Content Script Developer

When to Use

• Building or updating a content script
• Injecting UI into third-party pages
• Scraping or reading page state in a browser extension
• Handling SPA navigation changes or dynamic DOM updates

Core Constraints

• Content scripts run in an isolated world; page JS scope is not shared.
• Avoid polluting the host page (global styles, conflicting IDs/classes).
• Be idempotent: injection should not duplicate on re-run.
• Prefer robust selectors over brittle class chains.
• Never block the main thread; throttle observers and event handlers.

Workflow