Patterns in JavaScript

Patterns in JavaScript

• 1.
  Patterns in JavaScript @debug_mode
• 2.
  Agenda Start with Object Functions ConstructorPattern Prototype Pattern Invocation Patterns Revealing Prototype Pattern Revealing Module Pattern
• 3.
  Your Presenter  DhananjayKumar – Evangelist , Telerik – Microsoft MVP – Mindcracker MVP – @debug_mode – http://debugmode.net – http://telerikhelper.net – Dhananjay.kumar@telerik.com
• 4.
  JavaScript Objects Using Literals Using New Operator Using Object.create()
• 5.
  Object as Literal Objectliteral is an expression It creates new object each time it appears in the code A single object literal can create many objects in loop
• 6.
  Object using newoperator new operator creates a new object new operator initialize created object also new operator invokes a function as give in above code snippet. Function invoked after new operator is Constructor
• 7.
  Object.create() It is astatic function It always has two parameters • Prototype • Properties
• 8.
  JavaScript Functions Anonymous functionsshould be assigned to a variable
• 9.
  Nested Functions  Nestedfunction can access variable of parent function  Parent function cannot access variable of nested function  You cannot call nestedfunction from anywhere but the function it is nested within.
• 10.
  Passing Variables inFunctions
• 11.
  Invocations Patterns Function Invocation Pattern Method Invocation Pattern Constructor Invocation Pattern InDirect Invocation Pattern
• 12.
  Function Invocation Pattern When you call a function as an expression then it is known as Function Invocation Pattern  First each parameter gets evaluated and then being passed as argument to function  Function return either value or undefined to LHS variable .If called function does not have any return value then it returns undefined
• 13.
  Method Invocation Pattern Function which is part of an object is known as Method  Invocation of method is known as Method Invocation Pattern  A method can access its parent object with this operator  Binding of method to object happens on execution of method
• 14.
  Indirect Invocation Pattern Call() method Apply() method Direct method
• 15.
  Revealing Prototype Pattern Thisis normally we implement it ,  It is hard to maintain when functionality grows  It is hard to debug  It is hard to test
• 16.
  Revealing Prototype Pattern Code is reusable  Functions can be overridden by prototyping  There are no variables or functions in global namespace  Functions are loaded into memory only once
• 17.
  Revealing Prototype Pattern: Overriding
• 18.
  Revealing Module Pattern To Achieve Private/Public  To Achieve Singleton  To remove singleton , remove selfexecutable code
• 19.
  Questions?