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


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


A DOMString representing the XPath expression to be parsed and evaluated.
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.



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


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


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


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.


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.


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


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


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



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

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