WEB_Core JavaScript Guide

servernavigatorTCP/IPHTMLublishingcommunitysystemsecurityChaURLmerchantsystemWorldWideWebPersonalCoreJavaScriptGuideOctober30,1998Version1.4wwSSLProxyIStoreIntermailMozillaInternetencryptionHTMLJavaScriptcomp.syscertificatedirectoryserver(Netscape)anditslicensorsretainallownershiprightstothesoftwareprogramsofferedbyNetscape(referredtohereinasSoftware)andrelateddocumentation.UseoftheSoftwareandrelateddocumentationisgovernedbythelicenseagreementaccompanyingtheSoftwareandapplicablecopyrightlaw.Yourrighttocopythisdocumentationislimitedbycopyrightlaw.Makingunauthorizedcopies,adaptations,orcompilationworksisprohibitedandconstitutesapunishableviolationofthelaw.Netscapemayrevisethisdocumentationfromtimetotimewithoutnotice.THISDOCUMENTATIONISPROVIDEDASISWITHOUTWARRANTYOFANYKIND.INNOEVENTSHALLNETSCAPEBELIABLEFORANYLOSSOFPROFITS,LOSSOFBUSINESS,LOSSOFUSEORDATA,INTERRUPTIONOFBUSINESS,ORFORINDIRECT,SPECIAL,INCIDENTAL,ORCONSEQUENTIALDAMAGESOFANYKIND,ARISINGFROMANYERRORINTHISDOCUMENTATION.TheSoftwareanddocumentationarecopyright?1994-1998NetscapeCommunicationsCorporation.Allrightsreserved.TheSoftwarecontainsJavaScriptsoftwaretechnologyinventedandimplementedbyNetscapeCommunicationsCorporation.TheJavaScriptnameisatrademarkorregisteredtrademarkofSunMicrosystems,Inc.intheUnitedStatesandothercountriesandisusedunderlicense.Netscape,NetscapeNavigator,NetscapeCertificateServer,NetscapeDevEdge,NetscapeFastTrackServer,NetscapeONE,SuiteSpotandtheNetscapeNandShip’sWheellogosareregisteredtrademarksofNetscapeCommunicationsCorporationintheUnitedStatesandothercountries.OtherNetscapelogos,productnames,andservicenamesarealsotrademarksofNetscapeCommunicationsCorporation,whichmayberegisteredinothercountries.Otherproductandbrandnamesaretrademarksoftheirrespectiveowners.Thedownloading,exportorreexportofNetscapesoftwareoranyunderlyinginformationortechnologymustbeinfullcompliancewithallUnitedStatesandotherapplicablelawsandregulations.AnyprovisionofNetscapesoftwareordocumentationtotheU.S.GovernmentiswithrestrictedrightsasdescribedinthelicenseagreementaccompanyingNetscapesoftware..RecycledandRecyclablePaperVersion1.4?1998NetscapeCommunicationsCorporation.AllRightsReservedPrintedintheUnitedStatesofAmerica.00999854321NetscapeCommunicationsCorporation,501EastMiddlefieldRoad,MountainView,CA94043NewFeaturesinthisReleaseJavaScriptversion1.4providesthefollowingnewfeaturesandenhancements:?Exceptionhandling.Youcanthrowandcatchexceptionsusingthethrowandtry……catchstatements.See“ExceptionHandlingStatements”onpage82.?Newoperatorsinandinstanceof.Theinoperatorreturnstrueifthespecifiedpropertyisinthespecifiedobject;see“in”onpage50.Theinstanceofoperatorreturnstrueifthespecifiedobjectisofthespecifiedobjecttype;see“instanceof”onpage50.?ChangestoLiveConnect.SeveralchangestoLiveConnectimprovethewayJavaandJavaScriptcodecommunicate:?JavaClassobjectsareautomaticallyconvertedtoinstancesofjava.lang.Classwhenyoupassthemasparameterstomethods.See“JavaClassobjects”onpage159.?Youcanpassaone-characterstringtoaJavamethodwhichrequiresanargumentoftypechar.See“ArgumentsofTypechar”onpage147.?IfyourJavaScriptcodeaccessesaJavadatamemberormethodandfails,theJavaexceptionispassedontoJavaScriptforyoutohandle.See“HandlingJavaExceptionsinJavaScript”onpage147.?EnhancementstotheJSExceptionclasschangethewayyouhandleJavaScriptexceptionsinyourJavacode.See“HandlingJavaScriptExceptionsinJava”onpage150.?ChangestotheFunctionobject.Youshouldnolongerspecifyafunctionnamewhenusingtheargumentsarray;theargumentsarrayisavariableandisnolongerapropertyofFunctionobjects.Thischangeimprovesperformance.See“UsingtheargumentsArray”onpage89.34CoreJavaScriptGuideContentsNewFeaturesinthisRelease……3AboutthisBook……11NewFeaturesinthisRelease……11WhatYouShouldAlreadyKnow……11JavaScriptVersions……12WheretoFindJavaScriptInformation……13DocumentConventions……14Chapter1JavaScriptOverview……15WhatIsJavaScript?……16JavaScriptandJava……17DebuggingJavaScript……18VisualJavaScript……19JavaScriptandtheECMASpecification……19RelationshipBetweenJavaScriptandECMAVersions……20JavaScriptDocumentationvs.theECMASpecification……21JavaScriptandECMATerminology……21Part1CoreLanguageFeaturesChapter2Values,Variables,andLiterals……25Values……25DataTypeConversion……26Variables……27DeclaringVariables……27EvaluatingVariables……27VariableScope……28ContentsvLiterals……29ArrayLiterals……29BooleanLiterals……30Floating-PointLiterals……31Integers……31ObjectLiterals……31StringLiterals……32Unicode……34UnicodeCompatibilitywithASCIIandISO……35UnicodeEscapeSequences……35DisplayingCharacterswithUnicode……37Chapter3ExpressionsandOperators……39Expressions……39Operators……40AssignmentOperators……41ComparisonOperators……41ArithmeticOperators……42BitwiseOperators……43LogicalOperators……45StringOperators……47SpecialOperators……47OperatorPrecedence……54Chapter4RegularExpressions……55CreatingaRegularExpression……56WritingaRegularExpressionPattern……56UsingSimplePatterns……57UsingSpecialCharacters……57UsingParentheses……62WorkingWith