# JavaScript: JS in WebBrowser and basic DOM manipulations Client-side JavaScript code is embedded within HTML documents in four ways: * Inline, between a pair of and tags * From an external file specified by the src attribute of a tag ```markup ``` * In an HTML event handler attribute, such as onclick or onmouseover ```markup ``` * In a URL that uses the special javascript: protocol. ```markup What time is it? ``` The Document Object Model, or DOM, is the fundamental API for representing and manipulating the content of HTML and XML documents. The API is not particularly complicated, but there are a number of architectural details you need to understand. First, you should understand that the nested elements of an HTML or XML document are represented in the DOM as a tree of objects. The tree representation of an HTML document contains nodes representing HTML tags or elements, such as and , and nodes representing strings of text. An HTML document may also contain nodes representing HTML comments. Consider the following simple HTML document: ```markup Sample Document

An HTML Document

This is a simple document. ``` The DOM representation of this document: ![](https://3408508746-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lis5JLcnSD2vdYdyQ3U%2F-LkOYfABkB-7M5VssiAH%2F-LkOZ5_JR7FXR5qYyz38%2Fimage.png?alt=media\&token=54f42f88-cdf0-4657-82cc-bf610c891c11)