This is slides for Patterns in JavaScript

1. Patterns in JavaScript
@debug_mode

2. Agenda
Start with Object
Functions
Constructor Pattern
Prototype Pattern
Invocation Patterns
Revealing Prototype Pattern
Revealing Module Pattern

3. Your Presenter
 Dhananjay Kumar
– 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
Object literal 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 new operator
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 a static function
It always has two
parameters
• Prototype
• Properties

8. JavaScript Functions
Anonymous functions should
be assigned to a variable

9. Nested Functions
 Nested function 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 in Functions

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
This is 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?