Intro | Head Rush Ajax (Head First)

You won't believe the things I learned from reading Head Rush Ajax. I just finished learning how to...

In this section, we answer the burning question: "So, why DID they put that in an Ajax book?"

Who is this book for ?

If you can answer "yes" to all of these:

Do you know HTML, some CSS, and some JavaScript? (You don't need to be a guru.)
Do you want to learn, understand, and remember Ajax, with a goal of developing more responsive web applications?
Do you prefer stimulating dinner party conversation to dry, dull, academic lectures?

this book is for you.

Who should probably back away from this book?

If you can answer "yes" to any one of these:

Are you completely new to HTML or CSS or JavaScript? (You don't need to be advanced, but you should definitely have some experience. If not, go get a copy of Head First HTML and CSS, today, and then come back and get this book.)
Are you a kick-butt Ajax developer looking for a reference book?
Are you afraid to try something different? Would you rather have a root canal than mix stripes with plaid? Do you believe that a technical book can't be serious if browsers are anthropomorphized?

this book is not for you.

[Note from marketing: this book is for anyone who can afford it.]

We know what you're thinking.

"How can this be a serious programming book?"

"What's with all the graphics?"

"Can I actually learn it this way?"

"Do I smell pizza?"

And we know what your brain is thinking

Your brain thinks THIS is important.

Your brain craves novelty. It's always searching, scanning, waiting for something unusual. It was built that way, and it helps you stay alive.

So what does your brain do with all the routine, ordinary, normal things you encounter? Everything it can to stop them from interfering with the brain's real jobrecording things that matter. It doesn't bother saving the boring things; they never make it past the "this is obviously not important" filter.

How does your brain know what's important? Suppose you're out for a day hike and a tiger jumps in front of you; what happens inside your head and body?

Neurons fire. Emotions crank up. Chemicals surge.

And that's how your brain knows...

This must be important! Don't forget it!

Great. Only 637 more dull, dry, boring pages.

Your brain thinks THIS isn't worth saving.

But imagine you're at home, or in a library. It's a safe, warm, tiger-free zone. You're studying. Getting ready for an exam. Or trying to learn some tough technical topic your boss thinks will take a week, ten days at the most.

Just one problem. Your brain's trying to do you a big favor. It's trying to make sure that this obviously non-important content doesn't clutter up scarce resources. Resources that are better spent storing the really big things. Like tigers. Like the danger of fire. Like how you should never again snowboard in shorts.

And there's no simple way to tell your brain, "Hey brain, thank you very much, but no matter how dull this book is, and how little I'm registering on the emotional Richter scale right now, I really do want you to keep this stuff around." .

We think of a "Head Rush" reader as a learner.

So what does it take to learn something? First, you have to get it, then make sure you don't forget it. It's not about pushing facts into your head. Based on the latest research in cognitive science, neurobiology, and educational psychology, learning takes a lot more than text on a page. We know what turns your brain on.

Some of the Head Rush learning principles:

It's actually the web browser that is "running" all your JavaScript code.

The getBoardsSold() function calls the createRequest() function.

Make it visual. Images are far more memorable than words alone, and make learning much more effective (up to 89% improvement in recall and transfer studies). It also makes things more understandable. Put the words within or near the graphics they relate to, rather than on the bottom or on another page, and learners will be up to twice as likely to solve problems related to the content.

Use a conversational and personalized style. In recent studies, students performed up to 40% better on post-learning tests if the content spoke directly to the reader, using a first-person, conversational style rather than taking a formal tone. Tell stories instead of lecturing. Use casual language. Don't take yourself too seriously. Which would you pay more attention to: a stimulating dinner party companion, or a lecture?

Get the learner to think more deeply. In other words, unless you actively flex your neurons, nothing much happens in your head. A reader has to be motivated, engaged, curious, and inspired to solve problems, draw conclusions, and generate new knowledge. And for that, you need challenges, exercises, thought-provoking questions, and activities that involve both sides of the brain, and multiple senses.

Be the Architect

Getand keepthe reader's attention. We've all had the "I really want to learn this but I can't stay awake past page one" experience. Your brain pays attention to things that are out of the ordinary, interesting, strange, eye-catching, unexpected. Learning a new, tough, technical topic doesn't have to be boring. Your brain will learn much more quickly if it's not.

Touch their emotions. We now know that your ability to remember something is largely dependent on its emotional content. You remember what you care about. You remember when you feel something. No, we're not talking heart-wrenching stories about a boy and his dog. We're talking emotions like surprise, curiosity, fun, "what the...?", and the feeling of "I Rule!" that comes when you solve a puzzle, learn something everybody else thinks is hard, or realize you know something that "more-technical-than-thou" Bob from engineering doesn't.

