Patterns In-Javascript

Patterns In-Javascript

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  Patterns in Javascript Prototype& Module Patterns Presentation By : Ashutosh Mahto Mindfire Solutions
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  Patterns In Javascript Agendato Discuss 1. Why to concern about design patterns in Javascript? 2. Before we begin what needs to be known? 3. Prototype Pattern – Structure, Advantages & Drawbacks 4. Module Pattern – Structure, Advantages & Drawbacks 5. Some Enhanced Patterns – Revealing Module Pattern Revealing Prototype Pattern
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  Patterns In Javascript Whya Design Pattern 1. Scattered variables and function 2. Conflicts may arise between variables and methods 3. Difficult to manage when code becomes larger 4. Often result into repeated functions for similar purpose
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  Patterns In Javascript Whya Design Pattern ”A pattern is a reusable solution that can be applied to commonly occurring problems in software design” Benefits of choosing a design pattern 1. Patterns are proven solutions 2. Patterns can be easily reused 3. Patterns can be expressive
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  Patterns In Javascript Beforewe begin Namespaces - Reduces number of globals and chance of scattered globals - Avoids naming conflicts Ex. var MFLib = MFLib || {}; Closures - Local variables for a function are kept alive after the function has returned - Used widely to differentiate public and private members in javascript Public and Private members in Javascript - Javascript doesn't have special syntax for public and private - Can be implemented using closures
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  Patterns In Javascript Beforewe begin Prototypes - Prototype is the base of Object Oriented Programming in javascript - Every function contains a prototype object that can be chained through its constructor. var Person= function(name) { this.name = name; } Person.prototype.getName = function() { return this.name; } var student = new Person("Satish");
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  Patterns In Javascript PrototypePattern : Structure Prototype For Product MFLib.Product = function (name) { this.Id = ''; } MFLib.Product.prototype.setPrice = function (price) {} MFLib.Product.prototype.setDescription = function (description) {}
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  Patterns In Javascript PrototypePattern : Advantages & Drawbacks Advantages 1. Modularizes and isolates the code 2. Separates related variables and methods from global context 3. Easy to be extended through prototype Drawbacks 1. Restricts access to private members
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  Patterns In Javascript ModulePattern : Structure Shopping Cart Module MFLib.ShoppingCart = (function () { /* Private Variables */ var _basket = []; /* Private Method */ function getShoppingCartTotal() {} return { CreateBasketItem: function () {}, AddItem: function () {}, RemoveItem: function () {}, GetTotal: getShoppingCartTotal }; })();
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  Patterns In Javascript ModulePattern : Structure Shopping Cart Module MFLib.ShoppingCart = (function () { /* Private Variables */ var _basket = []; /* Private Method */ function getShoppingCartTotal() {} return { CreateBasketItem: function () {}, AddItem: function () {}, RemoveItem: function () {}, GetTotal: getShoppingCartTotal }; })();
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  Patterns In Javascript ModulePattern : Important Points Global Import By passing globals as parameters to our anonymous function, we import them into our code MFLib.ShoppingCart = (function ($,window,document,undefined) { })(jQuery,window,document,undefined); Augmentation MFLib.ShoppingCart = (function (self, utilities) { self.Save = function () {} return self; })(MFLib.ShoppingCart, MFLib.Utilities);
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  Patterns In Javascript ModulePattern : Advantages & Drawbacks Advantages 1. Modularizes and isolates the code 2. Separates related variables and methods from global context 3. Establishes control over public and private members Drawbacks 1. Performance wise not good as Prototype pattern 2. Large code may result into repeated function 3. Not easy to extend
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  Patterns In Javascript SomeEnhanced Patterns : Revealing Module Pattern ”Enhancement to module pattern in which private members are also exposed” Important points : 1. Benefits when we need to have some private members exposed 2. Private functions remain protected even if public functions get modified by some chance. Ex. ShoppingCart.GetTotal = null;
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  Patterns In Javascript SomeEnhanced Patterns : Revealing Prototype Pattern ”Combination of Prototype pattern and Module pattern” Important points : 1. Better performance than Module Pattern 2. Include prototypes to define the methods in a module 3. Exposes members through prototype
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  Patterns In Javascript AnyQuestion ???
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  Patterns In Javascript Referencesand Recommendations  Books − Javascript The Good Parts, Douglas Crockford − Javascript: The Definitive Guide, David Flanagan − Professional Javascript For Developers, Nicholas Zakas  Blogs  Articles  Stack Overflow Get in touch with : − Douglas Crockford − Nicholas Zakas − Addy Osmani − Paul Irish
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  Patterns In Javascript ThankYou !!!