Cloudflare is a service that helps protect and accelerate websites. It provides a global network of data centers, which act as intermediaries between a website and its visitors. The service helps to reduce latency, improve performance, and protect against malicious attacks such as DDoS (distributed denial-of-service). Cloudflare also provides additional services such as Web Application Firewall (WAF), DNS management, and content delivery networks (CDN). For JavaScript developers, Cloudflare can be used to optimize the loading times of webpages and applications, as well as provide security and protection.