Always detect the runtime environment before using environment-specific APIs or utilities. This is crucial for networking applications that may run in browsers, Node.js servers, or cross-platform contexts. Key practices: 1. Use platform-specific utilities when available (e.g., `path.posix.join` for consistent path handling) 2. Check for environment-specific globals before accessing them (e.g., `typeof window !== 'undefined' && 'CSS' in window` before using `window.CSS.supports()`) 3. Use explicit module prefixes for built-in modules (e.g., `"node:url"` instead of `"url"` for Node.js built-ins) Example of proper environment detection: ```typescript // Check for browser environment before using browser APIs if (!this.isServer && typeof window !== 'undefined' && 'CSS' in window) { this.isViewTransitionTypesSupported = window.CSS.supports(...) } // Use Node.js module prefix for built-in modules import { fileURLToPath } from 'node:url' // Use platform-specific path utilities path.posix.join(routesDirectoryFromRoot, v.filePath as string) ``` This approach prevents runtime errors and ensures your networking code works reliably across different deployment environments.