What is the difference between dom,dom level 1\2\3?

Dom

The Document Object model, or DOM, is the standard programming interface recommended by the Organization for the processing of extensible flag languages . The Document Object model dates back to the late 1990 's "browser Wars" between Microsoft and Netscape, which gave the browser powerful features in order to make life and death in JavaScript and JScript. Microsoft has added a number of proprietary things to Web technology, including VBScript, ActiveX, and Microsoft's own DHTML format, making it impossible for many Web pages to be displayed using non-Microsoft platforms and browsers. Dom is the masterpiece of the time.

According to the World Wide Web Dom specification, the DOM is an application programming interface (API) for HTML and XML, and the DOM maps the entire page into a file composed of hierarchical nodes. There are 1 levels, 2 levels, 3 levels and a total of 3.

Level 1 Dom

The 1-level DOM became a world wide proposal in October 1998, consisting of the DOM core and Dom HTML two modules. The DOM core maps an XML-based document structure, allowing access to and manipulation of any part of the document. Dom HTML extends the DOM core by adding HTML-specific objects and functions.

Level 2 DomGivenLevel 1 DOM targets only the mapping document structure, DOM Level 2 is more broad-oriented. By extending the original DOM,Level 2 DOM adds support for mouse and user interface events (DHTML long-term support for mouse and user interface events), scopes, traversal (repeating DOM documents), and cascading style sheets (CSS) through the object interface。 The core of Dom 1 is also extended toXML namespaces can be supported。

The Level 2 DOM introduces several new DOM modules to handleNewType of interface:

Dom View: Describes an interface that tracks various views of a document (before and after designing a document using CSS styles);

DOM Events: Describes the event interface;

DOM Style: Describes the interface that handles CSS-based styles;

DOM Traversal and scope: Describes the interface for traversing and manipulating document trees;

Level 3 Dom

The 3-level DOM further expands the DOM by introducing a unified way to load and save document and document validation methods, DOM3 contains a new module called "Dom Load and save", and the DOM core expands to support all XML1.0 content, including XML Infoset, XPath, and XML Base.

"Level 0" DOM

When you read a DOM-related material, you may encounter situations that refer to Level 0 DOM. It is important to note that there is no standard called Level 0 DOM, it is only a reference point in DOM history (Level 0 Dom is considered the earliest DHTML supported by Internet Explorer 4.0 and Netscape Navigator4.0).

What is the difference between dom,dom level 1\2\3?