A Smarter Way to Learn JavaScript
Contents
1. file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript Let s get back to the original examples the facts I asked you to memorize These facts can change and if they do the terms my name and my nationality will refer to new values I could go to court and change my name to Ace Then my name is no longer Mark If I want you to address me correctly I ll have to tell you that my name is now Ace After I tell you that you ll know that my name doesn t refer to the value it used to refer to Mark but refers to a new value Ace If I transfer my nationality to U K my nationality is no longer U S It s U K If I want you to know my nationality I ll have to tell you that it is now U K After I tell you that you ll know that my nationality doesn t refer to the original value U S but now refers to a new value J avaScript variables can also change If I code var name Mark name refers to Mark Then I come along and code the line name Ace Before I coded the new line if I asked J avaScript to print name it printed Mark But that was then Now if I ask JavaScript to print name it prints Ace A variable can have any number of values but only one at a time You may be wondering why in the statement above that assigns Ace to name the keyword var is missing It s because the variable was declared earlier in the original stateme2. Forget it Extra help for the rough spots Can t afford it Hundreds of examples Better delete some But no such limitation applies to an ebook What do an extra hundred digital pages cost Usually nothing When a book is published traditionally it may take up to a year for the manuscript to get into print This means there isn t time for extensive testing on the target audience or for the revisions that testing would inevitably suggest And once the book is in print it s a big expensive deal to issue revised editions Publishers put it off as long as possible Reader feedback usually doesn t lead to improvements for years An ebook can go from manuscript to book in a day leaving lots of time for testing and revision After it s published new editions with improvements based on reader feedback can come out as often as the author likes at no cost With all this going for them is there any doubt that all the best instructional books are going to be ebooks And would anyone deny that the most helpful thing an author can do for file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript you in addition to publishing a good book electronically is to take on the whole teaching job not just part of it by adding interactivity to help you with memorization practice and correction Here then is how I propose to use current technology to help you learn J avaScript in h
3. second statement it doesn t add 23 7 to total 30 It does something that might surprise you I ll tell you about this in a subsequent chapter For now know that a number enclosed by quotation marks is not a number but a string and J avaScript can t do addition on it Note that any particular variable name can be the name of a number variable or string variable From J avaScript s point of view there s nothing in a name that denotes one kind of variable or another In fact a variable can start out as one type of variable then become another type of variable Did you notice what s new in 1 var originalNumber 23 2 var newNumber originalNumber 7 The statement assigns to the variable newNumber the result of a mathematical operation The result of this operation of course is a number value The example mixes a variable and a literal number in a math expression But you could also use nothing but numbers or nothing but variables It s all the same to J avaScript I ve told you that you can t begin a variable name with a number The statement var istPresident Washington file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM
4. 1 03 47 AM A Smarter Way to Learn JavaScript then ask J avaScript to print floogle J avaScript prints Mark Within limits you can name variables anything you want and J avaScript won t care var lessonAuthor Mark var WhoK ingHisOwnN Mark var x Mark J avaScript s blindness to meaning notwithstanding when it comes to variable names you ll want to give your variables meaningful names because it ll help you and other coders understand your code Again the syntactic difference between variables and text strings is that variables are never enclosed in quotes and text strings are always enclosed in quotes It s always var lastName Smith var cityOfOrigin New Orleans var aussieGreeting g Day If it s an alphabet letter or word and it isn t enclosed in quotes and it isn t a keyword that has special meaning for JavaScript like alert it s a variable If it s some characters enclosed in quotes it s a text string If you haven t noticed let me point out the spaces between the variable and the equal sign and between the equal sign and the value var nickname Bub These spaces are a style choice rather than a legal requirement But I ll ask you to include them in your code throughout the practice exercises file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript In the last chapter you learned to write al
