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Javascript getting started Article 7 js dom instance operations page 1/2

Source: Internet
Author: User
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Start with the method:
1. delete a node. RemoveChild ():
<Body>
<Div id = "cssrain">
<Div id = "a"> a </div>
<Div id = "B"> B </div>
<Div id = "c"> c </div>
</Div>
</Body>
<Script>
Var msg = document. getElementById ("cssrain ");
Var B = document. getElementById ("B ");
Msg. removeChild (B );
</Script>
If you do not know the parent node of the node to be deleted? You can use the parentNode attribute.
For example:
<Body>
<Div id = "cssrain">
<Div id = "a"> a </div>
<Div id = "B"> B </div>
<Div id = "c"> c </div>
</Div>
</Body>
<Script>
Var B = document. getElementById ("B ");
Var c = B. parentNode;
C. removeChild (B );
</Script>

2. Replace the node. RepalceChild ()
Element. repalceChild (newNode, oldNode); // The new node is a guest and must be served first .. The oldNode must be a subnode of the Element.
Example:
<Body>
<Div id = "cssrain">
<Div id = "a"> a </div>
<Div id = "B"> B </div>
<Div id = "c"> c </div>
</Div>
</Body>
<Script>
Var cssrain = document. getElementById ("cssrain ");
Var msg = document. getElementById ("B ");
Var para = document. createElement ("p ");
Cssrain. replaceChild (para, msg );
</Script>

3. Search for nodes
Compared with the above method, it is relatively simple to search for nodes.
Because many people have used it. (Remember that the first sentence I know about js is getElementById ();)
GetElementById ();
Returns an object with attributes such as nodeName, nodeType, parentNode, and ChildNodes.

GetElementsByTagName () is used to find all elements of a tag name.
Returns a set of objects that can be retrieved cyclically. Objects have attributes such as nodeName, nodeType, parentNode, and ChildNodes.
Example:
Var ps = document. getElementsByTagName ("p ");
For (var I = 0; I <ps. length; I ++ ){
Ps [I]. setAttribute ("title", "hello ");
// You can also use: ps. item (I). setAttribute ("title", "hello ");
}

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