Post on 27-Aug-2014
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JS Patterns
How to improve javascript code
Reminder :
3 categories design patterns :
-> Creational-> Structural-> Behavioral
Antipattern :
-> Wrong design -> Result of bad habit, bad practice, bad idea…
Best practice general :
Function Declarations : creating anonymous functions and assigning them to a variable
Implied Typecasing : avoid implied typecasting
Avoid eval() : "Eval is evil."
Best practice general :
Minimize Global (Not clear & unexpected results) / Hoisting
Working with Json (JavaScript Object Notation)
Use literal notation ( array & Regex)
Use parseInt()
Best practice – code reuse :
Use constructor / share prototype => use javascript object
Use functions :- Callback / Chaining Pattern - Configuration objects- Immediate functions (could be used to init object)
- Memoization : use function properties to avoid repeated computation
Design pattern - Creation - best practice :
Use Namespace : namespaces help reduce the number of globals required and avoid naming collisions or excessive name prefixing
Use Module / Declare dependencies
Use private Properties / Methodes / Static Members / Object constants
Use sandbox : it provides an environment for the modules to work without affecting other modules and their personal sandboxes
Design pattern – Creation :
Use Builder : constructs complex objects by separating construction and representation
Use Factory : creates objects without specifying the exact class to create
Design pattern – Structural :
Use Decorator : dynamically adds/overrides behaviourin an existing method of an object
Use Facade : provides a simplified interface to a large body of code
Proxy : provides a placeholder for another object to control access,reduce cost, and reduce complexity
Design pattern – Structural :
Design pattern – Behavioral :
Chain of responsibility : delegates commands to a chain of processing objects
Command : creates objects which encapsulate actions and parameter
Mediator : allows loose coupling between classes by being the only class that has detailed knowledge of their methods
Observer : is a publish/subscribe pattern which allows a number ofobserver objects to see an event
Strategy : allows one of a family of algorithms to be selected on-the-fly at runtime
jQuery :
requery : avoid requery by using jQuery chaining
append : use string concatenate and set innerHTML
append : use string concatenate and set innerHTML
detach : take element off the DOM while manipulating them
jQuery : selector cache : using selector cache to avoid requery
selector Left and Right - specific on the right, light on the left
Selector Decending from id : be more specific
Use publish / subscribe : $.Callbacks() & $.Observable
jQuery Plugin :
Basic : the most basic pattern
Extend : enables you to define multiple functions at once and which sometimes make more sense semanticall
jQuery :
UI Widget factory : for building complex, stateful plugins based on object-oriented principles
References :
http://shichuan.github.io/javascript-patterns/#general-patterns
JavaScript Patterns – O’REILLY
http://api.jquery.com/
http://www.codetails.com/2014/05/27/top-10-javascript-traps-for-a-c-developer/
Learning JavaScript Design Patterns – O’REILLY
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