WebTransport is almost here to allow UDP-like exchange in the browser

Summary

HTTP/3 has been in progress since 2018. It is based on Google's QUIC protocol (which is itself based on UDP), and fixes several issues around the classic TCP protocol, on which HTTP and WebSockets are based. These include: Head-of-line blocking HTTP/2 allows multiplexing, so a single connection can stream multiple resources simultaneously. However, if a single resource fails, all other resources on that connection are held up until any missing packets are retransmitted. With QUIC, only the failing resource is affected. Faster performance QUIC is more performant than TCP in many ways. QUIC can handle security features by itself, rather than handing responsibility off to other protocols like TLS — meaning fewer round trips. And streams provide better transport efficiency than the older packet mechanism. That can make a significant difference, especially on high-latency networks. Better network transitions QUIC uses a unique connection ID to handle the source and destination of each request — to ensure that packets are delivered correctly. This ID can persist between different networks, meaning that, for example, a download can continue without getting interrupted if you switch from Wi-Fi to a mobile network. HTTP/2, on the other hand, uses IP addresses as identifiers, so network transitions can be problematic. Unreliable transport HTTP/3 supports unreliable data transmission via datagrams. The WebTransport API provides low-level access to two-way communication via HTTP/3, taking advantage of the above benefits, and supporting both reliable and unreliable data transmission. To open a connection to an HTTP/3 server, you pass its URL to the WebTransport() constructor. Note that the scheme needs to be HTTPS, and the port number needs to be explicitly specified. Once the WebTransport.ready promise fulfills, you can start using the connection. Also note that you can respond to the connection closing by waiting for the WebTransport.closed promise to fulfill. Errors returned ...