Metacognition: thinking about thinking

If you really want to learn, and you want to learn more quickly and more deeply, pay attention to how you pay attention. Think about how you think. Learn how you learn.

I wonder how I can trick my brain into remembering this stuff...

Most of us did not take courses on metacognition or learning theory when we were growing up. We were expected to learn, but rarely taught to learn.

But we assume that if you're holding this book, you want to learn Ajax. And you probably don't want to spend a lot of time. And since you're going to develop applications, you need to remember what you read. And for that, you've got to understand it. To get the most from this book, or any book or learning experience, take responsibility for your brain. Your brain on this content.

The trick is to get your brain to see the new material you're learning as Really Important. Crucial to your well-being. As important as a tiger. Otherwise, you're in for a constant battle, with your brain doing its best to keep the new content from sticking.

So just how DO you get your brain to treat Ajax like it's a hungry tiger?

There's the slow, tedious way, or the faster, more effective way. The slow way is about sheer repetition. You obviously know that you are able to learn and remember even the dullest of topics if you keep pounding the same thing into your brain. With enough repetition, your brain says, "This doesn't feel important to him, but he keeps looking at the same thing over and over and over, so I suppose it must be."

The faster way is to do anything that increases brain activity, especially different types of brain activity. The things on the previous page are a big part of the solution, and they're all things that have been proven to help your brain work in your favor. For example, studies show that putting words within the pictures they describe (as opposed to somewhere else in the page, like a caption or in the body text) causes your brain to try to makes sense of how the words and picture relate, and this causes more neurons to fire. More neurons firing = more chances for your brain to get that this is something worth paying attention to, and possibly recording.

A conversational style helps because people tend to pay more attention when they perceive that they're in a conversation, since they're expected to follow along and hold up their end. The amazing thing is, your brain doesn't necessarily care that the "conversation" is between you and a book! On the other hand, if the writing style is formal and dry, your brain perceives it the same way you experience being lectured to while sitting in a roomful of passive attendees. No need to stay awake.

But pictures and conversational style are just the beginning.

Here's what WE did:

We used pictures, because your brain is tuned for visuals, not text. As far as your brain's concerned, a picture really is worth 1,024 words. And when text and pictures work together, we embedded the text in the pictures because your brain works more effectively when the text is within the thing the text refers to, as opposed to in a caption or buried in the text somewhere.

We used repetition, saying the same thing in different ways and with different media types, and multiple senses, to increase the chance that the content gets coded into more than one area of your brain.

We used concepts and pictures in unexpected ways because your brain is tuned for novelty, and we used pictures and ideas with at least some emotional content, because your brain is tuned to pay attention to the biochemistry of emotions. That which causes you to feel something is more likely to be remembered, even if that feeling is nothing more than a little humor, surprise, or interest.

We used a personalized, conversational style, because your brain is tuned to pay more attention when it believes you're in a conversation than if it thinks you're passively listening to a presentation. Your brain does this even when you're reading.

Speak Up!

We included more than 40 activities, because your brain is tuned to learn and remember more when you do things than when you read about things. And we made the exercises challenging-yetdo- able, because that's what most people prefer.

We used multiple learning styles, because you might prefer step-by-step procedures, while someone else wants to understand the big picture first, and someone else just wants to see a code example. But regardless of your own learning preference, everyone benefits from seeing the same content represented in multiple ways.

We include content for both sides of your brain, because the more of your brain you engage, the more likely you are to learn and remember, and the longer you can stay focused. Since working one side of the brain often means giving the other side a chance to rest, you can be more productive at learning for a longer period of time.

60 Second Review

And we included stories and exercises that present more than one point of view, because your brain is tuned to learn more deeply when it's forced to make evaluations and judgments.

Espresso Talk

We included challenges, with exercises, and by asking questions that don't always have a straight answer, because your brain is tuned to learn and remember when it has to work at something. Think about ityou can't get your body in shape just by watching people at the gym. But we did our best to make sure that when you're working hard, it's on the right things. That you're not spending one extra dendrite processing a hard-to-understand example, or parsing difficult, jargon-laden, or overly terse text.

We used people. In stories, examples, pictures, etc., because, well, because you're a person. And your brain pays more attention to people than it does to things.

We used an 80/20 approach. We assume that if you're going for a Ph.D in Ajax, this won't be your only book. So we don't talk about everything. Just the stuff you'll actually need.

