sockjs-client is a JavaScript library that provides a WebSocket-compatible API for real-time, bidirectional communication between a web browser and a server. It functions as a transport-layer abstraction that ensures a stable full-duplex connection by emulating socket behavior.
The library is distinguished by its automatic protocol-fallback mechanisms. When native WebSockets are unavailable or blocked by restrictive network environments, such as firewalls or proxies, it switches to HTTP-streaming emulation or XHR-polling to maintain connectivity.
It covers capabilities for cross-domain data streaming and session-based connection tracking. The client interface allows for the configuration of transport options, timeout durations, and custom session identifiers to manage communication channels across different domains.