XPathEvaluator: createExpression() method

{{APIRef("DOM")}}

This method compiles an {{domxref("XPathExpression")}} which can then be used for (repeated) evaluations of the {{Glossary("XPath")}} expression.

Syntax

createExpression(expression)
createExpression(expression, resolver)

Parameters

• expression
  • : A string representing the XPath expression to be created.
• resolver {{optional_inline}}
  • : A {{domxref("Node")}}, null, or any object implementing the {{domxref("Node/lookupNamespaceURI", "lookupNamespaceURI")}} method. Permits translation of all prefixes, including the xml namespace prefix, within the XPath expression into appropriate namespace URIs.

Return value

A {{domxref("XPathExpression")}} representing the compiled form of the XPath expression.

Exceptions

INVALID_EXPRESSION_ERR

If the expression is not legal according to the rules of the XPathEvaluator, a {{domxref("DOMException")}} of type INVALID_EXPRESSION_ERR is raised.

NAMESPACE_ERR

If the expression contains namespace prefixes which cannot be resolved by the specified XPathNSResolver, a {{domxref("DOMException")}} of type NAMESPACE_ERROR is raised.

Examples

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

const xpath = "//div";
const evaluator = new XPathEvaluator();
const expression = evaluator.createExpression(xpath);
const result = expression.evaluate(
  document,
  XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
);
document.querySelector("output").textContent = result.snapshotLength;

Result

{{EmbedLiveSample('Examples')}}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{DOMxRef("Document.createExpression()")}}
• {{DOMxRef("XPathExpression")}}