5. A Smarter Way to Learn JavaScript A Smarter Way to Learn JavaScript The new approach that uses technology to cut your effort in half Strin Finding a character at a location chapter of this book ASmarterWayToLearn com 1 Read a 10 minute 2 Code for 20 minutes at to get each concept to own the skill It s free Mark Myers file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript practice and correction When the computer gets into the act you ll learn twice as fast with half the effort It s a smarter way to learn J avaScript It s a smarter way to learn anything And as long as we re embracing new technology why not use all the tech we can get our hands on to optimize the book Old technology i e the paper book has severe limitations from an instructional point of view New technology i e the ebook is the way to go for many reasons Here are a few Color is a marvelous information tool That s why they use it for traffic lights But printing color on paper multiplies the cost Thanks to killer setup charges printing this single word color in a print on demand book adds thirty dollars to the retail price So color is usually out or else the book is priced as a luxury item With an ebook color is free Paper itself is expensive so there usually isn t room to do everything the author would like to do A full discussion of fine points
6. If I ask you whether my nationality is the same as yours I won t have to ask Is your nationality the same as U S I ll ask Is your nationality the same as my nationality You ll remember that when I say my nationality I m referring to U S and you ll compare your nationality to U S even though I haven t said U S explicitly In these examples the terms my name and my nationality work the same way J avaScript variables do My name is a term that refers to a particular value Mark In the same way a variable is a word that refers to a particular value A variable is created when you write var for variable followed by the name that you choose to give it It takes on a particular value when you assign the value to it This is a J avaScript statement that creates the variable name and assigns the value Mark to it var name Mark Now the variable name refers to the text string Mark Note that it was my choice to call it name I could have called it myName xyz lol or something else It s up to me how to name my variables within limits With the string Mark assigned to the variable name my J avaScript code doesn t have to specify Mark again Whenever J avaScript encounters name J avaScript knows that it s a variable that refers to Mark For example if you ask JavaScript to print name it remembers the value that name refers to and prints Mark The value that a variable refers to can change
7. a text string like a ZIP code that it handles as text But then since it s not enclosed in quotes how does J avaScript know it s not a variable Well because a number or any combination of characters starting with a number can t be used as a variable name If it s a number J avaScript rejects it as a variable So it must be a number If you enclose a number in quotation marks it s a string JavaScript can t do addition on it It can do addition only on numbers not enclosed in quotes Now look at this code 1 var originalNum 23 2 var newNum originalNum 7 In the second statement in the code above J avaScript substitutes the number 23 when it encounters the variable originalNum It adds 7 to 23 And it assigns the result 30 to the variable newNum JavaScript can also handle an expression made up of nothing but variables For example 1 var originalNum 23 2 var numToBeAdded 7 3 var newNum originalNum numToBeAdded A variable can be used in calculating its own new value file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript 1 var originalNum 90 2 originalNum originalNum 10 If you enclose a number in quotation marks and add 7 1 var originalNum 23 2 var newNum originalNum 7 it won t work because J avaScript can t sum a string and a number J avaScript interprets 23 as a word not a number In the
8. alf the time with half the effort Cognitive portion control Testing showed me that when they re doing hard core learning even strong minded people get tired faster than I would have expected You may be able to read a novel for two hours at a stretch but when you re studying something new and complicated it s a whole different ballgame My testing revealed that studying new material for about ten minutes is the limit before most learners start to fade But here s the good news Even when you ve entered the fatigue zone after ten minutes of studying you ve still got the mental wherewithal to practice for up to thirty minutes Practice that s designed correctly takes less effort than studying yet teaches you more Reading a little and practicing a lot is the fastest way to learn 500 coding examples that cover every aspect of what you re learning Examples make concepts easy to grasp and focus your attention on the key material covered in each chapter Color cues embedded in the code help you commit rules to memory Did I go overboard and put in more examples that you need Well if things get too easy for you just skip some them Tested on naive users The book includes many rounds of revisions based on feedback from programming beginners It includes extra help discussions to clarify concepts that proved to be stumbling blocks during testing Among the testers my technophobe wife who discovered that with good instruction she could
