Head First JavaScript Programming, 2nd Edition

Chapter 11. Modern Syntax, Lexical Scope, and Closures: Serious functions

You’ve put functions In this chapter, we take it further; we get hard-core. We’ll show you how to up your syntax game with advanced techniques for handling arguments, parameters, and assignments. We’ll then take another look at scope and some of the finer points of how JavaScript manages it. This journey through the subtleties of scope brings us to the heart of closures—a concept often shrouded in mystery but pivotal in mastering JavaScript. In the end, you’ll be more expressive with your JavaScript than you thought possible. through their paces, but there’s more to learn.

Note

And if you have heard of a closure but don’t quite know what it is, you’re in the right place!

Getting serious about functional syntax

You might think at this point there is nothing else to know about basic function syntax, but there are actually a number of syntactic enhancements that have been added to JavaScript that can make your use of functions even more straightforward and expressive. Before we get down to talking about scope and closures, let’s make sure you’re up to speed on everything you can do when calling and receiving values from functions.

Streamlining code with default parameters

Let’s say we have a function, ...