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API Reference / Telerik.WinForms.Documents.FormatProviders.Html.Parsing.Dom / IElement
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IElement

Interface

The 

Element
interface represents an element in an HTML or XML document. Elements may have attributes associated with them; since the 
Element
interface inherits from 
Node
, the generic 
Node
interface attribute 
attributes
may be used to retrieve the set of all attributes for an element. There are methods on the 
Element
interface to retrieve either an 
Attr
object by name or an attribute value by name. In XML, where an attribute value may contain entity references, an 
Attr
object should be retrieved to examine the possibly fairly complex sub-tree representing the attribute value. On the other hand, in HTML, where all attributes have simple string values, methods to directly access an attribute value can safely be used as a convenience.In DOM Level 2, the method 
normalize
is inherited from the 
Node
interface where it was moved.

See also the Document Object Model (DOM) Level 2 Core Specification.

Definition

Properties

TagName

The name of the element. For example, in: 

 <elementExample
id="demo"> ... </elementExample> , 
tagName
has the value 
"elementExample"
. Note that this is case-preserving in XML, as are all of the operations of the DOM. The HTML DOM returns the 
tagName
of an HTML element in the canonical uppercase form, regardless of the case in the source HTML document.

C#
string TagName { get; }

Methods

GetAttribute(string)

Retrieves an attribute value by name.

C#
string GetAttribute(string name)
Parameters:namestring

The name of the attribute to retrieve.

Returns:

string

The 

Attr
value as a string, or the empty string if that attribute does not have a specified or default value.

GetAttributeNode(string)

Retrieves an attribute node by name.
To retrieve an attribute node by qualified name and namespace URI, use the 

getAttributeNodeNS
method.

C#
IAttr GetAttributeNode(string name)
Parameters:namestring

The name (

nodeName
) of the attribute to retrieve.

Returns:

IAttr

The 

Attr
node with the specified name (
nodeName
) or 
null
if there is no such attribute.

GetAttributeNodeNS(string, string)

Retrieves an 

Attr
node by local name and namespace URI. HTML-only DOM implementations do not need to implement this method.

C#
IAttr GetAttributeNodeNS(string namespaceUri, string localName)
Parameters:namespaceUristring

The namespace URI of the attribute to retrieve.

localNamestring

The local name of the attribute to retrieve.

Returns:

IAttr

The 

Attr
node with the specified attribute local name and namespace URI or 
null
if there is no such attribute.

GetAttributeNS(string, string)

Retrieves an attribute value by local name and namespace URI. HTML-only DOM implementations do not need to implement this method.

C#
string GetAttributeNS(string namespaceUri, string localName)
Parameters:namespaceUristring

The namespace URI of the attribute to retrieve.

localNamestring

The local name of the attribute to retrieve.

Returns:

string

The 

Attr
value as a string, or the empty string if that attribute does not have a specified or default value.

GetElementsByTagName(string)

Returns a 

NodeList
of all descendant 
Elements
with a given tag name, in the order in which they are encountered in a preorder traversal of this 
Element
tree.

C#
INodeList GetElementsByTagName(string name)
Parameters:namestring

The name of the tag to match on. The special value "*" matches all tags.

Returns:

INodeList

A list of matching 

Element
nodes.

GetElementsByTagNameNS(string, string)

Returns a 

NodeList
of all the descendant 
Elements
with a given local name and namespace URI in the order in which they are encountered in a preorder traversal of this 
Element
tree.
HTML-only DOM implementations do not need to implement this method.

C#
INodeList GetElementsByTagNameNS(string namespaceUri, string localName)
Parameters:namespaceUristring

The namespace URI of the elements to match on. The special value "*" matches all namespaces.

localNamestring

The local name of the elements to match on. The special value "*" matches all local names.

Returns:

INodeList

A new 

NodeList
object containing all the matched 
Elements
.

HasAttribute(string)

Returns 

true
when an attribute with a given name is specified on this element or has a default value, 
false
otherwise.

C#
bool HasAttribute(string name)
Parameters:namestring

The name of the attribute to look for.

bool

csharp
true
    specified on this element or has a default value, <pre><code class="lang-csharp">false</code></pre>
    otherwise.

HasAttributeNS(string, string)

Returns 

true
when an attribute with a given local name and namespace URI is specified on this element or has a default value, 
false
otherwise. HTML-only DOM implementations do not need to implement this method.

C#
bool HasAttributeNS(string namespaceUri, string localName)
Parameters:namespaceUristring

The namespace URI of the attribute to look for.

localNamestring

The local name of the attribute to look for.

bool

csharp
true
    and namespace URI is specified or has a default value on this 
    element, <pre><code class="lang-csharp">false</code></pre> otherwise.

RemoveAttribute(string)

Removes an attribute by name. If the removed attribute is known to have a default value, an attribute immediately appears containing the default value as well as the corresponding namespace URI, local name, and prefix when applicable.
To remove an attribute by local name and namespace URI, use the 

removeAttributeNS
method.

C#
void RemoveAttribute(string name)
Parameters:namestring

The name of the attribute to remove.

Exceptions: DomException

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

RemoveAttributeNode(IAttr)

Removes the specified attribute node. If the removed 

Attr
has a default value it is immediately replaced. The replacing attribute has the same namespace URI and local name, as well as the original prefix, when applicable.

