Implementation:Microsoft Playwright LocatorParser

Overview

LocatorParser parses locator strings from various programming languages (JavaScript, Python, Java, C#) back into Playwright selectors, enabling the codegen and inspector tools to work with human-readable locator expressions.

Description

The parseLocator function takes a locator expression written in any supported language and converts it back into a Playwright internal selector string. It handles:

• Template string parsing with escape sequence support
• Regular expression literal parsing
• Language-specific method names (e.g., getByRole vs get_by_role)
• Role enum values (e.g., AriaRole.Button to 'button')
• Quote style detection for round-trip fidelity

The parser uses a template-based approach where string literals are extracted and replaced with placeholders, then the template is matched against known locator patterns.

Usage

Used by the codegen/inspector tool to parse locator expressions entered by users.

Code Reference

Source Location

packages/playwright-core/src/utils/isomorphic/locatorParser.ts (248 lines)

Function Signature

function parseLocator(locator: string, testIdAttributeName: string): {
  selector: string;
  preferredQuote: Quote | undefined;
};

Import

import { parseLocator } from '../utils/isomorphic/locatorParser';

I/O Contract

Inputs

• locator: string -- locator expression in any supported language
• testIdAttributeName: string -- the configured test ID attribute

Outputs

• selector: string -- internal Playwright selector string
• preferredQuote -- the quote style used in the original expression

Supported Patterns

• getByRole, getByText, getByLabel, getByPlaceholder
• getByAltText, getByTitle, getByTestId
• locator with CSS selectors
• Chained locators with .filter(), .nth(), etc.

Related Pages

• Microsoft_Playwright_CssParser -- CSS selector parsing
• Microsoft_Playwright_Server_Selectors -- Selector engine registry
• Microsoft_Playwright_StringUtils -- String escaping utilities