Javascript gets DOM node

There are many ways to obtain DOM nodes. You can obtain them based on the id attribute and tag name, or you can obtain child nodes, parent nodes, previous nodes, and next nodes.

This section explains how to obtain nodes based on the id attribute and label name of HTML tags.

getElementById() method

To obtain DOM nodes based on the id attribute of the HTML tag, please use the getElementById() method. This method returns a node object.

Syntax:
document.getElementById(id)
Among them, id is the id attribute of the HTML tag.

For example, the statement to obtain the node with id="demo" is:

The return value of this statement is [object HTMLDivElement] (element node object).

For example, get several typical element nodes:

     
我是
标签
 
我是
标签
 
我是
标签
  
   

Please see the following demonstration

getElementsByTagName( ) method

To obtain DOM nodes based on HTML tag names, please use the getElementsByTagName( ) method . This method returns the obtained element node as an array.
Syntax:
nodeObject.getElementsByTagName(tagName)
Among them, nodeObject is the element node and tagName is the name of the HTML tag.
Note: The getElementsByTagName() method can not only search all nodes in the entire HTML document, but also search the child nodes of a certain node. When using it, you must specify the search range, that is, specify nodeObject.
For example, to get all the

 
我是第 1 个
标签
 
我是第 2 个
标签
 
我是第 3 个
标签
 
我是第 4 个
标签 
我是第 5 个
标签
 
我是第 6 个
标签