The Node Beginner BookWord文档下载推荐.docx

The Node Beginner BookWord文档下载推荐.docx

《The Node Beginner BookWord文档下载推荐.docx》由会员分享，可在线阅读，更多相关《The Node Beginner BookWord文档下载推荐.docx（38页珍藏版）》请在冰豆网上搜索。

Which,ofcourse,isnotexactlyworld-changing,butwewillgosomeextramilesandnotonlycreatethecodethatis"

justenough"

tomaketheseusecasespossible,butcreateasimple,yetcompleteframeworktocleanlyseparatethedifferentaspectsofourapplication.YouwillseewhatImeaninaminute.

WewillstartwithlookingathowJavaScriptdevelopmentinNode.jsisdifferentfromJavaScriptdevelopmentinabrowser.

Next,wewillstaywiththegoodoldtraditionofwritinga"

application,whichisamostbasicNode.jsapplicationthat"

does"

something.

Then,wewilldiscusswhatkindof"

real"

applicationwewanttobuild,dissectthedifferentpartswhichneedtobeimplementedtoassemblethisapplication,andstartworkingoneachofthesepartsstep-by-step.

Aspromised,alongthewaywewilllearnaboutsomeofthemoreadvancedconceptsofJavaScript,howtomakeuseofthem,andlookatwhyitmakessensetousetheseconceptsinsteadofthoseweknowfromotherprogramminglanguages.

Thesourcecodeofthefinishedapplicationisavailablethrough 

theNodeBeginnerBookGithubrepository.

Tableofcontents

∙About

oStatus

oIntendedaudience

oStructureofthisdocument

∙JavaScriptandNode.js

oJavaScriptandYou

oAwordofwarning

oServer-sideJavaScript

o"

∙AfullblownwebapplicationwithNode.js

oTheusecases

oTheapplicationstack

∙Buildingtheapplicationstack

oAbasicHTTPserver

oAnalyzingourHTTPserver

oPassingfunctionsaround

oHowfunctionpassingmakesourHTTPserverwork

oEvent-drivencallbacks

oHowourserverhandlesrequests

oFindingaplaceforourservermodule

oWhat'

sneededto"

route"

requests?

oExecutioninthekingdomofverbs

oRoutingtorealrequesthandlers

oMakingtherequesthandlersrespond

▪Howtonotdoit

▪Blockingandnon-blocking

▪Respondingrequesthandlerswithnon-blockingoperations

oServingsomethinguseful

▪HandlingPOSTrequests

▪Handlingfileuploads

oConclusionandoutlook

JavaScriptandNode.js

JavaScriptandYou

Beforewetalkaboutallthetechnicalstuff,let'

stakeamomentandtalkaboutyouandyourrelationshipwithJavaScript.Thischapterisheretoallowyoutoestimateifreadingthisdocumentanyfurthermakessenseforyou.

Ifyouarelikeme,youstartedwithHTML"

development"

longago,bywritingHTMLdocuments.YoucamealongthisfunnythingcalledJavaScript,butyouonlyuseditinaverybasicway,addinginteractivitytoyourwebpageseverynowandthen.

Whatyoureallywantedwas"

therealthing"

youwantedtoknowhowtobuildcomplexwebsites-youlearnedaprogramminglanguagelikePHP,Ruby,Java,andstartedwriting"

backend"

code.

Nevertheless,youkeptaneyeonJavaScript,yousawthatwiththeintroductionofjQuery,Prototypeandthelikes,thingsgotmoreadvancedinJavaScriptland,andthatthislanguagereallywasaboutmorethan 

window.open（）.

However,thiswasallstillfrontendstuff,andalthoughitwasnicetohavejQueryatyourdisposalwheneveryoufeltlikespicingupawebpage,attheendofthedayyouwere,atbest,aJavaScript 

user,butnotaJavaScript 

developer.

AndthencameNode.js.JavaScriptontheserver,howcoolisthat?

Youdecidedthatit'

sabouttimetocheckouttheold,newJavaScript.Butwait,writingNode.jsapplicationsistheonething;

understandingwhytheyneedtobewrittenthewaytheyarewrittenmeans-understandingJavaScript.Andthistimeforreal.

Hereistheproblem:

BecauseJavaScriptreallylivestwo,maybeeventhreelives（thefunnylittleDHMTLhelperfromthemid-90'

s,themoreseriousfrontendstufflikejQueryandthelikes,andnowserver-side）,it'

snotthateasytofindinformationthathelpsyoutolearnJavaScriptthe"

right"

way,inordertowriteNode.jsapplicationsinafashionthatmakesyoufeelyouarenotjustusingJavaScript,youareactuallydevelopingit.

Becausethat'

sthecatch:

youalreadyareanexperienceddeveloper,youdon'

twanttolearnanewtechniquebyjusthackingaroundandmis-usingit;

youwanttobesurethatyouareapproachingitfromtherightangle.

