Web Coding & Development All-in-One For Dummies

Chapter 5

Harnessing the Power of Functions

IN THIS CHAPTER

Getting to know JavaScript functions

Creating and using custom functions

Passing and returning function values

Understanding recursive functions

Introducing JavaScript’s built-in functions

To iterate is human, to recurse divine.

— L. PETER DEUTSCH

As I demonstrate throughout this book, JavaScript comes with a huge number of built-in features that perform specific tasks. For example, something called the Math object has a built-in method for calculating the square root of a number. Similarly, a feature called the String object has a ready-made method for converting a string value to all lowercase letters.

There are, in fact, hundreds of these ready-to-roll features that perform tasks that range from the indispensable to the obscure. But JavaScript can't possibly do everything that you’d like or need it to do. What happens if your web development project requires a particular task or calculation that isn’t part of the JavaScript ...