If you can answer âyesâ to all of these:
Do you have access to a computer with a modern web browser and a text editor?
Do you want to learn, understand and remember how to program with JavaScript using the best techniques and the most recent standards?
Do you prefer stimulating dinner party conversation to dry, dull, academic lectures?
this book is for you.
If you can answer âyesâ to any one of these:
Are you completely new to web development?
Are HTML and CSS foreign concepts to you? If so, youâll probably want to start with Head First HTML and CSS to understand how to put web pages together before tackling JavaScript.
Are you a kick-butt web 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 canât be serious if JavaScript objects are anthropomorphized?
this book is not for you.
âHow can this be a serious book?â
âWhatâs with all the graphics?â
âCan I actually learn it this way?â
Your brain craves novelty. Itâs always searching, scanning, waiting for something unusual. It was built that way, and it helps you stay alive.
Today, youâre less likely to be a tiger snack. But your brainâs still looking. You just never know.
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 brainâs real jobârecording things that matter. It doesnât bother saving the boring things; they never make it past the âthis is obviously not importantâ filter.
How does your brain know whatâs important? Suppose youâre 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 thatâs how your brain knows...
This must be important! Donât forget it!
But imagine youâre at home, or in a library. Itâs a safe, warm, tiger-free zone. Youâre 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 brainâs trying to do you a big favor. Itâs trying to make sure that this obviously non-important content doesnât 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 thereâs no simple way to tell your brain, âHey brain, thank you very much, but no matter how dull this book is, and how little Iâm registering on the emotional Richter scale right now, I really do want you to keep this stuff around.â
We think of a âHead Firstâ reader as a learner.
So what does it take to learn something? First, you have to get it, then make sure you donât forget it. Itâs 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 First learning principles:
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. Donât 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 and thought-provoking questions, and activities that involve both sides of the brain and multiple senses.
Getâand keepâthe readerâs attention. Weâve all had the âI really want to learn this but I canât stay awake past page oneâ experience. Your brain pays attention to things that are out of the ordinary, interesting, strange, eye-catching, unexpected. Learning a new, tough, technical topic doesnât have to be boring. Your brain will learn much more quickly if itâs 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, weâre not talking heart-wrenching stories about a boy and his dog. Weâre talking emotions like surprise, curiosity, fun, âwhat the...?â, and the feeling of âI Rule!â that comes when you solve a puzzle, learn something everybody else thinks is hard, or realize you know something that âIâm more technical than thouâ Bob from engineering doesnât.
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.
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 how to learn.
But we assume that if youâre holding this book, you really want to learn how to create JavaScript programs. And you probably donât want to spend a lot of time. And you want to remember what you read, and be able to apply it. And for that, youâve 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 youâre learning as Really Important. Crucial to your well-being. As important as a tiger. Otherwise, youâre in for a constant battle, with your brain doing its best to keep the new content from sticking.
So how DO you get your brain to think JavaScript is as important as a tiger?
Thereâs 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 on the same thing. With enough repetition, your brain says, âThis doesnât feel important to him, but he keeps looking at the same thing over and over and over, so I suppose it must be.â
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 theyâre 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 make 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 theyâre in a conversation, since theyâre expected to follow along and hold up their end. The amazing thing is, your brain doesnât necessarily care that the âconversationâ 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.
We used pictures, because your brain is tuned for visuals, not text. As far as your brainâs concerned, a picture really is worth 1024 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 redundancy, 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 youâre in a conversation than if it thinks youâre passively listening to a presentation. Your brain does this even when youâre reading.
We included more than 100 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-yet-do-able, because thatâs 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, while 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.
And we included stories and exercises that present more than one point of view, because your brain is tuned to learn more deeply when itâs forced to make evaluations and judgements.
We included challenges, with exercises, and by asking questions that donât always have a straight answer, because your brain is tuned to learn and remember when it has to work at something. Think about itâyou canât get your body in shape just by watching people at the gym. But we did our best to make sure that when youâre working hard, itâs on the right things. That youâre 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, youâre 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 youâre going to be a kick-butt JavaScript developer, this wonât be your only book. So we donât talk about everything. Just the stuff youâll actually need.
