JavaScript® Programmer's Reference

Chapter 9. The Array and Date Objects

At this point you've covered all of the primitive data types in JavaScript, including strings, booleans, numbers, and even null and undefined. Now you'll circle back and dive into the two remaining reference types: arrays and dates. Arrays are one of the more sophisticated types, and they allow you to group together ordered and unordered sets of values, along with some useful tools for working with those sets. Dates provide a full-featured interface to localized date and time values. Together they complete your understanding of the core data types in JavaScript.

The Array Object

The behavior of arrays has changed somewhat since the first versions of JavaScript. Today they are full-featured structures for storing and working with both ordered and unordered sets of values. They can be used to store both primitives and object references, can be resized and reordered, and are about as flexible as one can imagine (certainly they are more flexible than you may be used to). The JavaScript Array object is sometimes said to be more of an array-like structure than a traditional one. While it lacks some of the performance advantages of normal arrays, it is an extremely powerful tool that you will no doubt come to rely on. This section covers both the built-in features of arrays as well as some techniques for getting a little extra functionality out of them in a lightweight, cross-browser way.

Array Object Overview

Arrays are reference types, and they are implemented ...