To ensure that JavaScript runs correctly across different user agents, what should you do?

• A. Test your scripts in the latest versions of popular browsers
• B. Convert scripts to a server-side language for compatibility
• C. Write separate scripts for each browser
• D. Avoid testing to save time

Answer: (A)

Cross-browser compatibility for JavaScript hinges on testing across the major user agents to uncover engine differences and feature support. Since different browsers run JavaScript with different engines and may implement DOM APIs or timing in slightly distinct ways, verifying your scripts in the latest versions of popular browsers (such as Chrome, Firefox, Safari, and Edge) helps you catch issues early and adjust code, polyfills, or fallbacks accordingly. This practice reduces runtime surprises for users on various devices and setups.

Other approaches fall short: moving code to the server won’t guarantee the same interactive behavior in the client, and writing separate scripts for each browser isn’t scalable or maintainable. Skipping tests means you’re likely to encounter errors in some environments. Emphasizing testing, along with feature detection and progressive enhancement, gives you robust, adaptable code that works across the diverse landscape of user agents.