{"record":{"id":"d035dc68f4c9b96c","repo":"microsoft/playwright","slug":"nth-match-engine-expects-a-one-based-index-as-th","errorCode":null,"errorMessage":"\"nth-match\" engine expects a one-based index as the last argument","messagePattern":"\"nth-match\" engine expects a one-based index as the last argument","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/injected/src/selectorEvaluator.ts","lineNumber":531,"sourceCode":"      if (args.length < 1 + (maxDistance === undefined ? 0 : 1))\n        throw new Error(`\"${name}\" engine expects a selector list and optional maximum distance in pixels`);\n      const inner = evaluator.query(context, queryArgs);\n      const score = layoutSelectorScore(name, element, inner, maxDistance);\n      if (score === undefined)\n        return false;\n      (evaluator as SelectorEvaluatorImpl)._markScore(element, score);\n      return true;\n    }\n  };\n}\n\nconst nthMatchEngine: SelectorEngine = {\n  query(context: QueryContext, args: (string | number | Selector)[], evaluator: SelectorEvaluator): Element[] {\n    let index = args[args.length - 1];\n    if (args.length < 2)\n      throw new Error(`\"nth-match\" engine expects non-empty selector list and an index argument`);\n    if (typeof index !== 'number' || index < 1)\n      throw new Error(`\"nth-match\" engine expects a one-based index as the last argument`);\n    const elements = isEngine.query!(context, args.slice(0, args.length - 1), evaluator);\n    index--;  // one-based\n    return index < elements.length ? [elements[index]] : [];\n  },\n};\n\nfunction parentElementOrShadowHostInContext(element: Element, context: QueryContext): Element | undefined {\n  if (element === context.scope)\n    return;\n  if (!context.pierceShadow)\n    return element.parentElement || undefined;\n  return parentElementOrShadowHost(element);\n}\n\nfunction previousSiblingInContext(element: Element, context: QueryContext): Element | undefined {\n  if (element === context.scope)\n    return;\n  return element.previousElementSibling || undefined;","sourceCodeStart":513,"sourceCodeEnd":549,"githubUrl":"https://github.com/microsoft/playwright/blob/c8fc3bf8d31542d59b4d4d9eaab1df93ff541dc6/packages/injected/src/selectorEvaluator.ts#L513-L549","documentation":"Error \"\"nth-match\" engine expects a one-based index as the last argument\" thrown in microsoft/playwright.","triggerScenarios":"Thrown at packages/injected/src/selectorEvaluator.ts:531 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"c8fc3bf8d31542d59b4d4d9eaab1df93ff541dc6","analyzedAt":"2026-08-12T07:26:36.950Z","schemaVersion":2},"datasetVersion":"2026-08-12T13:17:24.610Z"}