book

Learning JavaScript, 3rd Edition

by Ethan Brown

February 2016

Beginner

348 pages

8h 40m

English

O'Reilly Media, Inc.

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A Brief History of JavaScriptES6Who This Book Is ForWhat This Book Is NotConventions Used in This BookO’Reilly SafariHow to Contact UsAcknowledgments
Where to StartThe ToolsA Comment on CommentsGetting StartedThe JavaScript ConsoleDrawing Graphics PrimitivesAutomating Repetitive TasksHandling User InputHello, World
PrerequisitesYour Project RootWhat Are You Trying to Do?Node ApplicationsInstalling NodeRunning JavaScript Programs with NodePackage Management: npmWeb ApplicationsLintingConclusion
Variables and ConstantsVariables or Constants: Which to Use?Identifier NamesLiteralsPrimitive Types and ObjectsNumbersStringsEscapingSpecial CharactersTemplate StringsMultiline StringsNumbers as StringsBooleansSymbolsnull and undefinedObjectsNumber, String, and Boolean ObjectsArraysTrailing Commas in Objects and ArraysDatesRegular ExpressionsMaps and SetsData Type ConversionConverting to NumbersConverting to StringConverting to BooleanConclusion
A Control Flow Primerwhile LoopsBlock StatementsWhitespaceHelper Functionsif…else Statementdo…while Loopfor Loopif StatementPutting It All TogetherControl Flow Statements in JavaScriptControl Flow ExceptionsChaining if...else StatementsMetasyntaxAdditional for Loop Patternsswitch Statementsfor...in loopfor...of loopUseful Control Flow PatternsUsing continue to Reduce Conditional NestingUsing break or return to Avoid Unnecessary ComputationUsing Value of Index After Loop CompletionUsing Descending Indexes When Modifying ListsConclusion
OperatorsArithmetic OperatorsOperator PrecedenceComparison OperatorsComparing NumbersString ConcatenationLogical OperatorsTruthy and Falsy ValuesAND, OR, and NOTShort-Circuit EvaluationLogical Operators with Nonboolean OperandsConditional OperatorComma OperatorGrouping OperatorBitwise Operatorstypeof Operatorvoid OperatorAssignment OperatorsDestructuring AssignmentObject and Array OperatorsExpressions in Template StringsExpressions and Control Flow PatternsConverting if...else Statements to Conditional ExpressionsConverting if Statements to Short-Circuited Logical OR ExpressionsConclusion
Return ValuesCalling Versus ReferencingFunction ArgumentsDo Arguments Make the Function?Destructuring ArgumentsDefault ArgumentsFunctions as Properties of ObjectsThe this KeywordFunction Expressions and Anonymous FunctionsArrow Notationcall, apply, and bindConclusion
Scope Versus ExistenceLexical Versus Dynamic ScopingGlobal ScopeBlock ScopeVariable MaskingFunctions, Closures, and Lexical ScopeImmediately Invoked Function ExpressionsFunction Scope and HoistingFunction HoistingThe Temporal Dead ZoneStrict ModeConclusion
A Review of ArraysArray Content ManipulationAdding or Removing Single Elements at the Beginning or EndAdding Multiple Elements at the EndGetting a SubarrayAdding or Removing Elements at Any PositionCutting and Replacing Within an ArrayFilling an Array with a Specific ValueReversing and Sorting ArraysArray SearchingThe Fundamental Array Operations: map and filterArray Magic: reduceArray Methods and Deleted or Never-Defined ElementsString JoiningConclusion
Property Enumerationfor...inObject.keysObject-Oriented ProgrammingClass and Instance CreationDynamic PropertiesClasses Are FunctionsThe PrototypeStatic MethodsInheritancePolymorphismEnumerating Object Properties, RevisitedString RepresentationMultiple Inheritance, Mixins, and InterfacesConclusion

