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name: selector-strategies description: CSS/XPath selector best practices for web automation (dropdowns, dynamic tables, nested components). Use when: writing selectors, handling dynamic content, React apps, robust attributes, dynamic element handling, selector maintenance.

Selector Strategies

Best practices for CSS and XPath selectors in RPA automation.

Core Principles

1. Prefer stable attributes: data-testid, aria-label, name over classes/IDs
2. Anchor to reliable parents: Combine structural + semantic selectors
3. Avoid brittle indices: Never nth-child, :first, [1]
4. Handle dynamic content: Use text contains, partial matches, attributes
5. Document intent: Comment why selector was chosen

Robust Attributes (Priority Order)

Attribute	Stability	Notes
data-testid	★★★★★	Made for testing, never changes for styling
data-*	★★★★☆	Custom data attributes are stable
aria-label	★★★★☆	Accessibility, rarely changes
name	★★★★☆	Form inputs, usually stable
id	★★★☆☆	Can be dynamic (e.g., user-12345)
class	★★☆☆☆	Often changes with CSS refactors

Selector Hierarchies

GOOD: Anchor → Semantic → Leaf
[data-testid="login-form"] → input[name="username"]

BAD: Deep chain of classes
div.container > div.row > div.col > input.form-control

Dynamic Element Handling

Pattern	CSS	XPath
Text contains	:has-text("Submit")	//*[contains(text(),"Submit")]
Partial attr	[href*="/products"]	//*[contains(@href,"/products")]
Attr starts	[id^="user-"]	//*[starts-with(@id,"user-")]
Attr ends	[class$="-active"]	//*[ends-with(@class,"-active")]
Sibling	h2 + p	//h2/following-sibling::p[1]

Maintenance Tips

1. Group selectors by feature: Create selector constants per page/feature
2. Version selectors: Tag selectors with app version when known to break
3. Fallback selectors: Provide primary + backup for critical elements
4. Wait strategies: Combine selectors with proper wait conditions

Anti-Patterns

/* NEVER */
div:nth-child(3)           /* Brittle - breaks on DOM change */
.button:first             /* Fragile - assumes button order */
#react-root-12345         /* Dynamic ID - changes each render */
[class*="active"]         /* Too broad - matches multiple */

Examples

See examples/ folder for good/bad comparisons.

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Parent: ../_index.md