XPathEvaluator.evaluate()

Vous lisez la version anglaise de ce contenu car il n’existe pas encore de traduction dans cette langue. Aidez-nous à traduire cet article !

The evaluate() method of the XPathEvaluator interface executes an XPath expression on the given node or document and returns an XPathResult.

Syntax

XPathResult XPathEvaluator.evaluate(expression, contextNode, resolver, type, result);

Parameters

expression
A DOMString representing the XPath expression to be parsed and evaluated.
contextNode
A Node representing the context to use for evaluating the expression.
resolver Optional
Permits translation of all prefixes, including the xml namespace prefix, within the XPath expression into appropriate namespace URIs.
type Optional
Specifies the type of result to be returned by evaluating the expression. This must be one of the XPathResult.Constants.
result Optional
Allows to specify a result object which may be reused and returned by this method. If this is specified as null or the implementation does not reuse the specified result, a new result object will be returned.

Return value

An XPathResult object representing the result of evaluating the XPath expression.

Exceptions

INVALID_EXPRESSION_ERR

If the expression is not legal according to the rules of the XPathEvaluator, an XPathException of type INVALID_EXPRESSION_ERR is raised.

TYPE_ERR

In case result cannot be converted to the specified type, an XPathException of type TYPE_ERR is raised.

NAMESPACE_ERR

If the expression contains namespace prefixes which cannot be resolved by the specified XPathNSResolver, a DOMException of type NAMESPACE_ERROR is raised.

WRONG_DOCUMENT_ERR

If the provided context node is from a document that is not supported by the XPathEvaluator, a DOMException of type WRONG_DOCUMENT_ERR is raised.

NOT_SUPPORTED_ERR

If the provided context node is not a type permitted as an XPath context node or the request type is not permitted by the XPathEvaluator, a DOMException of type NOT_SUPPORTED_ERR is raised.

Example

The following example shows the use of the evaluate() method.

HTML

<div>XPath example</div>
<div>Number of &lt;div&gt;s: <output></output></div>

JavaScript

var evaluator = new XPathEvaluator();
var result = evaluator.evaluate("//div", document, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE);
document.querySelector("output").textContent = result.snapshotLength;

Result

Specifications

Specification Status Comment
Document Object Model (DOM) Level 3 XPath Specification
The definition of 'XPathEvaluator.evaluate()' in that specification.
Recommendation Initial definition

Browser compatibility

No compatibility data found. Please contribute data for "api.XPathEvaluator.evaluate()" (depth: 1) to the MDN compatibility data repository.