• The Document Object Model (DOM) is an Application Programming Interface (API) for HTML and XML documents.
• With the Document Object Model, programmers can create and build documents, navigate their structure, and add, modify, or delete elements and content.
• The DOM is an object-oriented representation of the web page, which can be modified with a scripting language such as JavaScript.
• The DOM model represents a document with a logical tree.
• According to Document Object Model (DOM), every HTML-tag is an object. Nested tags are called “children” of the enclosing one. All operations on the DOM start with the document object. From it, we can access any node.
• The Document Object Model can be used with any programming language.

DOM Levels

• DOM Level 0 – This level supports the common document object collections – form[ ], image[ ], anchors[ ], links[ ] and applets[ ]. This is also known as classic or traditional JavaScript Object Model. •

• DOM Level 1- It provides the ability to manipulate all elements in a document through a common set of functions. In this level, all elements are exposed and parts of the page can be read and written to at all times.

• DOM Level 2 – It provides further access to page elements primarily related to CSS and focuses on combining Level 0 and Level 1 while adding improved support for working with XML documents.

DOM Levels

• DOM Level 3 – Enhanced Level of Level 1 and Level 2 and added support for XPath and keyboard event handling.

• DOM Level 4 – Enhanced  year 2015

Categories of DOM

• DOM Core – It specifies a generic model for viewing and manipulating a marked-up document as a tree structure.

• DOM HTML – It specifies an extension to the core DOM for use with HTML. This represents DOM Level 0 with capabilities for manipulating all of the HTML element objects.

• DOM CSS – It specifies the interfaces necessary to manipulate CSS rules programmatically.

• DOM Events – It adds event handling to the DOM.

• DOM XML – It specifies an extension to the Core Dom for use with XML.

Document Tree

DOM Node Types

Node Relationship

• Parent
• Children
• First Child
• Previous Sibling
• Next Sibling
• Last child

DOM Node Properties

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