locators

Locators are mechanisms used to identify and access a target element or resource within a system. In web development, testing, and UI automation, a locator specifies how to find a particular element in a document object model (DOM) or in a graphical interface.

Common locator strategies in web contexts include IDs, names, CSS selectors, XPath expressions, class names, tag names, link texts, and data attributes such as data-testid or data-test. Each strategy has trade-offs in terms of uniqueness, stability, and performance.

Best practices emphasize stability and maintainability. Prefer unique IDs when available; use CSS selectors for fast, stable matching; reserve XPath for complex navigations but avoid brittle paths that depend on exact DOM structure. When possible, use descriptive attributes like data-testid to decouple tests from presentation. In automation, locators are often combined with waits to handle dynamic content.

Outside web automation, the term locator also appears in other domains. In GUI automation and software engineering, a locator can be a path, coordinate, or identifier that enables a program to locate a component. In networking and distributed systems, a locator can refer to a resource address or a location operator that maps a name to a physical or logical address.

Locators face challenges such as dynamic content, changing attributes, and multi-instance pages. Maintenance involves monitoring locator reliability, updating selectors after changes, and documenting locator strategies to assist future tests and automation tasks.