9. code and was surprised to find that she enjoyed it For that matter I got a file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript few surprises myself Some things that are simple to me turned out not to be not so simple to some readers Rewriting ensued Free interactive coding exercises paired with each chapter 1 750 of them in all They re the feature that testers say helps them the most No surprise there According to the New York Times psychologists have shown that taking a test say writing down all you can remember from a studied prose passage can deepen the memory of that passage better than further study I would venture that this goes double when you re learning to code After reading each chapter go online and practice everything you learned Each chapter ends with a link to its accompanying online exercises Find an index of all the exercises at http www ASmarterWayToLearn com js Live coding experience In scripting the best reward is seeing your code run flawlessly Most practice sessions include live coding exercises that let you see your scripts execute in the browser How to use this book This isn t a book quite like any you ve ever owned before so a brief user manual might be helpful Study practice then rest If you re intent on mastering the fundamentals of JavaScript as opposed to just getting a feel for the language w
10. creating the algorithms that check your work would be for me a project of driverless car proportions Besides learning to write code with fastidious precision helps you learn to pay close attention to details a fundamental requirement for coding in any language Subscribe temporarily to my formatting biases Current code formatting is like seventeenth century spelling Everyone does it his own way There are no universally accepted standards But the algorithms that check your work when you do the interactive exercises need standards They can t grant you the latitude that a human teacher could because let s face it they aren t that bright So I ve had to settle on certain conventions All of the conventions I teach are embraced by a large segment of the coding community so you ll be in good company But that doesn t mean you ll be married to my formatting biases forever When you begin coding projects you ll soon develop your own opinions or join an organization that has a stylebook Until then I ll ask you to make your code look like my code Email me with any problems or questions The book and exercises have been tested on many learners but haven t been tested on you If you hit a snag if you re just curious about something or if I ve found some way to give you fits email me at mark ASmarterWayToLearn com I ll be happy to hear from you I ll reply promptly And with file Cl KindleGen a smarter way to learn javascript pdf h
11. ert Thanks for your input When the code executes a message box displays saying Thanks for your input But what if you wrote these two statements instead 1 var thanx Thanks for your input 2 alert thanx Instead of placing a text string inside the parentheses of the alert statement the code above assigns the text string to a variable Then it places the variable not the string inside the parentheses Because J avaScript always substitutes the value for the variable J avaScript displays not the variable name thanx but the text to which it refers Thanks for your input That same alert Thanks for your input displays Find the interactive coding exercises for this chapter at http www ASmarterWayToLearn com js 2 html 3 Variables for Numbers A string isn t the only thing you can assign to a variable You can also assign a number var weight 150 Having coded the statement above whenever you write weight in your code J avaScript knows you mean 150 You can file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript use this variable in math calculations If you ask J avaScript to add 25 to weight weight 25 avaScript remembering that weight refers to 150 will come up with the sum 175 Unlike a string a number is not enclosed in quotes That s how J avaScript knows it s a number that it can do math on and not
12. ical put my tablet into horizontal mode to proof this book So please starting with Chapter 1 do yourself a favor and rotate your tablet reader or phone to give yourself a longer line of text It ll help prevent the unpleasant code jumble mentioned above Do the coding exercises on a physical keyboard A mobile device can be ideal for reading but it s no way to code Very very few Web developers would attempt to do their work on a phone The same thing goes for learning to code Theoretically most of the interactive exercises could be done on a mobile device But the idea seems so perverse that I ve disabled online practice on tablets readers and phones Read the book on your mobile device if you like But practice on your laptop If you have an authority problem try to get over it When you start doing the exercises you ll find that I can be file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript a pain about insisting that you get every little detail right For example if you indent a line one space instead of two spaces the program monitoring your work will tell you the code isn t correct even though it would still run perfectly Do I insist on having everything just so because I m a control freak No it s because I have to place a limit on harmless maverick behavior in order to automate the exercises If I were to grant you as much freedom as you might like
