There is no one single practical reference for JavaScript/DOM. JavaScript, CSS, DOM are developed out of competing browser implementations since ≈1996. Later, a standard bodies arose and tried to standardize these tech. However, the references and documentations from standard bodies, such as W3C, have little relevance for practical JavaScript coding. (They are useful only if you are implementing the browser.) If your code is complex, testing with different browsers is necessary.
W3C Markup Validation Service @ validator.w3.org….
W3C CSS Validation Service @ jigsaw.w3.org….
The standard for JavaScript is called ECMAScript, known as “ECMA-262”. The different standardized JavaScript versions are known as “ECMA-262” editions. As of , the current edition is 5.1.
A good JavaScript validation service is at www.jslint.com
Document Object Model (DOM) is supposed to be a abstract document model. However, in practice, it is just used for scripting HTML/XML, and is really just part of the language of JavaScript. Most coding of JavaScript is about understanding DOM.
As of , for practical purposes, some 98% of DOM Level 2 is implemented across browsers.