C#
IAttr RemoveAttributeNode(IAttr oldAttr)
Parameters:oldAttrIAttr

The 

Attr
node to remove from the attribute list.

Returns:

IAttr

The 

Attr
node that was removed.

Exceptions: DomException

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
NOT_FOUND_ERR: Raised if 

oldAttr
is not an attribute of the element.

RemoveAttributeNS(string, string)

Removes an attribute by local name and namespace URI. If the removed attribute has a default value it is immediately replaced. The replacing attribute has the same namespace URI and local name, as well as the original prefix.
HTML-only DOM implementations do not need to implement this method.

C#
void RemoveAttributeNS(string namespaceUri, string localName)
Parameters:namespaceUristring

The namespace URI of the attribute to remove.

localNamestring

The local name of the attribute to remove.

Exceptions: DomException

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

SetAttribute(string, string)

Adds a new attribute. If an attribute with that name is already present in the element, its value is changed to be that of the value parameter. This value is a simple string; it is not parsed as it is being set. So any markup (such as syntax to be recognized as an entity reference) is treated as literal text, and needs to be appropriately escaped by the implementation when it is written out. In order to assign an attribute value that contains entity references, the user must create an 

Attr
node plus any 
Text
and 
EntityReference
nodes, build the appropriate subtree, and use 
setAttributeNode
to assign it as the value of an attribute.
To set an attribute with a qualified name and namespace URI, use the 
setAttributeNS
method.

C#
void SetAttribute(string name, string value)
Parameters:namestring

The name of the attribute to create or alter.

valuestring

Value to set in string form.

Exceptions: DomException

INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

SetAttributeNode(IAttr)

Adds a new attribute node. If an attribute with that name ( 

nodeName
) is already present in the element, it is replaced by the new one.
To add a new attribute node with a qualified name and namespace URI, use the 
setAttributeNodeNS
method.

C#
IAttr SetAttributeNode(IAttr newAttr)
Parameters:newAttrIAttr

The 

Attr
node to add to the attribute list.

Returns:

IAttr

If the 

newAttr
attribute replaces an existing attribute, the replaced 
Attr
node is returned, otherwise 
null
is returned.

Exceptions: DomException

WRONG_DOCUMENT_ERR: Raised if 

newAttr
was created from a different document than the one that created the element.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
INUSE_ATTRIBUTE_ERR: Raised if 
newAttr
is already an attribute of another 
Element
object. The DOM user must explicitly clone 
Attr
nodes to re-use them in other elements.

SetAttributeNodeNS(IAttr)

Adds a new attribute. If an attribute with that local name and that namespace URI is already present in the element, it is replaced by the new one.
HTML-only DOM implementations do not need to implement this method.

C#
IAttr SetAttributeNodeNS(IAttr newAttr)
Parameters:newAttrIAttr

The 

Attr
node to add to the attribute list.

Returns:

IAttr

If the 

newAttr
attribute replaces an existing attribute with the same local name and namespace URI, the replaced 
Attr
node is returned, otherwise 
null
is returned.

Exceptions: DomException

WRONG_DOCUMENT_ERR: Raised if 

newAttr
was created from a different document than the one that created the element.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
INUSE_ATTRIBUTE_ERR: Raised if 
newAttr
is already an attribute of another 
Element
object. The DOM user must explicitly clone 
Attr
nodes to re-use them in other elements.

SetAttributeNS(string, string, string)

Adds a new attribute. If an attribute with the same local name and namespace URI is already present on the element, its prefix is changed to be the prefix part of the 

qualifiedName
, and its value is changed to be the 
value
parameter. This value is a simple string; it is not parsed as it is being set. So any markup (such as syntax to be recognized as an entity reference) is treated as literal text, and needs to be appropriately escaped by the implementation when it is written out. In order to assign an attribute value that contains entity references, the user must create an 
Attr
node plus any 
Text
and 
EntityReference
nodes, build the appropriate subtree, and use 
setAttributeNodeNS
or 
setAttributeNode
to assign it as the value of an attribute.
HTML-only DOM implementations do not need to implement this method.

C#
void SetAttributeNS(string namespaceUri, string qualifiedName, string value)
Parameters:namespaceUristring

The namespace URI of the attribute to create or alter.

qualifiedNamestring

The qualified name of the attribute to create or alter.

valuestring

The value to set in string form.

DomException

INVALID_CHARACTER_ERR: Raised if the specified qualified name contains an illegal character.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
NAMESPACE_ERR: Raised if the 

qualifiedName
is malformed, if the 
qualifiedName
has a prefix and the

csharp
namespaceURI
csharp
null
csharp
qualifiedName
csharp
namespaceURI

http://www.w3.org/XML/1998/namespace", or if the

csharp
qualifiedName
csharp
namespaceURI

http://www.w3.org/2000/xmlns/".

In this article
DefinitionPropertiesTagNameMethodsGetAttribute(string)GetAttributeNode(string)GetAttributeNodeNS(string, string)GetAttributeNS(string, string)GetElementsByTagName(string)GetElementsByTagNameNS(string, string)HasAttribute(string)HasAttributeNS(string, string)RemoveAttribute(string)RemoveAttributeNode(IAttr)RemoveAttributeNS(string, string)SetAttribute(string, string)SetAttributeNode(IAttr)SetAttributeNodeNS(IAttr)SetAttributeNS(string, string, string)
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