Book Image

Javascript Unlocked

Book Image

Javascript Unlocked

Overview of this book

JavaScript stands bestride the world like a colossus. Having conquered web development, it now advances into new areas such as server scripting, desktop and mobile development, game scripting, and more. One of the most essential languages for any modern developer, the fully-engaged JavaScript programmer need to know the tricks, non-documented features, quirks, and best practices of this powerful, adaptive language. This all-practical guide is stuffed with code recipes and keys to help you unlock the full potential of JavaScript. Start by diving right into the core of JavaScript, with power user techniques for getting better maintainability and performance from the basic building blocks of your code. Get to grips with modular programming to bring real power to the browser, master client-side JavaScript scripting without jQuery or other frameworks, and discover the full potential of asynchronous coding. Do great things with HTML5 APIs, including building your first web component, tackle the essential requirements of writing large-scale applications, and optimize JavaScript’s performance behind the browser. Wrap up with in-depth advice and best practice for debugging and keeping your JavaScript maintainable for scaling, long-term projects. With every task demonstrated in both classic ES5 JavaScript and next generation ES6-7 versions of the language, Whether read cover-to-cover or dipped into for specific keys and recipes, JavaScript Unlocked is your essential guide for pushing JavaScript to its limits.
Table of Contents (15 chapters)
JavaScript Unlocked
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Event handling optimization


It must have happened to you while writing a form inline validator that you run into a problem. As you type it, the user-agent keeps sending validation requests to the server. This way you might quickly pollute the network with spawning XHRs. Another sort of problem that you may be familiar with, is that some UI events ( touchmove, mousemove, scroll, and resize ) are fired intensively and subscribed handlers may overload the main thread. These problems can be solved using one of two approaches known as debouncing and throttling. Both functions are available in third-party libraries such as Underscore and Lodash (_.debounce and _.throttle). However, they can be implemented with a little o code and one doesn't need to depend on extra libraries for this functionality.

Debouncing

By debouncing, we ensure that a handler function is called once for a repeatedly emitted event:

  /**
   * Invoke a given callback only after this function stops being called `wait` milliseconds...