Here's what YOU can do to bend your brain into submission

So, we did our part. The rest is up to you. These tips are a starting point; listen to your brain and figure out what works for you and what doesn't. Try new things.

Cut this out and stick it on your refridgerator.

Slow down. The more you understand, the less you have to memorize.
Don't just read. Stop and think. When the book asks you a question, don't just skip to the answer. Imagine that someone really is asking the question. The more deeply you force your brain to think, the better chance you have of learning and remembering.
Do the exercises. Write your own notes.
We put them in, but if we did them for you, that would be like having someone else do your workouts for you. And don't just look at the exercises. Use a pencil. There's plenty of evidence that physical activity while learning can increase the learning.
Read the "Frequently Asked Questions."
That means all of them. They're not optional side-barsthey're part of the core content! Don't skip them.
Don't do all your reading in one place.
Stand-up, stretch, move around, change chairs, change rooms. It'll help your brain (and body) feel something, and keep your learning from being too connected to a particular place. Remember, you won't be taking the exam in your bedroom.
Make this the last thing you read before bed. Or at least the last challenging thing.
Part of the learning (especially the transfer to long-term memory) happens after you put the book down. Your brain needs time on its own, to do more processing. If you put in something new during that processing-time, some of what you just learned will be lost.
Drink water. Lots of it.
Your brain works best in a nice bath of fluid. Dehydration (which can happen before you ever feel thirsty) decreases cognitive function. Beer, or something stronger, is called for when you pass the exam.
Talk about it. Out loud.
Speaking activates a different part of the brain. If you're trying to understand something, or increase your chance of remembering it later, say it out loud. Better still, try to explain it out loud to someone else. You'll learn more quickly, and you might uncover ideas you didn't know were there when you were reading about it.
Listen to your brain.
Pay attention to whether your brain is getting overloaded. If you find yourself starting to skim the surface or forget what you just read, it's time for a break. Once you go past a certain point, you won't learn faster by trying to shove more in, and you might even hurt the process.
Feel something!
Your brain needs to know that this matters. Get involved with the stories. Make up your own captions for the photos. Groaning over a bad joke is still better than feeling nothing at all.

Read Me

This is a learning experience, not a reference book. We deliberately stripped out everything that might get in the way of learning whatever it is we're working on at that point in the book. And the first time through, you need to begin at the beginning, because the book makes assumptions about what you've already seen and learned.

We assume you are familiar with HTML and CSS.

It would take an entire book to teach you HTML and CSS (in fact, that's exactly what it took: Head First HTML with CSS & XHTML). We chose to focus this book on Ajax programming, rather than rehash lots of markup and style that you could learn about in other places.

We assume you've at least seen JavaScript code before.

It would take an entire book to teach you... oh, wait, we've already said that. Seriously, JavaScript is a lot more than a simple scripting language, and we aren't going to cover all the ways you can use JavaScript in this book. You'll learn about all the ways that JavaScript is related to Ajax programming, and learn how to use JavaScript extensively to add interaction to your web pages and make requests to a server.

However, if you've never written a line of JavaScript, aren't at all familiar with functions or curly braces, or have never programmed in any language before, you might want to pick up a good JavaScript book and browse through it. If you want to plow into this book, feel freebut we will be moving fairly quickly over the basics.

We don't cover server-side programming in this book.

It's now common to find server-side programs written in Java, PHP, Ruby, Python, Perl, Ruby on Rails, C#, and a whole lot more. Ajax programming works with all of these languages, and we have tried to represent several of them in this book's examples.

To keep you focused on learning Ajax, though, we do not spend much time explaining the server-side programs used; we'll show you the server-side code with some notes, but that's as far as we go. We believe that your Ajax applications can be written to work with any kind of server-side program; we also believe that you're smart enough to apply the lessons learned from an example that uses PHP to one that uses Ruby on Rails or a Java servlet.

We encourage you to use more than one browser with this book.

As much as it sucks, different web browsers handle your HTML, your CSS, and your JavaScript in completely different ways. If you want to be a complete Ajax programmer, you should always test your asynchronous applications on lots of modern browsers. All the examples in this book were tested on recent versions of Firefox, Opera, Safari, Internet Explorer, and Mozilla. If you find problems, though, let us know... we promise it's an accident.

We often use tag names for element names.

Rather than saying "the a element," or "the 'a' element," we use a tag name, like "the <a> element." While this may not be technically correct (because <a> is an opening tag, not a full blown element), it does make the text more readable.

The activities are NOT optional.

