Book Image

jQuery Design Patterns

By : Thodoris Greasidis
Book Image

jQuery Design Patterns

By: Thodoris Greasidis

Overview of this book

jQuery is a feature-rich JavaScript library that makes HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a variety of browsers. With a combination of versatility and extensibility, jQuery has changed the way that millions of people write JavaScript. jQuery solves the problems of DOM manipulation, event detection, AJAX calls, element selection and document queries, element attribute and data management, as well as object management utilities. This book addresses these problems and shows you how to make the best of jQuery through the various design patterns available. The book starts off with a refresher to jQuery and will then take you through the different design patterns such as facade, observer, publisher/subscriber, and so on. We will also go into client-side templating techniques and libraries, as well as some plugin development patterns. Finally, we will look into some best practices that you can use to make the best of jQuery.
Table of Contents (18 chapters)
jQuery Design Patterns
About the Author
About the Reviewer

Writing performant CSS selectors

Even though Sizzle (jQuery's selector engine) hides the complexity of DOM traversals based on complex CSS selectors, we should have an idea of how our selectors are performing. Understanding how CSS selectors are matched against the elements of the DOM helps us write more efficient selectors which perform better when used with jQuery.

The key characteristic of efficient CSS selectors is specificity. According to this, ID and Class selectors are always more efficient than selectors with many results like div and *. When writing complex CSS selectors, keep in mind that they are evaluated from the right to the left and that a selector gets rejected after recursively testing it against every parent element until the root of the DOM.

As a result, try to be as specific as possible with the rightmost selector in order to cut down the matched elements as quickly as possible during the execution of the selector.

// initially matches all the anchors of the page 
// and...