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How to get started with the DOM model? for this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a simpler and easier way.

To describe the concept of the DOM model, DOM is the abbreviation of DocumentObjectModel. Since the W3C established the DOM standard (W3CDOM), and after DOM is compatible with browsers, DOM has become more and more widely used in practice.

Overview of DOM Model

Since the W3C established the DOM standard (W3CDOM), and after DOM is compatible with browsers, DOM has been more and more widely used in practice. DOM is the abbreviation of DocumentObjectModel, and its Chinese name is document object model. Its main function is to establish a bridge between web page and Script or program language.

The properties, methods, and events that we can manipulate and create files are represented by and "objects" (for example, document represents the "file itself" object, table objects represent HTML table objects, and so on). These objects can be accessed by most browsers today in Script.

The DOM model is often used to interact with JavaScript, that is, programs are written in JavaScript, but DOM is used to access pages and their elements. The combination of the two is very close, it can even be said that if there is no DOM, we can not imagine using javascript, because we have to spend a lot of energy parsing an element of each node, DOM itself is designed as an independent programming language, with a consistent API access file structure expression; of course, in addition to JavaScript,DOM can also work with any programming language, such as JavaScript,DOM +, VB, VBS.

When interacting with JavaScript, the DOM model is mainly used to parse XML documents. When your application needs to constantly navigate, modify the document, or randomly access the entire document, we usually use DOM to parse.

When parsing with DOM, it builds a complete parsing tree in memory to achieve comprehensive and dynamic access to the entire XML document. In other words, its parsing is hierarchical, that is, all the elements in the html are parsed into hierarchical nodes on the tree, and then we can add, delete, modify and query these nodes, which is the most perfect summary of the role of the DOM model.

Unlike SAX, SAX is sequentially parsed, and SAX parsers provide better performance advantages than DOM, providing effective, low-level access to the content of XML documents.

The advantage of the SAX model is that it consumes less memory because the entire document does not need to be loaded into memory at once, which allows the SAX parser to parse documents that are larger than the system memory. In addition, you don't need to create objects for all nodes as you do in DOM. * SAX "push" model can be used in broadcast environment, which can register multiple ContentHandler at the same time and receive events in parallel, instead of processing one by one in a pipeline. But SAX has some disadvantages that make it less popular than DOM.

The use of the DOM model is very simple. You can access XML documents randomly, and since the entire tree is built in memory, you can modify these nodes through DOMAPI, such as adding a child node or modifying or deleting a node.

However, while the memory tree structure provides good navigation support, there are still some parsing strategy issues that need careful consideration. First of all, the entire XML document must be parsed at once, not only partially parsed; the second is efficiency, because it is expensive to load the entire document in memory and build a complete tree structure, especially when the document is very large. Typically, the capacity of the DOM tree is an order of magnitude larger than the document capacity, so it consumes a lot of memory; third, the general DOM node type has an advantage in interoperability, but it may not be * * for object type binding.

This is the answer to the introductory question on how to carry out the DOM model. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.

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