Chapter 3. Arrays and Objects


Most programming tasks involve moving data around in memory. A lot of the data involved in browser-based JavaScript activity consists of objects that are part of the rendered document. But very often your scripts arrive at the client accompanied by data provided by a server or hardwired in the script (as arrays or custom objects). Or you may find it convenient to create more flexible data structures that mirror the rendered content on the page. For example, it may be easier and faster to sort a table’s data inside a JavaScript array and re-render the table rather than playing Tower of Hanoi games with cells and rows of a table one by one.

One of the most important jobs you have as a programmer is designing the data structures that your scripts will be working with. It’s not unusual to start the planning of a major scripting job by scoping out the data structures that will facilitate DHTML enhanced user interface features. When you do so, you will find JavaScript arrays and custom objects to be the containers and organizers of your data. These containers give your scripts a regular way to access the data points and a clean way to structure the data to make it easy to visualize the abstract comings and goings during script execution.

JavaScript Arrays

The loose data typing that pervades JavaScript carries over to arrays, but even more so. Unlike similar structures in many other programming languages, a JavaScript array is not limited to a specific ...

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