Thereis,ofcourse,excellentdocumentationoutthere.Butdocumentationalonesometimesisn'

tenough.Whatisneededisguidance.

Mygoalistoprovideaguideforyou.

Awordofwarning

TherearesomereallyexcellentJavaScriptpeopleoutthere.I'

mnotoneofthem.

I'

mreallyjusttheguyItalkedaboutinthepreviousparagraph.Iknowathingortwoaboutdevelopingbackendwebapplications,butI'

mstillnewto"

JavaScriptandstillnewtoNode.js.IlearnedsomeofthemoreadvancedaspectsofJavaScriptjustrecently.I'

mnotexperienced.

Whichiswhythisisno"

fromnovicetoexpert"

book.It'

smorelike"

fromnovicetoadvancednovice"

.

IfIdon'

tfail,thenthiswillbethekindofdocumentIwishIhadwhenstartingwithNode.js.

Server-sideJavaScript

ThefirstincarnationsofJavaScriptlivedinbrowsers.Butthisisjustthecontext.Itdefineswhatyoucandowiththelanguage,butitdoesn'

tsaymuchaboutwhatthelanguageitselfcando.JavaScriptisa"

complete"

language:

youcanuseitinmanycontextsandachieveeverythingwithityoucanachievewithanyother"

language.

Node.jsreallyisjustanothercontext:

itallowsyoutorunJavaScriptcodeinthebackend,outsideabrowser.

InordertoexecutetheJavaScriptyouintendtoruninthebackend,itneedstobeinterpretedand,well,executed.ThisiswhatNode.jsdoes,bymakinguseofGoogle'

sV8VM,thesameruntimeenvironmentforJavaScriptthatGoogleChromeuses.

Plus,Node.jsshipswithalotofusefulmodules,soyoudon'

thavetowriteeverythingfromscratch,likeforexamplesomethingthatoutputsastringontheconsole.

Thus,Node.jsisreallytwothings:

aruntimeenvironmentandalibrary.

Inordertomakeuseofthese,youneedtoinstallNode.js.Insteadofrepeatingtheprocesshere,Ikindlyaskyoutovisit 

theofficialinstallationinstructions.Pleasecomebackonceyouareupandrunning.

"

Ok,let'

sjustjumpinthecoldwaterandwriteourfirstNode.jsapplication:

"

Openyourfavoriteeditorandcreateafilecalled 

helloworld.js.Wewantittowrite"

toSTDOUT,andhereisthecodeneededtodothat:

console.log（"

）;

Savethefile,andexecuteitthroughNode.js:

nodehelloworld.js

Thisshouldoutput 

HelloWorld 

onyourterminal.

Ok,thisstuffisboring,right?

Let'

swritesomerealstuff.

AfullblownwebapplicationwithNode.js

Theusecases

Let'

skeepitsimple,butrealistic:

∙Theusershouldbeabletouseourapplicationwithawebbrowser

∙Theusershouldseeawelcomepagewhenrequestinghttp:

//domain/startwhichdisplaysafileuploadform

∙Bychoosinganimagefiletouploadandsubmittingtheform,thisimageshouldthenbeuploadedtohttp:

//domain/upload,whereitisdisplayedoncetheuploadisfinished

Fairenough.Now,youcouldachievethisgoalbygooglingandhackingtogethersomething.Butthat'

snotwhatwewanttodohere.

Furthermore,wedon'

twanttowriteonlythemostbasiccodetoachievethegoal,howeverelegantandcorrectthiscodemightbe.WewillintentionallyaddmoreabstractionthannecessaryinordertogetafeelingforbuildingmorecomplexNode.jsapplications.

Theapplicationstack

sdissectourapplication.Whichpartsneedtobeimplementedinordertofulfilltheusecases?

∙Wewanttoservewebpages,thereforeweneedan 

HTTPserver

∙Ourserverwillneedtoanswerdifferentlytorequests,dependingonwhichURLtherequestwasaskingfor,thusweneedsomekindof 

router 

inordertomaprequeststorequesthandlers

∙Tofulfilltherequeststhatarrivedattheserverandhavebeenroutedusingtherouter,weneedactual 

requesthandlers

∙TherouterprobablyshouldalsotreatanyincomingPOSTdataandgiveittotherequesthandlersinaconvenientform,thusweneed 

requestdatahandling

∙WenotonlywanttohandlerequestsforURLs,wealsowanttodisplaycontentwhentheseURLsarerequested,whichmeansweneedsomekindof 

viewlogic 

therequesthandlerscanuseinordertosendcontenttotheuser'

sbrowser

∙Lastbutnotleast,theuserwillbeabletouploadimages,sowearegoingtoneedsomekindof 

uploadhandling 

whichtakescareofthedetails

sthinkamomentabouthowwewouldbuildthi