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What is node

藏色散人

Release： 2021-12-07 15:10:29

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Node has three meanings: 1. Refers to a network node, which is mainly responsible for sending, receiving and forwarding information in the network; 2. Refers to a node in an XML document. Different types of nodes in the document tree are represented by specific Node sub-elements. Interface representation; 3. Refers to Node.js, a js running environment based on Chrome V8 engine.

What is node

The operating environment of this article: Windows 7 system, nodejs version 10.16.2, Dell G3 computer.

What is node?

node has many meanings:

1. Network node

A node refers to a computer or other device and a Have an independent address and be connected to a network capable of transmitting or receiving data. Nodes can be workstations, clients, network users, or personal computers, as well as servers, printers, and other network-connected devices. Every workstation, server, terminal device, and network device that has its own unique network address is a network node. Network nodes are mainly responsible for sending, receiving and forwarding information in the network. Network nodes are the interface between computers and networks. Computers send information to other computers through network nodes, and identify and receive information sent by other computers. In large-scale networks, network nodes are generally played by a processor or communication controller. At this time, the network node also has the functions of storage and forwarding and path selection. The network adapter used in the LAN is also a network node.

The two endpoints of the network cable are nodes, and the connection relationship between network cables is established through the nodes. In reality, there are many nodes in the network, such as street intersections, river junctions, telephone transmission points, gates in the power grid, water gates in the river network, etc. Nodes can be represented as vertices, endpoints, and are associated with network lines.

Node Node, node, network node can be a workstation, client, network user or personal computer, or it can also be a server, printer and other network-connected devices.

2. Nodes in XML documents

In the DOM (Document Object Model), the hierarchical structure of the HTML document is represented as a tree structure. The nodes of the tree represent various contents in the document. The tree representation of an HTML document mainly consists of nodes representing elements or tags (such as and ) and nodes identifying text strings. HTML documents also contain nodes that represent HTML comments. Consider the following simple HTML document:

<html>
<head>
<title>a document</title>
</head>
<body>
<h1>is html document</h1>
<p>this is a<i>documnet</i>
</body></html>

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If you are not familiar with the structure of properties in computer programming, it will be helpful to know some terminology that these properties have borrowed from their family tree. The node directly above a node is its parent. Nodes directly below a node are children of that node. Nodes located at the same level and with the same parent node are siblings. The set of nodes at the next level of a node are the descendants of that node. A node's parent node, grandparent node, and all other nodes above it are the ancestors of that node.

The DOM attribute structure shown in the figure is a tree of various types of NODE objects. The NODE interface defines properties and methods for convenience and operation trees. The childNodes property of the NODE object will return a list of child nodes, and the firstChild, lastChild, nextSibling, previousSibling, and parentNode properties provide methods for traversing the tree. The appendChild(), removeChild(), replaceChild, and insertBefore() methods allow you to add nodes to or remove nodes from the document tree.

Types of nodes

Different types of nodes in the document tree are represented by specific Node sub-interfaces. Each Node object has nodeType properties, which specify the type of node. For example, if a node's nodeType attribute is equal to the constant attributes, these attributes specify the type of the node. For example, if the nodeType attribute of a node is equal to the constant node.ELEMENT_NODE, you know that the Node object is still an Element object, and you can use all the methods and properties defined by the Element interface on it.

3. Node.js

Node.js was released in May 2009 and developed by Ryan Dahl. It is a JavaScript running environment based on the Chrome V8 engine. Use It provides an event-driven, non-blocking I/O model that allows JavaScript to run on the server-side development platform. It makes JavaScript a scripting language on par with server-side languages such as PHP, Python, Perl, and Ruby.

Recommended learning: "nodejs video tutorial"

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