Checking if strings start with specific prefixes is crucial for URL validation, file type detection, protocol checking, and implementing features like autocomplete or command parsing in JavaScript applications. With over 25 years of experience in software development and as the creator of CoreUI, I’ve implemented prefix checking extensively in components like search filters, file uploads, and routing systems where determining string beginnings is essential for proper functionality. From my extensive expertise, the most modern and intuitive solution is using the ES6 startsWith() method, which provides a clear boolean result. This approach is readable, efficient, and specifically designed for prefix detection with excellent performance characteristics.