that (http:// javascripts.earthweb.com/). Likewise, many other web designers get along by using WYSIWYG editors such as Macromedia Dreamweaver and Adobe Golive and image editors such as Macromedia Fireworks—programs that can create many standard JavaScript functions for you. Some respected web designers have never programmed a line of JavaScript code; they let Dreamweaver do it. But most web designers do learn at least the basics of JavaScript because, sooner or later, they run into problems they cannot solve without it. A prob- lem like this can occur: A certain page does not display properly in Netscape 4. The solution would be to create an alternate page that does work in Netscape 4 and use JavaScript to send Netscape 4 users to that alternate page. For nearly every design problem like this, there is a simple JavaScript solution. The other problem with cutting and pasting (or relying on a WYSIWYG edi- tor) is that browsers change, web standards evolve, and cut-and-paste scripts as well as WYSIWYG editors tend to lag behind. 290 HOW: The Joy of JavaScript: Sounds Great, but I’m an Artist 15 0732 CH11 4/24/01 11:23 AM Page 290 [...]... 11:23 AM Page 291 Taking Your Talent to the Web Hopefully, Microsoft, Netscape, and Opera will soon patch the holes in their ECMAScript and DOM support, and Macromedia and Adobe will vastly improve their support for these standards in Dreamweaver and Golive, respectively If both things happen, you might be able to spend the rest of your life banging out advanced JavaScript functions with no clue as to. .. charming way of referring to the status bar at the bottom of the web page (The status bar is the part of the browser that usually displays the bare-naked URL, generally at the lower left.) Without getting too hairy, JavaScript gives each object in its document model an address based on the object’s position within the document’s hierarchy, moving from the top level of the hierarchy down to the details:... fashions for men 15 0732 CH11 4/24/01 11:23 AM Page 295 Taking Your Talent to the Web Many visitors might find this message far more useful than a bare-naked URL And your client would certainly dig it Fortunately, it is easy to accommodate these visitors and your client with JavaScript Text rollovers are one of the easiest effects you can possibly create First, let’s look at a typical HTML link: Explore FASHION... Thau’s JavaScript tutorial at Webmonkey (http:// hotwired.lycos.com/webmonkey/javascript/tutorials/tutorial1.html) Give yourself at least two days to go through all the exercises in this five-part tutorial The JavaScript School at www.w3schools.com/js/ is another great place to learn Classic and recent JavaScript/DOM articles may be found at http://www.javascript.about.com/ We highly recommend that you... can do that, and then we’ll move on to examine how JavaScript helps web designers solve typical problems that arise in the development of any professional site EDUCATING RITA ABOUT JAVASCRIPT We’ve called JavaScript a relatively “easy -to- learn” programming language, but it is a programming language, and teaching it is beyond the scope of this book In some ways, teaching it is beyond the scope of fat... in the status bar message Thanks to your cleverness, even before the visitor hovers over a link, the status bar at the bottom of the browser will proudly proclaim, “Welcome to FASHION MAVEN.” Can you feel your client’s love? We can You have now carried your client’s brand down to the level of the status bar Had you not done this, the status bar would read “Internet Zone” or something equally meaningless... like a web designer Then you’ll go back and fix your syntax Speaking of which… The fine print Because single quotation marks are used to denote the beginning and ending of text messages, what do you do if your text includes an apostrophe? After all, in HTML, an apostrophe is exactly the same as a single quotation mark What you do is “escape” the single quotation mark by inserting a backslash character... tells the browser to treat the quotation mark as a quotation mark, not a string terminator (meaning, not the end of a JavaScript statement) Forgotten backslashes have caused many a web designer her share of sleepless nights Return of the son of fine print Yep, one more tip Forget the semicolon, and you will create JavaScript errors in many browsers, which unfortunately will not show up in many others That’s... 11:23 AM Page 299 Taking Your Talent to the Web Notice that it is possible to create dynamic web effects in web pages that live on your desktop—without requiring a web server Hooray for JavaScript! A Cautionary Note Like everything you can do on the Web, modifying the default status bar message involves trade-offs and thus requires thought Browsers use defaultStatus to communicate with users, letting them... exactly the same syntax to replace the onMouseOver message with a default status bar message When the user places the mouse pointer over the link, he’ll read “FASHION MAVEN fashions for men.” When he releases the mouse, our insistent client will replace that link-specific brand message with a general one: “Welcome to FASHION MAVEN.” This general message will remain in the visitor’s status bar until . as a sort of standard before it really was one. 287 Taking Your Talent to the Web 15 0732 CH11 4/24/01 11:23 AM Page 287 Around the Millennium, JavaScript finally became an official web standard, available. JavaScript’s charming way of referring to the status bar at the bottom of the web page. (The status bar is the part of the browser that usually displays the bare-naked URL, gen- erally at the lower left.). standard, available to all. As reported in Chapter 2, “Designing for the Medium,” the European Computer Manufacturers Association (ECMA) supervised the standardization of JavaScript, renaming it in the
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