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JavaScript first Knowledge (a): Acquiring nodes

Source: Internet
Author: User
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JAVASCRIOPT Dom has three main nodes: element node, attribute node, text node.

The three main methods of acquiring ELEMENT nodes are:

1.document.getelementbyid (); This method gets the node based on the unique ID value of the node.

such as <li id = "Hamigua" > Cantaloupe </li>,document.getelementbyid ("Hamigua");

2.document.getelementbytagname (); This method gets the node based on the label name of the node.

such as <li></li> tags, document.getelementbytagname ("Li");

3.document.getelementbyname (); This method gets the node based on the Name property of the node.

such as <input type = "text" name = "N_hamigua" value = "cantaloupe"/>,document.getelementbyname ("N_hamigua");

However, this method can only get a node with the name attribute, such as <li name = "Li_hamigua" ></li>,document.getelementbyname (Li_hamigua); You should pay attention to this problem when using.

Both the attribute node and the text node need to be fetched to the element node before acquiring it.

Attribute node: <input type = "text" id = "Input_hamihua" value = "Value_hamigua"/>;d Ocument.getelementbyid ("Input_hamigua") . GetAttributeNode ("value");

This allows you to get to the Value property of the input tag, which is the property of "Value_hamigua".

Text node: <li id = "Li_hamigua" > Cantaloupe </li>;d ocument.getelementbyid ("Li_hamigua"). FirstChild;

This allows you to get the text node of the input tag, which is the text value of "cantaloupe".

Explain the difference between the three nodes here:

① ELEMENT nodes: Similar to nodes such as <body></body>, <li></li>, <input/>.

② attribute node: Similar to <input type= "text" name= "text"/> "name= ' text" in such a node.

③ text node: a node similar to "HelloWorld" in <li>HelloWorld</li>.

JavaScript first Knowledge (a): Acquiring nodes

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