eslint/eslint · error · SyntaxError

Syntax error in selector "${selector}" at position ${err.loc

Error message

Syntax error in selector "${selector}" at position ${err.location.start.offset}: ${err.message}

What it means

Thrown by tryParseSelector when esquery fails to parse an AST selector string and the resulting error carries a location object (err.location.start.offset). The wrapper re-throws as a SyntaxError with the original selector, the 0-based offset of the failure, and esquery's message, chaining the original error as cause. Selectors that fail without a location are re-thrown unchanged.

Source

Thrown at lib/linter/esquery.js:272

	return null;
}

/**
 * Parses a raw selector string, and throws a useful error if parsing fails.
 * @param {string} selector The selector string to parse.
 * @returns {Object} An object (from esquery) describing the matching behavior of this selector
 * @throws {Error} An error if the selector is invalid
 */
function tryParseSelector(selector) {
	try {
		return esquery.parse(selector);
	} catch (err) {
		if (
			err.location &&
			err.location.start &&
			typeof err.location.start.offset === "number"
		) {
			throw new SyntaxError(
				`Syntax error in selector "${selector}" at position ${err.location.start.offset}: ${err.message}`,
				{
					cause: err,
				},
			);
		}
		throw err;
	}
}

/**
 * Parses a raw selector string, and returns the parsed selector along with specificity and type information.
 * @param {string} source A raw AST selector
 * @returns {ESQueryParsedSelector} A selector descriptor
 */
function parse(source) {
	if (selectorCache.has(source)) {
		return selectorCache.get(source);

View on GitHub (pinned to f131c034ad)

Solutions

Read the reported offset and fix the selector at that character position.
Validate selectors in isolation with require('esquery').parse(sel) during rule authoring.
Cross-check the selector against the esquery syntax reference supported by your ESLint version.
If building selectors dynamically, sanitize and unit-test the generated string.

Example fix

// before (malformed selector)
context.report({ node, message: 'x' });
// rule defined with selector: 'FunctionDeclaration >'

// after
// selector: 'FunctionDeclaration > BlockStatement'

Defensive patterns

Strategy: try-catch

Validate before calling

function isValidSelector(selector) {
  try { require('esquery').parse(selector.replace(/:exit$/u, '')); return true; } catch { return false; }
}

Type guard

function isParsableSelector(selector) { return typeof selector === 'string' && isValidSelector(selector); }

Try / catch

try { const parsed = require('esquery').parse(selector); } catch (err) {
  if (err.location && typeof err.location.start?.offset === 'number') {
    throw new SyntaxError(`Bad selector at offset ${err.location.start.offset}: ${err.message}`, { cause: err });
  }
  throw err;
}

Prevention

Unit-test custom rule selectors with esquery.parse during authoring.
Cross-check selector syntax against the esquery version bundled with your ESLint.
When building selectors dynamically, sanitize and validate the generated string before use.

When it happens

Trigger: Writing an invalid esquery selector in a rule's visitor: 'FunctionDeclaration >', ':not(', 'Identifier[', or any malformed CSS-like selector. The error surfaces when ESLint parses rule selectors at load/config time.

Common situations: Authoring a custom ESLint rule with a typo'd selector; using esquery syntax not supported by the bundled version; copy-paste from CSS docs introducing unsupported pseudo-classes; a dynamic selector built from user input that produced malformed output.

Related errors

AI-assisted analysis of eslint/eslint@f131c034ad (2026-08-03). Data as JSON: /data/errors/ce1db1c0c18ac80f.json. Report an issue: GitHub.