The exercises and activities are not add-ons; they're part of the core content of the book. Some of them are to help with memory, some are for understanding, and some will help you apply what you've learned. Don't skip the exercises.

The examples are as lean as possible.

Our readers tell us that it's frustrating to wade through 200 lines of an example looking for the two lines they need to understand. Most examples in this book are shown within the smallest possible context, so that the part you're trying to learn is clear and simple. Don't expect all of the examples to be robust, or even completethey are written specifically for learning, and aren't always fully functional.

We've placed all the example files on the Web so you can download them. You'll find them at http://www.headfirstlabs.com/books/hrajax/.

The redundancy is intentional and important.

One distinct difference in a Head First book is that we want you to really get it. And we want you to finish the book remembering what you've learned. Most reference books don't have retention and recall as a goal, but this book is about learning, so you'll see many of the concepts come up more than once.

The 'Brain Power' exercises don't have answers.

For some of them, there is no right answer, and for others, part of the learning experience of the Brain Power activities is for you to decide if and when your answers are right. In some of the Brain Power exercises you will find hints to point you in the right direction.

Tech Reviewers

I'm so phenomenally lucky to have a killer team of reviewers. Johannes de Jong probably thinks that he didn't do much, and of course he'd be very, very wrong. Johannes started the review, kept it running, and made jokes about whiskey at all the right times. Pauline McNamara manages to be in every Head First (and now Head Rush) book, probably because she's such an uber-reviewer. She co-managed the review, and was always technically correct and yet still "cool." Go figure! Valentin Crettaz found every grammatical mistake I've ever made, and even kept my diagrams technically accurate. What a combination. Kristin Stromberg came to the fray late, and just devoured the chapters. Her feedback was right on point, and really helped make the book more fun, engaging, and enjoyable. You should thank her... seriously! Andrew Monkouse made some great Ajaxspecific comments that really kept me on my Ajax toes. Nice work, Andrew! And a special thanks, and shout out, to Bear Bibeault. Bear, I know life got in the way, but I appreciate your involvement all the same, man!

I hope you like this book, guysthis book is yours as much as it is mine.

Johannes de Jong

Valentin Crettaz

Andrew Monkhouse

Kristin Stromberg

Pauline McNamara

Eric and Beth Freeman

It seems like these books end up being as much about friendships as about writing and teaching. If it weren't for Beth Freeman and Eric Freeman, my life wouldn't be as rich as it is. They brought me into the Head First family, trusted me, and taught me (about strange faux meat as well as ferries and crazy stories). Beth wrote Chapter 3, and Eric worked on the cover and a lot of the new Head Rush elements. Guys, more than your help, I really value your friendship. See ya soon.

Beth Freeman

Eric Freeman

And there's a lot nore...*

At O'Reilly:

Mike Hendrickson has managed to be the guy who kept this project going, through every conceivable obstable. Mike, this book wouldn't have happened without you. You've seen me through some ragged times, and I'm sure there are more coming. Good to know you'll be there for me when things get tense.

Sometimes you know that a chapter is almost right, but there's some nagging detail that is missing. Those are the times when I turn to my editor, Mike Loukides; he always sees to know just what's missing. This is our fourth book together, and we're already planning the fifth and sixth.

Mike Loukides

My heartfelt thanks go out to my team of O'Reilly co-conspirators: Greg Corrin led the way on marketing, and in particular kicked butt the last week of writing. Ellie Volkhausen did that first cover design so long ago, and Mike Kohnke and Karen Montgomery took the cover to another level for Head Rush. Thanks to Colleen Gorman for doing another amazing copyedityou just keeping doing these Head First books, and I love that. Sue Willing, Ron Bilodeau, and Marlowe Shaeffer took care of making sure the printer was happy, and that's no small task.

It's really no accident that the name "O'Reilly" is on the cover. Tim O'Reilly took a chance, and keeps taking chances, on this series. Tim, you'll never know how honored I am to be a part of this series.

Greg Corrin

Kathy Sierra and Bert Bates:

You simple can't do one of these books without spending serious time talking to Kathy Sierra and Bert Bates, the geniuses who created the Head First series. Bert and Kathy both did hard time the last week of this project, staying up late chatting with me on how to make each page just that little bit better. The book wouldn't be the same without you guys, and your friendship is worth even more than that!

Kathy Sierra

Bert Bates

* The large number of acknowledgments is because we're testing the theory that everyone mentioned in a book acknowledgment will buy at least one copy, probably more, what with relatives and everything. If you'd like to be in the acknowledgment of our next book, and you have a large family, write to us.