13. nt that assigned Mark to it Remember var is the keyword that file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript creates a variable the keyword that declares it Once a variable has been declared you don t have to declare it again You can just assign the new value to it You can declare a variable in one statement leaving it undefined Then you can assign a value to it in a later statement without declaring it again var nationality nationality U S In the example above the assignment statement follows the declaration statement immediately But any amount of code can separate the two statements as long as the declaration statement comes first In fact there s no law that says you have to ever define a variable that you ve declared J avaScript variable names have no inherent meaning to J avaScript In English words have meaning You can t use just any word to communicate I can say My name is Mark but if I want to be understood I can t say My floogle is Mark That s nonsense But with variables JavaScript is blind to semantics You can use just any word as long as it doesn t break the rules of variable naming From J avaScript s point of view var floogle Mark 1S Just as good as var name Mark If you write var floogle Mark file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 1
14. ork with this book and the online exercises in a 15 to 30 minute session then take a break Study a chapter for 5 to 10 minutes Immediately go online at http www ASmarterWayToLearn com js and code for 10 to 20 minutes practicing the lesson until you ve coded file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript everything correctly Then go for a walk Use the largest most colorful screen available This book can be read on small phone screens and monochrome readers but you ll be happier if things appear in color on a larger screen I use color as an important teaching tool so if you re reading in black and white you re sacrificing some of the extra teaching value of a full color ebook Colored elements do show up as a lighter shade on some black and white screens and on those devices the effect isn t entirely lost but full color is better As for reading on a larger screen the book includes more than 2 000 lines of example code Small screens break long lines of code into awkward arbitrary segments jumbling the formatting While still decipherable the code becomes harder to read If you don t have a mobile device that s ideal for this book consider installing the free Kindle reading app on your laptop If you re reading on a mobile device go horizontal For some reason I resist doing this on my iPad unless I m watching a video But even I Vern Vert
15. tive sentence with a period In scripting a careful coder ends every statement with a semicolon Sometimes complex paragraph like statements end with a curly bracket instead of a semicolon That s something I ll cover in a later chapter A semicolon isn t always necessary but it s easier to end every statement with a semicolon rather than stop to figure out whether you need one In this training I ll ask you to end every statement that doesn t end with a curly bracket with a semicolon e Some coders write window alert instead of simply alert This is a highly formal but perfectly correct way to write it Most coders prefer the short form We ll stick to the short form in this training e In the example above some coders would use single rather than double quotation marks This is legal as long as it s a matching pair But in a case like this I ll ask you to use double quotation marks Find the interactive coding exercises for this chapter at http www ASmarterWayToLearn com js Lhtml 2 Variables for Strings Please memorize the following facts e My name is Mark e My nationality is U S file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript Now that you ve memorized my name and nationality I won t have to repeat them literally again If I say to you You probably know other people who have my name you ll know I m referring to Mark
16. tml 12 14 2013 11 03 47 AM your help I ll probably learn something that improves the next edition 1 Alerts An alert is a box that pops up to give the user a message Here s code for an alert that displays the message Thanks for your input alert Thanks for your input alert is a keyword that is a word that has special meaning for J avaScript It means Display in an alert box the message that follows Note that alert isn t capitalized If you capitalize it the script will stop The parentheses are a special requirement of J avaScript one that you ll soon get used to You ll be typing parens over and over again in all kinds of J avaScript statements In coding the quoted text Thanks for your input is called a text string or simply a string The name makes sense it s a string of characters enclosed in quotes Outside the coding world we d just call it a quotation Note that the opening parenthesis is jammed up against the keyword and the opening quotation mark is hugging the opening parenthesis Since JavaScript ignores spaces except in text strings you could write alert Thanks for your input But I want you to know the style conventions of file Cl KindleGen a smarter way to learn javascript pdf html 12 14 2013 11 03 47 AM A Smarter Way to Learn JavaScript JavaScript so I ll ask you to always omit spaces before and after parentheses In English a careful writer ends every declara
Download Pdf Manuals
Related Search