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From there on, the event bubbles up to containing elements before going to those even higher up. For our first practical example, imagine we have a Periochip (Chlorhexidine Chip for Insertion into Periodontal Pockets)- Multum of similar elements in a document with similar behavior executed when a user-action (e.

Normally what we do when constructing our own accordion component, menu or other list-based widget is bind a click event to each link element in the parent container (e. Instead of binding the click to multiple elements, we can easily attach a Flyweight to the top of our container which can listen for events coming from below.

These can then Periochip (Chlorhexidine Chip for Insertion into Periodontal Pockets)- Multum handled using logic that is as simple or complex as required. As the types of components mentioned often have the same repeating markup for each section (e. We'll use this information to construct a very basic accordion using the Flyweight below.

A stateManager johnson dc751 is used here to encapsulate our flyweight logic whilst jQuery is used to bind the initial click to a container div. In order to ensure that no other shane johnson on the page is attaching similar handles to the container, an unbind event is first applied.

Now to establish exactly what child element in the container is clicked, we make use of a target check which provides a reference to the element that was clicked, regardless of its parent. We then use this information to handle the click event without actually needing to bind the event to specific children when our page loads. In our second example, we'll reference some further performance gains that can be achieved using Flyweights with jQuery. The idea here is that a single jQuery object is created and used for each call to jQuery.

The implementation for this can be found below and as we're consolidating data for Periochip (Chlorhexidine Chip for Insertion into Periodontal Pockets)- Multum possible objects into a more central singular structure, it is technically also a Flyweight.

That's not to say don't apply any caching at all, just be mindful that this approach can assist. In this section, we're going to review three very important architectural patterns - MVC (Model-View-Controller), MVP (Model-View-Presenter) and MVVM (Model-View-ViewModel). In the past, these patterns have been heavily used for structuring desktop and server-side applications but it's only been in recent years that come to being applied to JavaScript.

As the majority of JavaScript developers currently using these patterns opt to utilize libraries such as Backbone. MVC is an architectural design pattern that encourages improved application organization through a separation of concerns.

It enforces the isolation of business data (Models) from user interfaces (Views), with a third component (Controllers) traditionally managing logic and user-input. The pattern was originally designed by Trygve Reenskaug during his time working on Smalltalk-80 (1979) where it was initially called Model-View-Controller-Editor. It's important to understand what excess original MVC pattern was aiming to solve as it's mutated quite heavily since the days of its origin.

Back in the 70's, graphical user-interfaces were few and far between and a concept known as Separated Presentation began to be used as a means to make a clear division between domain objects which modeled concepts in the real world (e.

The Smalltalk-80 implementation of MVC took this concept further and had an objective of separating out the application logic from the user interface. The idea was that decoupling these parts of the application would also allow the reuse of models for other interfaces in the application.

In Smalltalk-80's MVC, the View observes the Model. As mentioned in the bullet point above, anytime the Model changes, the Views react. A simple example of this is an application backed by stock market data - in order for the application to be useful, any change to u 200 data in our Models should result in the View being refreshed instantly.

Martin Fowler has done an excellent job of writing about the origins of MVC over the years and if interested in some further historical information about Smalltalk-80's MVC, I recommend reading his work. We've reviewed the 70's, but let us now return to the here and now.

In abbott laboratories logo times, the MVC pattern has been applied to a diverse range of programming languages including of most relevance to us: JavaScript.

Periochip (Chlorhexidine Chip for Insertion into Periodontal Pockets)- Multum frameworks include the likes of Backbone, Ember. Given the importance of avoiding "spaghetti" code, a term which describes code that is very difficult to read or maintain due to its lack of structure, it's imperative that the modern JavaScript developer understand what Periochip (Chlorhexidine Chip for Insertion into Periodontal Pockets)- Multum pattern provides.

This allows us to effectively appreciate what these frameworks enable us to do differently. Models manage the data for an application. They are concerned with neither the user-interface nor presentation layers but instead represent unique forms of data that an application may require. When a model changes (e.

To understand models further, let us imagine we have a JavaScript photo gallery application. In a photo gallery, the concept of a photo would merit its own model as it represents a unique kind of domain-specific data. Such a model may contain related attributes such as a caption, image source and additional meta-data. A specific photo would be stored in an instance of a model and a model may also be reusable.

Below we can see an example of a very simplistic model implemented using Backbone. When using models in real-world applications we generally also desire model persistence. Persistence allows us to edit and update models with the knowledge that its most recent state will be saved in either: memory, in a user's localStorage data-store or synchronized with a database.

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