Javascript Design Patterns?

Question

Web developers frequently interact with design patterns, even unknowingly, when creating applications.

So what is Design Patterns?

Design patterns are advanced object-oriented solutions to commonly occurring software problems.  Patterns are about reusable designs and interactions of objects. 

List of Design Patterns

• Constructor Pattern
• Module Pattern
• Revealing Module Pattern
• Singleton Pattern
• Observer Pattern
• Mediator Pattern
• Prototype Pattern
• Command Pattern
• Facade Pattern
• Factory Pattern
• Mixin Pattern
• Decorator Pattern
• Flyweight Pattern

Four Design Patterns Developers need to know

1. Module
2. Prototype
3. Observer
4. Singleton 

Module Pattern

Modules should be Immediately-Invoked-Function-Expressions (IIFE) to allow for private scopes – that is, a closure that protect variables and methods.

Example : 

(function() {

    // declare private variables and/or functions

    return {
      // declare public variables and/or functions
    }

})();

Prototype Pattern

The Prototype Pattern creates new objects, but rather than creating non-initialized objects it returns objects that are initialized with values it copied from a prototype - or sample - object. The Prototype pattern is also referred to as the Properties pattern.​

var class1= function() {
  this.var1    = 4;
  this.var2    = 4;
}

class1.prototype.method1 = function() {
  
}

class1.prototype.method2 = function() {
  
}

Observer Pattern

There are many times when one part of the application changes, other parts needs to be updated. In AngularJS, if the $scope object updates, an event can be triggered to notify another component. The observer pattern incorporates just that – if an object is modified it broadcasts to dependent objects that a change has occurred.​

Singleton  Pattern

A Singleton only allows for a single instantiation, but many instances of the same object. The Singleton restricts clients from creating multiple objects, after the first object created, it will return instances of itself.

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