XPathEvaluator: createExpression() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since July 2015.

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

Syntax

createExpression(expression)
createExpression(expression, resolver)

Parameters

expression: A string representing the XPath expression to be created.
resolver Optional: A Node, null, or any object implementing the lookupNamespaceURI method. Permits translation of all prefixes, including the xml namespace prefix, within the XPath expression into appropriate namespace URIs.

Return value

A 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 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 DOMException of type NAMESPACE_ERROR is raised.

Examples

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

HTML

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;