Unit-3: Web technologies P.R.Engineering college

Unit-3: Web technologies in Web technology - Subject uploaded at P.R.Engineering college

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UNIT III
Host Objects:-
 JavaScript supports three types of objects: native, host, and user-defined. Native objects are objects
supplied by the JavaScript language. String, Boolean, Math, and Number are examples of native objects.
Host objects are JavaScript objects that provide special access to the host environment. They are provided
by the browser for the purpose of interaction with the loaded document. In a browser environment,
1. window
2. document
objects are host objects. Several other browser host objects are informal, de facto standards. They are: 
alert, prompt, confirm.
DOM
• The Document Object Model (DOM) is an API that allows programs to interact with HTML (or
XML) documents
• The primary function of the Document Object Model is to view, access, and change the structure
of an HTML document separate from the content contained within it.
• The DOM will provide you with methods and properties to retrieve, modify, update, and delete
parts of the document you are working on. The properties of the Document Object Model are used
to describe the web page or document and the methods of the Document Object Model are used
for working with parts of the web page.
 In DOM, HTML document is represented in tree like structure. It constructs a hierarchical tree
structure for a HTML document to traverse and to manipulate the document.
• For example,
<html>
<head>
<title>Sample Document</title>
</head>
<body>
<h1>An HTML Document</h1>
<p>This is a <i>simple</i> document.IT 2353 WEBTECHNOLOGY PREC
2
</body>
</html>
The DOM representation of this document is as follows:
The node directly above a node is the parent of that node. The nodes one level directly below another 
node are the children of that node. Nodes at the same level, and with the same parent, are siblings. The set 
of nodes any number of levels below another node are the descendants of that node.
Types of nodes :-
• There are many types of nodes in the DOM document tree that specifies what kind of node it is.
Every Object in the DOM document tree has properties and methods defined by the Node host
object.
The following table lists the non method properties of Node object

Title:
Unit-3: Web technologies

Subject:
Web technology - Subject

Institute:
P.R.Engineering college

Unit-3: Web technologies P.R.Engineering college

Unit-3: Web technologies in Web technology - Subject uploaded at P.R.Engineering college

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