1. 1 | SharePoint Saturday Milan – 18 May 2013

2. 2 | SharePoint Saturday Milan – 18 May 20132 | SharePoint Saturday Milan – 18 May 2013
Grazie ai nostri Sponsor!

3. 3 | SharePoint Saturday Milan – 18 May 2013
Salvatore Di Fazio – Technical Architect – Content and Code -
London
salvatore.difazio@gmail.com - @Salvodif – MVP SharePoint Server
http://salvatoredifaziosharepoint.blogspot.com

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Horizontal session

5. 5 | SharePoint Saturday Milan – 18 May 20135 | SharePoint Saturday Milan – 18 May 2013
Starter
 JavaScriptisobjectbasedlanguage
 Variablescreatedusingvar
 Youshouldalwaysusesemicolons,andanobjectisacollection ofname/value
 JavaScriptiscasesensitive
 Alwaysusestrictmode,declaredwith“usestrict”
 Restrictions
 Cannotuseavariablewithoutdeclaringit
 Cannotwritetoaread-onlyproperty
 Cannotaddpropertiestonon-extensibleobjects
 Cannotillegallydeletefunctionsandvariables
 Cannotdefineapropertymorethanonceinanobjectliteral
 Cannotuseaparameternamemorethanonceinafunction
 Cannotusereservedwords,eval,orarguments,asnamesforfunctionsandvariables
 Thevalueofthisinafunctionisnolongerthewindowobject
 Cannotdeclarefunctionsinsideofstatements
 Cannotchangethemembersoftheargumentsarray

6. 6 | SharePoint Saturday Milan – 18 May 20136 | SharePoint Saturday Milan – 18 May 2013
Null and undefined
 NULL
 OneoftheJavaScriptprimitive types
 Representstheabsenceofvalue
 EvaluatestofalseinBooleanexpressions
 UNDEFINED
 Primitivetype
 Representsanunknownvalue
 Returnedwhenanon-existentobjectpropertyiscalled
 EvaluatestofalseinBooleanexpressions

7. 7 | SharePoint Saturday Milan – 18 May 20137 | SharePoint Saturday Milan – 18 May 2013
Avoid coercive equality
operators
 Objectsareonlyequaltothemselves
 Primitivesareequalifthevaluesmatch(“salvo”===“salvo”)
 Twosetsofequalityoperators(==and===)
 Neveruse==or!=INSTEADof===or!==
0=='0' //true
0==='0' //false
false=='0' //true
false==='0' //false

8. 8 | SharePoint Saturday Milan – 18 May 20138 | SharePoint Saturday Milan – 18 May 2013
Prototype
 JavaScriptdoeshaveinheritanceandusuallymakeuseofprototype
 EveryJavaScriptobjecthasaninternalpropertycalledprototype
 obj.hasOwnProperty('propName')
 Toavoidtheduplicationofeffortandsavememory,ucanaddcommonproperties
andmethodstotheprototypeproperty.
 It’sbestifyoudon’taugmentbuilt-inprototypes.Youcanmakeanexceptionwhen:
1.it’sexpectedthatfutureEMACScriptversionswhilewaitingforthebrowserto
catchup
2.Youcheckifyourcustompropertyormethoddoesn’texistalready
3.Youclearlydocumentandcommunicatethechangewiththeteam

9. 9 | SharePoint Saturday Milan – 18 May 2013
Null, undefined, equality, prototype

10. 10 | SharePoint Saturday Milan – 18 May 201310 | SharePoint Saturday Milan – 18 May 2013
Functions
 Afunctionstartwiththekeywordfunction
 Afunctioncanhaveanameornot
 Afunctioncanhaveparameters
 Thedelimitersofthefunctionare{}
 Afunctioncanreturnavalue,andthatvaluecanbeitself
 Cannotbeoverloaded!!!
 Parametersnotpassedaresettedundefined
 Functionwithoutparametershasadefaultparamcalled(arguments)
 It’spossibletohaveafunctioninsideafunctionClosure
 Functionshavethis

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Closure Pattern
 Wheneveryouseethefunctionkeywordwithinanotherfunction,theinnerfunction
hasaccesstovariablesoftheouterfunction
 Whyuseit:
 itisthelocalvariablesforafunction—keptaliveafterthefunctionhasreturned
 itisastack-framewhichisnotdeallocatedwhenthefunctionreturns

12. 12 | SharePoint Saturday Milan – 18 May 201312 | SharePoint Saturday Milan – 18 May 2013
Classes Pattern
 WecreateaclassinJavaScriptbyapattern
 Useittopreventnamecollisionsandpollutingparentnamespace
 Keepeverythingtidy
 Usethenewkeywordtoinvoketheconstructor

13. 13 | SharePoint Saturday Milan – 18 May 201313 | SharePoint Saturday Milan – 18 May 2013
Module Pattern
 Thewindowobjectinbrowsersisaglobalnamespace
 Variablesdefinedoutsideafunctionareintheglobalnamespace
 Variablesdefinedwithoutthevarkeywordareintheglobalnamespace
 Alwayscreateyourownnamespacebyapattern
 ThemodulepatternwasmadebyEricMiragliaofYUIinthe2007
 Useittopreventnamecollisionsandpollutingparentnamespace
 Itprovidesstructureandhelpsorganizeyourcodeasitgrows
 It’sacombinationofthefollowingpatterns:
 Namespaces
 Immediatefunctions
 Privateandprivilegedmembers
 Declaringdependencies

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Decorator Pattern
 Itsolvestheproblemofaddingorchangingfunctionalityonaclasswithoutcreatinga
subclassforeverycombinationoffunctionality
 Everytimeyouaddanewoption,youcreateonlyonemoreclass,ratherthan
doublingthenumberofclasses.
 Thedecoratorworksbywrappingthebaseobjectwithadecoratorobjectthathasthe
sameinterfaceasthebaseobject

15. 15 | SharePoint Saturday Milan – 18 May 2013
Closure, Class, Module, Chain, Decorator

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Some references
 Problemsaboutglobals:http://blah.winsmarts.com/2013-5-SharePoint_2013_-
_JavaScript_-and-amp;_jQuery_big_booboo_to_watch_out_for.aspx
 JavaScriptPatterns:http://www.amazon.co.uk/dp/0596806752/?tag=hydra0b-
21&hvadid=9550950789&ref=asc_df_0596806752

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Session Feedback
JavaScript Patterns
http://www.surveymonkey.com/s/PNC3CLW

19. 19 | SharePoint Saturday Milan – 18 May 2013
Grazie