Book Image

Mastering JavaScript

By : Ved Antani
Book Image

Mastering JavaScript

By: Ved Antani

Overview of this book

JavaScript is a high-level, dynamic, untyped, lightweight, and interpreted programming language. Along with HTML and CSS, it is one of the three essential technologies of World Wide Web content production, and is an open source and cross-platform technology. The majority of websites employ JavaScript, and it is well supported by all modern web browsers without plugins. However, the JavaScript landscape has changed dramatically in recent years, and you need to adapt to the new world of JavaScript that people now expect. Mastering modern JavaScript techniques and the toolchain are essential to develop web-scale applications. Mastering JavaScript will be your companion as you master JavaScript and build innovative web applications. To begin with, you will get familiarized with the language constructs and how to make code easy to organize. You will gain a concrete understanding of variable scoping, loops, and best practices on using types and data structures, as well as the coding style and recommended code organization patterns in JavaScript. The book will also teach you how to use arrays and objects as data structures. You will graduate from intermediate-level skills to advanced techniques as you come to understand crucial language concepts and design principles. You will learn about modern libraries and tools so you can write better code. By the end of the book, you will understand how reactive JavaScript is going to be the new paradigm.
Table of Contents (16 chapters)
Mastering JavaScript
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

The event object


So far, we attached anonymous functions as event handlers. To make our event handlers more generic and useful, we can create named functions and assign them to the events. Consider the following lines:

function handlesClicks(event){
  //Handle click event
}
$("#bigButton").on('click', handlesClicks);

Here, we are passing a named function instead of an anonymous function to the on() method. Let's shift our focus now to the event parameter that we pass to the function. jQuery passes an event object with all the event callbacks. An event object contains very useful information about the event being triggered. In cases where we don't want the default behavior of the element to kick in, we can use the preventDefault() method of the event object. For example, we want to fire an AJAX request instead of a complete form submission or we want to prevent the default location to be opened when a URL anchor is clicked on. In these cases, you may also want to prevent the event from bubbling...