| Package | dom.xpath |
| Interface | public interface XPathEvaluator |
| Implementors | HTMLDocument |
| Introduced in: | DOM 3 XPath |
Evaluation of expressions with specialized extension functions or variables may not work in all implementations and is, therefore, not portable. XPathEvaluator implementations may be available from other sources that could provide specific support for specialized extension functions or variables as would be defined by other specifications.
See also
| Method | Defined By | ||
|---|---|---|---|
Creates a parsed XPath expression with resolved namespaces. | XPathEvaluator | ||
Adapts any DOM node to resolve namespaces so that an XPath expression can be easily evaluated
relative to the context of the node where it appeared within the document. | XPathEvaluator | ||
DOM 3 XPath evaluate(expression:DOMString, contextNode:Node, resolver:XPathNSResolver, type:Number, result:DOMObject):DOMObject
Evaluates an XPath expression string and returns a result of the specified type if possible. | XPathEvaluator | ||
| DOM 3 XPath createExpression | () | method |
public function createExpression(expression:DOMString, resolver:XPathNSResolver):XPathExpression| Introduced in: | DOM 3 XPath |
Creates a parsed XPath expression with resolved namespaces. This is useful when an expression will be reused in an application since it makes it possible to compile the expression string into a more efficient internal form and preresolve all namespace prefixes which occur within the expression.
Note (Mozilla): Prior to Firefox 3, you could call this method on documents other than the one you planned to run the XPath against. Under Firefox 3, you must call it on the same document.
Parameters
expression:DOMString — The XPath expression string to be parsed.
| |
resolver:XPathNSResolver — The resolver permits translation of all prefixes, including the xml
namespace prefix, within the XPath expression into appropriate namespace URIs. If this
is specified as null, any namespace prefix within the expression will result in
DOMException being thrown with the code NAMESPACE_ERR.
|
XPathExpression — The compiled form of the XPath expression.
|
XPathException — INVALID_EXPRESSION_ERR: Raised if the expression is
not legal according to the rules of the XPathEvaluator.
| |
EventException — NAMESPACE_ERR: Raised if the expression contains
namespace prefixes which cannot be resolved by the specified XPathNSResolver.
|
See also
| DOM 3 XPath createNSResolver | () | method |
public function createNSResolver(nodeResolver:Node):XPathNSResolver| Introduced in: | DOM 3 XPath |
Adapts any DOM node to resolve namespaces so that an XPath expression can be easily evaluated relative to the context of the node where it appeared within the document. This adapter works like the DOM Level 3 method lookupNamespaceURI on nodes in resolving the namespaceURI from a given prefix using the current information available in the node's hierarchy at the time lookupNamespaceURI is called. also correctly resolving the implicit xml prefix.
Note: XPath defines QNames without prefix to match only elements in the
null namespace. There is no way in XPath to pick up the default namespace as applied to a regular
element reference (e.g., p[&64;id='_myid'] for xmlns='http://www.w3.org/1999/xhtml').
To match default elements in a non-null namespace, you either have to refer to a particular element using
a form such as *
Parameters
nodeResolver:Node — The node to be used as a context for namespace resolution.
|
XPathNSResolver — XPathNSResolver which resolves namespaces with respect to the definitions in scope for a specified node.
|
See also
| DOM 3 XPath evaluate | () | method |
public function evaluate(expression:DOMString, contextNode:Node, resolver:XPathNSResolver, type:Number, result:DOMObject):DOMObject| Introduced in: | DOM 3 XPath |
Evaluates an XPath expression string and returns a result of the specified type if possible.
Parameters
expression:DOMString — The XPath expression string to be parsed and evaluated.
| |
contextNode:Node — The context is context node for the evaluation of this XPath expression.
If the XPathEvaluator was obtained by casting the Document then this must be owned by the same
document and must be a Document, Element, Attribute, Text, CDATASection, Comment,
ProcessingInstruction, or XPathNamespace node. If the context node is a Text or a CDATASection,
then the context is interpreted as the whole logical text node as seen by XPath, unless the node
is empty in which case it may not serve as the XPath context.
| |
resolver:XPathNSResolver — The resolver permits translation of all prefixes, including the xml namespace
prefix, within the XPath expression into appropriate namespace URIs. If this is specified as null,
any namespace prefix within the expression will result in DOMException being thrown with the
code NAMESPACE_ERR.
| |
type:Number — If a specific type is specified, then the result will be returned as the
corresponding type. For XPath 1.0 results, this must be one of the codes of the XPathResult interface.
| |
result:DOMObject — The result specifies a specific result object which may be reused and returned by
this method. If this is specified as nullor the implementation does not reuse the specified result,
a new result object will be constructed and returned. For XPath 1.0 results, this object will be
of type XPathResult.
|
DOMObject — The result of the evaluation of the XPath expression. For XPath 1.0 results, this object
will be of type XPathResult.
|
XPathException — INVALID_EXPRESSION_ERR: Raised if the expression is not legal according to the rules of the XPathEvaluator.
| |
XPathException — TYPE_ERR: Raised if the result cannot be converted to return the specified type.
| |
EventException — NAMESPACE_ERR: Raised if the expression contains namespace prefixes which cannot be resolved by the specified XPathNSResolver.
| |
EventException — WRONG_DOCUMENT_ERR: The Node is from a document that is not supported by the XPathEvaluator that created this XPathExpression.
| |
EventException — NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath context node or the request type is not permitted by this XPathExpression.
|
See also
var headings = document.evaluate("//h2", document, null, XPathResult.ANY_TYPE, null);
/* Search the document for all h2 elements.
* The result will likely be an unordered node iterator. */
var thisHeading = headings.iterateNext();
var alertText = "Level 2 headings in this document are:\n";
while (thisHeading) {
alertText += thisHeading.textContent + "\n";
thisHeading = headings.iterateNext();
}
alert(alertText); // Alerts the text of all h2 elements