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 doesnât. Try new things.
Slow down. The more you understand, the less you have to memorize.
Donât just read. Stop and think. When the book asks you a question, donât 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 donât just look at the exercises. Use a pencil. Thereâs plenty of evidence that physical activity while learning can increase the learning.
Read the âThere are No Dumb Questionsâ
That means all of them. Theyâre not optional sidebarsâtheyâre part of the core content! Donât skip them.
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.
Talk about it. Out loud.
Speaking activates a different part of the brain. If youâre 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. Youâll learn more quickly, and you might uncover ideas you hadnât known 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, itâs time for a break. Once you go past a certain point, you wonât 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.
Create something!
Apply this to something new youâre designing, or rework an older project. Just do something to get some experience beyond the exercises and activities in this book. All you need is a pencil and a problem to solve... a problem that might benefit from using JavaScript.
Get Sleep.
Youâve got to create a lot of new brain connections to learn to program. Sleep often; it helps.
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 weâre 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 youâve already seen and learned.
We teach the GOOD parts of JavaScript, and warn you about the BAD parts.
JavaScript is a programming language that didnât come up through the ivy leagues with plenty of time for academic peer review. JavaScript was thrown out into the world out of necessity and grew up in the early browser neighborhood. So, be warned: JavaScript has some great parts and some not so great parts. But, overall, JavaScript is brilliant, if you use it intelligently.
In this book, we teach you to use the great parts to best advantage, and weâll point out the bad parts, and advise you to drive around them.
We donât exhaustively cover every single aspect of the language.
Thereâs a lot you can learn about JavaScript. This book is not a reference book; itâs a learning book, so it doesnât cover everything there is to know about JavaScript. Our goal is to teach you the fundamentals of using JavaScript so that you can pick up any old reference book and do whatever you want with JavaScript.
This book does teach you JavaScript in the browser.
The browser is not only the most common environment that JavaScript runs in, itâs also the most convenient (everyone has a computer with a text editor and a browser, and thatâs all you need to get started with JavaScript). Running JavaScript in the browser also means you get instant gratification: you can write code and all you have to do is reload your web page to see what it does.
This book advocates well-structured and readable code based on best practices.
You want to write code that you and other people can read and understand, code that will still work in next yearâs browsers. You want to write code in the most straight-forward way so you can get the job done and get on to better things. In this book weâre going to teach you to write clear, well-organized code that anticipates change from the get-go. Code you can be proud of, code youâll want to frame and put on the wall (just take it down before you bring your date over).
We encourage you to use more than one browser with this book.
We teach you to write JavaScript that is based on standards, but youâre still likely to encounter minor differences in the way web browsers interpret JavaScript. While weâll do our best to ensure all the code in the book works in all modern browsers, and even show you a couple of tricks to make sure your code is supported by those browsers, we encourage you to pick at least two browsers and test your JavaScript using them. This will give you experience in seeing the differences among browsers and in creating JavaScript code that works well in a variety of browsers with consistent results.
Programming is serious business. Youâre going to have to work, sometimes hard.
If youâve already had some programming experience, then you know what weâre talking about. If youâre coming straight from Head First HTML and CSS, then youâre going to find writing code is a little, well, different. Programming requires a different way of thinking. Programming is logical, at times very abstract, and requires you to think in an algorithmic way. But no worries; weâre going to do all that in a brain-friendly way. Just take it a bit at a time, make sure youâre well nourished and get plenty of sleep. That way, these new programming concepts will really sink in.
The activities are NOT optional.
The exercises and activities in this book are not add-ons; theyâre 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 youâve learned. Donât skip the exercises. The crossword puzzles are the only things you donât have to do, but theyâre good for giving your brain a chance to think about the words in a different context.
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 youâve learned. Most reference books donât have retention and recall as a goal, but this book is about learning, so youâll see some of the same concepts come up more than once.
The examples are as lean as possible.
Our readers tell us that itâs 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 youâre trying to learn is clear and simple. Donât expect all of the examples to be robust, or even completeâthey are written specifically for learning, and arenât always fully-functional.
