microsoft/playwright · error · Error

"is" engine expects non-empty selector list

Error message

"is" engine expects non-empty selector list

What it means

Error ""is" engine expects non-empty selector list" thrown in microsoft/playwright.

Source

Thrown at packages/injected/src/selectorEvaluator.ts:387

        }
      }
      query(context.scope);
      return result;
    });
  }

  private _getEngine(name: string): SelectorEngine {
    const engine = this._engines.get(name);
    if (!engine)
      throw new Error(`Unknown selector engine "${name}"`);
    return engine;
  }
}

const isEngine: SelectorEngine = {
  matches(element: Element, args: (string | number | Selector)[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
    if (args.length === 0)
      throw new Error(`"is" engine expects non-empty selector list`);
    return args.some(selector => evaluator.matches(element, selector, context));
  },

  query(context: QueryContext, args: (string | number | Selector)[], evaluator: SelectorEvaluator): Element[] {
    if (args.length === 0)
      throw new Error(`"is" engine expects non-empty selector list`);
    let elements: Element[] = [];
    for (const arg of args)
      elements = elements.concat(evaluator.query(context, arg));
    return args.length === 1 ? elements : sortInDOMOrder(elements);
  },
};

const hasEngine: SelectorEngine = {
  matches(element: Element, args: (string | number | Selector)[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
    if (args.length === 0)
      throw new Error(`"has" engine expects non-empty selector list`);
    return evaluator.query({ ...context, scope: element }, args).length > 0;

View on GitHub (pinned to c8fc3bf8d3)

When it happens

Trigger: Thrown at packages/injected/src/selectorEvaluator.ts:387 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/playwright@c8fc3bf8d3 (2026-08-12). Data as JSON: /api/errors/2e4449310f8be50a. Report an issue: GitHub.