JavaScript for Web Developers.pdf

ProfessionalJavaScriptforWebDevelopers ProfessionalJavaScriptmforWebDevelopers Nicholasc.zakas ( WILEY WileyPublishingInc ProfessionalJavaScriptforWebDevelopers Copyrighto2005byWileypublishingInc.Allrightsreserved PublishedbyWileyPublishing,Inc,Indianapolis,Indiana PublishedsimultaneouslyinCanada Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedinanyform orbyanymeans,electronic,mechanical,photocopying,recording,scanning,orotherwise,exceptas permittedunderSection107or108ofthe1976UnitedStatesCopyrightAct,withouteithertheprior writtenpermissionofthePublisher,orauthorizationthroughpaymentoftheappropriateper-copyfee totheCopyrightClearanceCenter,Inc,222RosewoodDrive,Danvers,MAO1923,(978)750-8400,fax (978)646-8700RequeststothePublisherforpermissionshouldbeaddressedtotheLegalDepartment, WileyPublishing,Inc,10475CrosspointBlvd.Indianapolis,IN46256,(317)572-3447,fax(317) 572-4355,oronlineatwww.wiley.com/go/permissions LIMITOFLIABILITY/DISCLAIMEROFWARRANTY:THEPUBLISHERANDTHEAUTHOR MAKENOREPRESENTATIONSORWARRANTIESWITHRESPECTTOTHEACCURACYOR COMPLETENESSOFTHECONTENTSOFTHISWORKANDSPECIFICALLYDISCLAIMALL WARRANTIES,INCLUDINGWITHOUTLIMITATIONWARRANTIESOFFITNESSFORAPARTIC ULARPURPOSE.NOWARRANTYMAYBECREATEDOREXTENDEDBYSALESORPROMO- TIONALMATERIALS.THEADVICEANDSTRATEGIESCONTAINEDHEREINMAYNOTBE SUITABLEFOREVERYSITUATION.THISWORKISSOLDWITHTHEUNDERSTANDINGTHAT THEPUBLISHERISNOTENGAGEDINRENDERINGLEGAL,ACCOUNTING,OROTHERPRO FESSIONALSERVICES.IFPROFESSIONALASSISTANCEISREQUIRED,THESERVICESOFA COMPETENTPROFESSIONALPERSONSHOULDBESOUGHT.NEITHERTHEPUBLISHERNOT THEAUTHORSHALLBELIABLEFORDAMAGESARISINGHEREFROM.THEFACTTHATAN ORGANIZATIONORWEBSITEISREFERREDTOINTHISWORKASACITATIONAND/ORA POTENTIALSOURCEOFFURTHERINFORMATIONDOESNOTMEANTHATTHEAUTHOROR THEPUBLISHERENDORSESTHEINFORMATIONTHEORGANIZATIONORWEBSITEMAY PROVIDEORRECOMMENDATIONSITMAYMAKE.FURTHER,READERSSHOULDBEAWARE THATINTERNETWEBSITESLISTEDINTHISWORKMAYHAVECHANGEDORDISAPPEARED BETWEENWHENTHISWORKWASWRITTENANDWHENITISREAD ForgeneralinformationonourotherproductsandservicespleasecontactourCustomerCareDepart mentwithintheUnitedStatesat(800)762-2974,outsidetheUnitedStatesat317)572-3993orfax(317) 572-4002 Trademarks:Wiley,theWileyPublishinglogo,Wrox,theWroxlogo,andProgrammertoProgrammer trademarkofSunMicrosystems,IncintheUnitedStatesandothercountries.Allothertrademarks? aretrademarksorregisteredtrademarksofJohnWileySons,Incand/oritsaffiliates.JavaScript thepropertyoftheirrespectiveowners.WileyPublishing,Inc.isnotassociatedwithanyproductor vendormentionedinthisbook Wileyalsopublishesitsbooksinavarietyofelectronicformats.Somecontentthatappearsinprint maynotbeavailableinelectronicbooks LibraryofCongressCataloging-in-PublicationDataisavailablefromthepublisher ISBN-13:978-0-7645-7908-0 ISBN-10:0-7645-7908-8 PrintedintheUnitedStatesofamerica 10987654321 Abouttheauthor NicholasC.zakasisauserinterfacedesignerforWebapplications,specializinginclient-sidetechnolo giessuchasJavaScript,HTML,andCSS.NicholascurrentlyworksasSeniorSoftwareEngineer,Design Engineering,atMatrixOne,Inc.locatedinWestford,Massachusetts,USA NicholashasaB.S.inComputerSciencefrommerrimackCollege,wherehelearnedtraditionalpro- gramminginCandC++.Duringcollege,hebeganinvestigatingtheWorldwideWebandhTmLinhis sparetime,eventuallyteachinghimselfenoughtobehiredasWebmasterofasmallsoftwarecompany namedRadnet,IncinWakefield,Massachusetts,USA.ItwastherethatNicholasbeganlearning JavaScriptandworkingonWebapplications NicholascanbereachedthroughhisWebsitehttp://www.nczonline.net/ Credits VicePresidentandExecutiveGroupPublisher: DevelopmentEditor: Richardwadley SharonNash VicePresidentandpublisher: Seniorproductioneditor JosephBLikert Angelasmith AcquisitionsEditor Technicaleditor: JimMintel Jean-LucDavid,Wiley-DreamtechIndiaPvtLtd EditorialManager TextDesignComposition: MarybethWakefield Wileycompositionservices Acknowledgments Ittakesmorethanjustonepersontowriteabookofthisnature,despitethesinglenameonthefront cover.Withoutthehelpofnumerousindividualsthisbookwouldnothavebeenpossible Firstareforemost,thankstoeveryoneatWileyPublishing,especiallyJimMinatelandSharonNash,for providingalltheguidanceandsupportthatanewauthorneeds ThankstoallthosewhoofferedtheirideasonwhatagoodJavaScriptbookshouldinclude:Keith Ciociola,KenFearnley,JohnRajan,andDouglasSwatski Aspecialthankstoeveryonewhoreviewedthesubjectmatteraheadoftime:ErikArvidssonbradley Baumann,GuilhermeBlanco,DouglasCrockford,Jean-LucDavid,EmilAEklund,BrettFielder,Jeremy McPeak,andMichaSchopman.Allyourinputwasexcellentandmadeforamuchbetterbook ThankstoDrs.EdandfrancesBernardforkeepingmeintip-tophealthduringthewritingofthisbook andthepastfewyears Last,butcertainlynotleast,thankstomyfamily,mom,dad,andGregandmyextremelyunderstanding girlfriend,Emily.Yourloveandsupporthelpedtakemefromtheproposaltothefinalpublishedcopy.