MapsWeak MapsSetsWeak SetsBreaking the Object Habit
The Error ObjectException Handling with try and catchThrowing ErrorsException Handling and the Call Stacktry...catch...finallyLet Exceptions Be Exceptional
The Iteration ProtocolGeneratorsyield Expressions and Two-Way CommunicationGenerators and returnConclusion
Functions as SubroutinesFunctions as Subroutines That Return a ValueFunctions as…FunctionsSo What?Functions Are ObjectsIIFEs and Asynchronous CodeFunction VariablesFunctions in an ArrayPass a Function into a FunctionReturn a Function from a FunctionRecursionConclusion
The AnalogyCallbackssetInterval and clearIntervalScope and Asynchronous ExecutionError-First CallbacksCallback HellPromisesCreating PromisesUsing PromisesEventsPromise ChainingPreventing Unsettled PromisesGeneratorsOne Step Forward and Two Steps Back?Don’t Write Your Own Generator RunnerException Handling in Generator RunnersConclusion
Dates, Time Zones, Timestamps, and the Unix EpochConstructing Date ObjectsMoment.jsA Practical Approach to Dates in JavaScriptConstructing DatesConstructing Dates on the ServerConstructing Dates in the BrowserTransmitting DatesDisplaying DatesDate ComponentsComparing DatesDate ArithmeticUser-Friendly Relative DatesConclusion
Formatting NumbersFixed DecimalsExponential NotationFixed PrecisionDifferent BasesAdvanced Number FormattingConstantsAlgebraic FunctionsExponentiationLogarithmic FunctionsMiscellaneousPseudorandom Number GenerationTrigonometric FunctionsHyperbolic Functions
Substring Matching and ReplacingConstructing Regular ExpressionsSearching with Regular ExpressionsReplacing with Regular ExpressionsInput ConsumptionAlternationMatching HTMLCharacter SetsNamed Character SetsRepetitionThe Period Metacharacter and EscapingA True WildcardGroupingLazy Matches, Greedy MatchesBackreferencesReplacing GroupsFunction ReplacementsAnchoringWord Boundary MatchingLookaheadsConstructing Regexes DynamicallyConclusion
The Document Object ModelSome Tree TerminologyDOM “Get” MethodsQuerying DOM ElementsManipulating DOM ElementsCreating New DOM ElementsStyling ElementsData AttributesEventsEvent Capturing and BubblingEvent CategoriesAjaxConclusion
Node FundamentalsModulesCore Modules, File Modules, and npm ModulesCustomizing Modules with Function ModulesFilesystem AccessProcessOperating SystemChild ProcessesStreamsWeb ServersConclusion
Accessor Properties: Getters and SettersObject Property AttributesProtecting Objects: Freezing, Sealing, and Preventing ExtensionProxiesConclusion
Online DocumentationPeriodicalsBlogs and TutorialsStack OverflowContributing to Open Source ProjectsConclusion
Installing GitUsing Git

Content preview from Learning JavaScript, 3rd Edition

Chapter 19. Node

Up until 2009, JavaScript was almost exclusively a browser scripting language.¹ In 2009, frustrated by the state of server-side options, a Joyent developer named Ryan Dahl created Node. Node’s adoption was meteoric, and it even achieved success in the notoriously slow-to-adopt enterprise markets.

For those who liked JavaScript as a language, Node made it possible to use the language for tasks traditionally relegated to other languages. For web developers, the appeal is stronger than just the choice of language. Being able to write JavaScript on the server means a consistent language choice—no mental context-switching, a reduced reliance on specialists, and (perhaps most importantly) the ability to run the same code on the server and the client.

While Node was introduced to enable web application development, its jump to the server inadvertently enabled other nontraditional uses, such as desktop application development and system scripting. In a sense, Node allowed JavaScript to grow up and join the party.

Node Fundamentals

If you can write JavaScript, you can write Node applications. That’s not to say that you can simply take any browser-based JavaScript program and run it on Node: browser-based JavaScript uses APIs that are specific to the browser. In particular, in Node, there is no DOM (which makes sense: there’s no HTML). Likewise, there are APIs that are specific to Node that don’t exist in the browser. Some, like operating system and filesystem support, ...