JavaScript Dom Technology (i)

Source: Internet
Author: User

The first thing to understand is that the DOM is a tree based API for XML, which has many implementations (each language has its own implementation), and we discuss the implementation of the DOM in JavaScript or XHTML (HTML).

First, using the DOM

Consider an HTML file:


1. Access nodes:

Accessing HTML elements: var ohtml=document.documentelement;

element: var ohead=ohtml.firstchild;

Get the BODY element: Var obody=ohtml.lastchild; or Var obody=document.body;

You can also do the same thing through ChildNodes:

var ohead=ohtml.childnodes[0] or OHtml.childNodes.item (0);

var obody=ohtml.childnodes[1] or OHtml.childNodes.item (1);

To determine the relationship between nodes:


2. Detection node Type:

The node type is validated by the NodeType property of the node:

alert (Document.nodetype); Output 9

It should be noted that DOM-compatible browsers (take FF2.0 as an example) have constants such as Node.document_node, Node.element_node, and so on. The constant names and numerical tables are as follows:

ELEMENT_NODE                 1
ATTRIBUTE_NODE              2
TEXT_NODE                     3
ENTITY_NODE                   6
COMMENT_NODE               8
DOCUMENT_NODE              9
NOTATION_NODE               12

IE6 not supported, but you can customize a JS object node.

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