Weâve placed all the example files on the Web so you can download them. Youâll find them at http://wickedlysmart.com/hfjs.
The âBrain Powerâ exercises donât usually 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.
We often give you only the code, not the markup.
After we get past the first chapter or two, we often give you just the JavaScript code and assume youâll wrap it in a nice HTML wrapper. Hereâs a simple HTML page you can use with most of the code in this book, and if we want you to use other HTML, weâll tell you:
Get the code examples, help and discussion
Youâll find everything you need for this book online at http://wickedlysmart.com/hfjs, including code sample files and additional support material including videos.
Thank you to our amazing review team
This book has been more carefully reviewed than any of our previous books. In fact, over 270 people joined our WickedlySmart Insiders program and participated in reading and critiquing this book in real time as we wrote it. This worked better than we ever imagined and was instrumental in shaping every aspect of Head First JavaScript Programming. Our heartfelt thanks to everyone who participated; the book is so much better because of you.
The amazing technical reviewers pictured above provided feedback above and beyond, and each made significant contributions to this book. The following reviewers also made contributions across different aspects of the book: Galina N. Orlova, J. Patrick Kelley, Claus-Peter Kahl, Rob Cleary, Rebeca Dunn-Krahn, Olaf Schoenrich, Jim Cupec, Matthew M. Hanrahan, Russell Alleen-Willems, Christine J. Wilson, Louis-Philippe Breton, Timo Glaser, Charmaine Gray, Lee Beckham, Michael Murphy, Dave Young, Don Smallidge, Alan Rusyak, Eric R. Liscinsky, Brent Fazekas, Sue Starr, Eric (Orange Pants) Johnson, Jesse Palmer, Manabu Kawakami, Alan McIvor, Alex Kelley, Yvonne Bichsel Truhon, Austin Throop, Tim Williams, J. Albert Bowden II, Rod Shelton, Nancy DeHaven Hall, Sue McGee, Francisco Debs, Miriam Berkland, Christine H Grecco, Elhadji Barry, Athanasios Valsamakis, Peter Casey, Dustin Wollam and Robb Kerley.
Acknowledgments[1]
Weâre also extremely grateful to our esteemed technical reviewer David Powers. The truth is we donât write books without David anymore, heâs just saved our butts too many times. Itâs getting a little like Elton and Bernie; weâre starting to ask ourselves if we actually could write a book without him. David helps us forces us to make the book more sound and technically accurate, and his second career as a standup comic really comes in handy when weâre tuning the more humorous parts of the book. Thank you once again Davidâyouâre the ultimate professional and we sleep better at night knowing weâve passed your technical muster.
At OâReilly:
A huge, massive thanks to our editor, Meghan Blanchette, who cleared the path for this book, removed every obstacle to its completion, waited patiently and sacrificed family time to get it done. Sheâs also the person who keeps us sane in our relationship with OâReilly (and keeps OâReilly sane in their relationship with us). We love you and canât wait to collaborate with you again!
And another big shoutout to our Chief Editor Emeritus, Mike Hendrickson, who spearheaded this book from the very beginning. Thanks again Mike; none of our books would have happened without you. Youâve been our champion for well over a decade and we love you for it!
Also At OâReilly:
Our sincerest thanks as well to the whole OâReilly team: Melanie Yarbrough, Bob Pfahler and Dan Fauxsmith, who wrangled the book into shape; to Ed Stephenson, Huguette Barriere, and Leslie Crandell who led the way on marketing and we appreciate their out-of-the-box approach. Thanks to Ellie Volkhausen, Randy Comer and Karen Montgomery for their inspired cover design that continues to serve us well. Thank you, as always, to Rachel Monaghan for her hardcore copyedit (and for keeping it all fun), and to Bert Bates for his valuable feedback.
[1] The large number of acknowledgments is because weâre testing the theory that everyone mentioned in a book acknowledgment will buy at least one copy, probably more, what with relatives and everything. If youâd like to be in the acknowledgment of our next book, and you have a large family, write to us.
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