版本：3.1.0-preview1.19508.20
- https://cdn.bootcdn.net/ajax/libs/microsoft-signalr/3.1.0-preview1.19508.20/signalr.js
- https://cdn.bootcdn.net/ajax/libs/microsoft-signalr/3.1.0-preview1.19508.20/signalr.min.js
ASP.NET Core SignalR is an open-source library that simplifies adding real-time web functionality to apps. Real-time web functionality enables server-side code to push content to clients instantly. This client can also be used with the Azure SignalR Service for enabling serverless real-time experiences.