What is DOM?

The Document Tree

The DOM (Document Object Model) document tree is a type of tree-like structure that is used to represent HTML and XML documents. It is the foundation for modern web development, forming the basis for all styling and scripting languages such as JavaScript and CSS.

At a basic level it is important to understand that the DOM document tree contains a hierarchy of elements and nodes: each element or node contains individual pieces of data, whether that be text, images, links, etc., which can all be manipulated with code. Every piece of code written in a modern web environment interacts with elements in the DOM document tree; therefore, learning the basics of this structure is essential for any beginning web developer.

Element Nodes

Element Nodes are the individual elements within the DOM document tree. These are organized into a hierarchical structure, with various nodes representing different types of data. The most common type of Element Nodes are HTML tags, such as div or p, which represent separate sections or blocks of code on a web page.

Element Nodes can also contain additional attributes, like ID and class, that allow developers to target specific pieces of content in their code. Node Attributes can also be used to provide extra context for elements, helping developers understand how they are being styled and manipulated by code.

Ultimately, all web development is based around manipulating these Element Nodes; so it is important for beginners to understand the basics of these nodes in order to design more complex websites and applications.

Attribute Nodes

Attribute Nodes are nodes within the DOM that contain specific information about an element. Each Attribute Node contains a key-value pair, with the key being the name of the attribute and the value being its associated data. Examples of these key-value pairs include an Element Node’s ID (key=id, value=the element’s specific ID) or a class name (key=class, value=the name of a class). These attributes provide additional context for developers in identifying elements on webpages and manipulating them with code. Understanding how to use these attributes is essential to creating complex websites and applications.

Text Nodes

Text Nodes are the leaf nodes of the DOM, meaning they contain all text content within an element. This includes both plain text and HTML tags, like paragraph tags or heading tags. Text Nodes can also be used to add additional context and structure to a webpage, like adding titles and headings, since they contain the text that will appear onscreen.

Furthermore, when manipulating elements via JavaScript code, elements must be targeted by traversing through their parent Node’s child Nodes – including Text Nodes – which can help identify the appropriate element on a page for manipulation.

Event Listeners

Event Listeners allow us to specify which actions should be taken when certain events occur within the DOM such as clicking on a link or hovering over an element with the mouse cursor.  By using Event Listeners, we are adding interactivity to a website.  We attach an Event Listener to an element by using the “addEventListener” method and specifying which type of event should be listened for as well as which function should be executed when that event is detected.

Building Blocks of the Web

Knowledge of the DOM allows developers to create dynamic experiences on a website, allowing users to interact with elements in intuitive ways. Through understanding the fundamentals of the DOM, developers will be able to make websites that are more interactive and engaging than ever before.