The W3C Document Object Model was an early effort to gain fine-grained control over a document in memory. This hack introduces you to how DOM works.
The Document Object Model or DOM (http://www.w3.org/DOM/) is a W3C-specified recommendation set that provides facilities to “allow programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page” (http://www.w3.org/DOM/#what). In other words, DOM is a tree-based API that allows you to pick an XML document (or HTML document) apart into its constituent parts, examine those parts, change them, and stuff them back into a document.
The first release of DOM came out in 1998 as a single document, with a second edition appearing in 2000 (http://www.w3.org/TR/2000/WD-DOM-Level-1-20000929/). Level 2 of DOM appeared later in 2000 and consists of not less than six modules: Core, Views, Events, Style, Traversal, Range, and HTML. You can get the whole package in a single ZIP archive at http://www.w3.org/2001/05/level-2-src.zip. Level 3 just reached recommendation status. It adds a Validation module (http://www.w3.org/TR/DOM-Level-3-Val/) and a Load and Save module (http://www.w3.org/TR/DOM-Level-3-LS/). It also updates the Core module (http://www.w3.org/TR/DOM-Level-3-Core/).
DOM represents documents as a hierarchy or tree of nodes. ...