Playright supports different types of locators: CSS, XPath, internal.

They can mixed and matched by chaining the together.

Also, you can register custom selector engines that run right in the browser (Javascript).

There is no official documentation, since this is considered Playwright internal.

References:

• https://playwright.dev/docs/other-locators
• https://github.com/microsoft/playwright/blob/main/packages/playwright-core/src/client/locator.ts
• https://github.com/microsoft/playwright/blob/main/packages/playwright-core/src/utils/isomorphic/locatorUtils.ts