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I. Creating, inserting, and deleting elements
(1) Creating DOM elements
CreateElement (sign) Create a node
AppendChild (node) append one node
Example: inserting LI for UL
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> Untitled Document </title>
<script>
Window.onload = function ()
{
var Obtn=document.getelementbyid (' btn1 ');
var Oul=document.getelementbyid (' Ul1 ');
var Otxt=document.getelementbyid (' Txt1 ');
Obtn.onclick = function ()
{
var oli=document.createelement (' Li ');/* Create a good Li, the system does not know where to put it, we need to set the * *
Oli.innerhtml=otxt.value;
Parent,. appendchild (sub-node);
Oul.appendchild (oLi);/*oli added to oul*/as a child node
};
};
</script>
<body>
<input id= "Txt1" ytpe= "text"/>
<input id= "btn1" type= "button" value= "Create Li"/>
<ul id= "UL1" >
</ul>
</body>
(2) Inserting elements
InsertBefore (node, original node) in existing element money insertion
Example: Reverse Insert Li
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> Untitled Document </title>
<script>
Window.onload = function ()
{
var Obtn=document.getelementbyid (' btn1 ');
var Oul=document.getelementbyid (' Ul1 ');
var Otxt=document.getelementbyid (' Txt1 ');
Obtn.onclick = function ()
{
var oli=document.createelement (' Li ');/* Create a good Li, the system does not know where to put it, we need to set the * *
var ali=oul.getelementsbytagname (' Li ');
Oli.innerhtml=otxt.value;
Parent,. appendchild (sub-node);
Oul.appendchild (oLi);/*oli added to oul*/as a child node
This code is designed to be compatible with IE
if (ali.length>0)
{
Oul.insertbefore (oli,ali[0]) */* insert before NO. 0 Li */
}
Else
{
Oul.appendchild (oLi); * * Append a node directly using appendchild if there is no previous Li */
}
};
};
</script>
<body>
<input id= "Txt1" ytpe= "text"/>
<input id= "btn1" type= "button" value= "Create Li"/>
<ul id= "UL1" >
</ul>
</body>
(3) Removing DOM elements
RemoveChild (node) Delete a node
Example: Remove Li
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> Delete Elements </title>
<script>
Window.onload = function ()
{
var aa=document.getelementsbytagname (' a ');
var Oul=document.getelementbyid (' Ul1 ');
for (Var i=0;i<aa.length;i++)
{
Aa[i].onclick = function ()
{
Oul.removechild (This.parentnode);
};
}
};
</script>
<body>
<ul id= "UL1" >
<li>aaaaa<a href= "javascript:;" > Delete </a></li>
<li>bbbbbb<a href= "javascript:;" > Delete </a></li>
<li>cccccc<a href= "javascript:;" > Delete </a></li>
<li>dddddd<a href= "javascript:;" > Delete </a></li>
</ul>
</body>
Second, document fragmentation
(1) Document fragmentation can improve the performance of the DOM (theoretically), but only in the low-level browser, if in the advanced browser, this method may lead to performance is not improved but decreased.
For example, to insert 10,000 Li tags, if there is no document fragmentation, you must insert one and then render the page once, insert the full part will be rendered 10,000 times, too lossy performance. With document fragmentation, you can first put all the changes you need into the document fragment and render again.
(2) Document fragmentation principle
(3) Document.createdocumentfragment ()
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> Document Fragmentation 2</title>
<script>
Window.onload = function ()
{
var Oul=document.getelementbyid (' Ul1 ');
var ofrag=document.createdocumentfragment ();/* Create document Fragment */
for (Var i=0;i<10000;i++)
{
var oli=document.createelement (' Li ');
Ofrag.appendchild (oLi) */* directly into the document fragment * *
}
Oul.appendchild (Ofrag);/* Load the document fragment one at a time into the Oul */
};
</script>
<body>
<ul id= "UL1" >
</ul>
</body>
"JS Learning notes" DOM action App-Create, insert, and delete elements; document fragmentation
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